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Issues of Co-ordinate Collection Technologies for Rural Property Boundary Surveys
in Queensland
by ROBERT MATTHEW WEBB
Bachelor of Applied Science (Surveying) 1989 Diploma of Electronics 1992
A THESIS submitted in partial fulfilment of the requirements for the degree of
Master of Applied Science (Research)
Centre for Built Environment and Engineering Research Faculty of Built Environment and Engineering Queensland University of Technology
2005
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Issues of Co-ordinate Collection Technologies for Rural Cadastral Surveys in Queensland Webb, Robert Matthew Queensland University of Technology Key Words: global positioning system, GPS, cadastral surveying and mapping, traceability of measurements, measurement based spatial information systems.
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TITLE: Issues of Co-ordinate Collection Technologies for Rural Property Boundary Surveys in Queensland
Author: ROBERT MATTHEW WEBB Bachelor of Applied Science (Surveying) 1989 Diploma of Electronics 1992
A THESIS submitted in partial fulfilment of the requirements for the degree of Master of Applied Science (Research) Centre for Built Environment and Engineering Research Faculty of Built Environment and Engineering Queensland University of Technology
Advisory Committee: Principal Supervisor: Dr John Hayes Associate Supervisor: Mr Murray Harris
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Abstract of the Thesis Issues of Co-ordinate Collection Technologies for Rural Property Boundary
Surveys in Queensland
Master of Applied Science (Research) The use of co-ordinates as a description of land boundaries and their limitations has been investigated given recent advances in GPS measurement technology and its proliferation in the surveying and mapping industry. While the use of coordinate information is in essence a representation of reality at a given point in time, it is shown that they can be used within a well-defined framework for summary purposes. The conceptual and operational elements of a measurement-based spatial information system are developed in order to determine if it could aid in the organisation of land boundary information. The fundamental concepts of this information system are that measurements are the primary carriers of metric information. The investigation reveals that measurement-based concepts can serve as the foundation of a multi-purpose spatial information system. Increasing instrument precisions available to surveyors are providing quality measurements with decreasing uncertainties from standard daily operations. Much of this measurement information is in digital form and can provide useful additions of new information as and when they become available to the system. Control measurements are integrated into the system in the same manner as cadastral measurements. The addition of measurements increases the accuracy of the information system over time. The concept of a local controlled area and surface movement indicators are briefly covered relating to geo-movements of cadastral evidence. Some issues surrounding the historical foundations of geodetic datums are studied as they provides a basis of knowledge of where future spatial information developments may occur given current understandings and technological ability. A review of International and Australian measurement systems is presented. In this context, issues surrounding GPS traceability are explored as a means of demonstrating conformance with suitably recognised quantities of length and time. Discussion is held on the legal acceptance of measurements and reviews rules of evidence questioning the term geographical position used in Australian courts. An investigative study into rural property boundary surveys for subdivision purposes has been undertaken to provide comparative discussion on issues of changing methods and evolving technology approaches to the measurement challenges using GPS techniques.
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TABLE OF CONTENTS ______________________________________________________ Thesis Title……………………………………………………………………i Thesis Abstract……………………………………………………………… iv Table of Contents……………………………………………………………. v List of Figures…………………………………………………………….. viii List of Tables………………………………………………………………. x List of Abbreviations……………………………………………………… xi Declaration by the Candidate……………………………………………… xiv Acknowledgments ………………………………………………………… xv 1. INTRODUCTION
1.1 Introduction and Overview ………………………………………1 1.2 Problem Statement and Motivation …………………………...…3 1.3 Aims and Research Objective ………………………………..… 8 1.4 Thesis Contributions ……………………………………………11 1.5 Organisation of Thesis ………………………………………....12
2. BACKGROUND ASPECTS TO BOUNDARY SURVEYING
2.1 Introduction ……………………………………………………. 17 2.2 Cadastral Communication……………………………..……….. 19
2.2.1 Communication Theory………………………………. 25 2.2.2 Need for Redundancy………………………………… 28
2.3 Interpretation of Cadastral Information………………………… 31 2.3.1 Notion of Best Evidence……………………………… 33 2.3.2 Issues of Integrity…………………………………….. 38
2.4 Cadastral Survey Legislation and Measurements……………… 43 2.5 Changing Nature of Datums…………………………………… 51
2.5.1 Early Design of National Geodetic Networks……….. 53 2.6 Description and Limitations of Coordinate Based Positions…… 60 2.7 Issues of Spatial Information Systems…………………………. 64 2.8 Summary…………………………………………………………68
3. CONCEPTS OF MEASUREMENT-BASED SPATIAL INFORMATION SYSTEM FOR A FUTURE QUEENSLAND CADASTRE
3.1 Introduction ……………………………………………………. 69 3.2 Definitions of Measurement Based Systems …………………… 71 3.2.1 Context of a "System" …………………………………71
3.2.2 Management Control and Performance……………….. 74 3.2.3 Measures of System Improvements…………………… 79
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3.3 Concept of a Measurement Based Cadastral System…………… 84 3.3.1 Notions of a Measurement Based Spatial Information
System………………………………………………….. 86 3.3.2 Measurements are First Class Objects ………………… 87
3.3.3 Storage of Measurements ……………………………… 88 3.3.4 Processing of Measurements ………………………….. 91 3.3.5 Local Adjustment of Measurements …………………… 93 3.3.6 Maintenance Updates of Measurement Databases ……. 95 3.3.7 Storage of Co-ordinates for Efficiency Reasons …….. 96
3.3.8 Gradual Data Collection……………………………….. 97 3.3.9 Increase in Spatial Accuracy over Time………………..100 3.3.10 Change in Co-ordinate and Derived Metric Values... 102 3.3.11 Data Quality Assessment……………………………. 103
3.3.12 Differentiation between Legal and Non-Legal Metric Values……………………………………….. 105
3.3.13 Digitised Photogrammetric Co-ordinates and Ambulatory Boundaries…...………………………… 106
3.4 MBSIS Information Integration…………………………………. 109 3.5 Summary …………………………………………………………118
4. SURVEY CONTROL FRAMEWORKS AND INFRASTRUCTURE
4.1 Introduction ………………………………………………………120 4.2 Geodetic Positioning…………………………………………….. 122 4.3 National Geodetic Framework…………………………………... 126 4.3.1 International Compatibilities………………………….. 131 4.4 Datums - Static or Dynamic? …………………………………... 133
4.4.1 Limits of Model Precision…………………………….. 143 4.5 Indicators of Surface Movements……………………………….. 149 4.6 Concept of Local Controlled Areas (LCA)……………………….154 4.7 Summary………………………………………………………….165 5. GPS MEASUREMENT TECHNOLOGY ISSUES
5.1 Introduction……………………………………………………..167 5.2 Australian and International Framework relating to Measurement ………………………………………………...169
5.2.1 International Measurement System ……………….….171 5.2.2 Australian Framework Relating to Measurement ……174 5.3 Calibration and Traceability discussion associated with
GPS derived Measurements ………………..179 5.4 Timing Issues associated with
GPS Instrumentation ………………………188
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5.5 Legal Acceptance of Measurements………………………….....196 5.5.1 Rules of Evidence …………………………………….197
5.5.2 Notion of a Presumption of Accuracy ……….……….199 5.5.3 Appeal of Evidence relating to Geographical Position..202
5.5.4 Discussion ...…………………………………………..207 5.6 Summary ...……………………………………………………...209
6. CONCLUSIONS AND FUTURE DIRECTIONS 6.1 Conclusions and Recommendations …………………….…… 211 6.2 Open questions for future research…………..…………………216
Appendix A INVESTIGATIVE STUDY: RURAL CADASTRAL SUBDIVISION BY GPS TECHNIQUES
A.1 Introduction …………………………………………………….218 A.2 Rural Subdivision by Geodetic GPS Project Overview ………219
A.3 GPS Measurement Approach …………………………………. 222 A.4 Discussion on Method Analysis ………………………………. 224 A.5 Comparison of Approaches – Then and Now….……………… 231 A.6 Summary..……………………………………………………… 237
BIBLIOGRAPHY…………………………………………………………239 LEGAL CASES CITED ………………………………………………….266
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LIST OF FIGURES ___________________________________________________ Figure 1.1 Concept map of this thesis……………………………………13
Figure 2.1 Shannon Weaver model of a general communication system..25 Figure 2.2 More sophisticated model of the communication process
applied to interpersonal communication………………… 26 Figure 2.3 National Geodetic Surveys 1945..…………………………… 54 Figure 2.4 Geodetic Control Surveys 1975.………………………….….. 55 Figure 2.5 Geodetic Control Surveys in Qld 1975 ……………………… 56 Figure 2.6 100km Geodetic Infrastructure Network over Queensland 1999 .………… 59 Figure 3.1 Processing of boundary measurements ………………………. 87 Figure 3.2 Entity-Relationship schema of linkages between elements……89 Figure 3.3 Graphic representation of cadastral error ellipses after adjustment, sample Linthorpe Valley DCDB…….. 99 Figure 3.4 Enlargement demonstration of cadastral corners requiring
corrective re-measurement action………………………. 100 Figure 3.5 Sample graph of performance indicator: improvement in relative accuracy in rural boundary locations for a district … 101 Figure 3.6 Graphical accuracy of parcel boundaries …………………...105 Figure 3.7 Cadastral data cycle for both current and proposed scheme…………………………………………..114 Figure 3.8 Conceptual relationship between survey measurements and co-ordinates …………………………………………. 116 Figure 4.1 Sample geometry of rural cadastral survey using traditional total station techniques ………………………..124 Figure 4.2 Sample geometry of rural survey using modern RTK-GPS techniques ……………………………………..125 Figure 4.3 Townsville ARGN Coordinate Time Series Graph January 1998 to March 2002 ……………………………………….146 Figure 4.4 The author undertaking geodetic control survey – Karangi Dam, NSW ………………………………………………. 147 Figure 4.5 Australian Regional Earthquake Hazard Map ………………....149 Figure 4.6 Queensland Earthquake map indicating events larger than Richter magnitude 2.0 ……………………………………..151 Figure 4.7 Hierarchy of models in geodetic deformation analysis ……......157 Figure 4.8 Optimised Monitoring Network B based on 13 LCA ……….… 162 Figure 4.9 Model of 200km usability zones from 13 monitoring sites …… 163
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Figure 5.1 Australia’s hierarchy of physical units and standards…………..176 Figure 5.2 The author undertaking geodetic GPS measurements for length comparison purposes at Coombabah EDM baseline range....183 Figure 5.3 A potential model developed by Boey (1999) of traceability of GPST measurements ……………………….……………192 Figure 5.4 Direct spatial connection to the Zero-order AFN….………… …194 Figure A.1 The author undertaking a cadastral connection experiment to nearby geodetic control ……………………………….......219 Figure A.2 Cunnamulla rural survey study area …………………………... 220 Figure A.3 Extract of Geodata Raster 250K Topographic Map over the Cunnamulla project study area………….…………221 Figure A.4 Cunnamulla pre-subdivision and proposed boundary geometry..224 Figure A.5 Diagram of non-recommended single-radiation GPS Method.....225 Figure A.6 Sample R.P. from Blackall project noting the comments of measurement technique…………………………………….. 228
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LIST OF TABLES _______________________________________________________________
Table 2.1 Differences between Aboriginal land tenure systems and the Australian cadastral system…………………….. 21
Table 2.2 Cook’s (2003) matrix of communication methods and effects on organisation……………………………………………24
Table 2.3 Effects of deterioration and loss of integrity of survey monuments….……………………………………..39
Table 2.4 Boey’s (1999) summary of survey legislation and complementary publications in Australia..………………..44
Table 2.5 Boey’s (1999) summary of survey statutory requirements by jurisdictions……………………………………………….46
Table 2.6 Boey’s (1999) summary of accuracy standards in Australian States………………………………………….48 Table 2.7 Boey’s (1999) summary of calibration and standardisation
requirements in Australia…………………………………50
Table 3.1 Cook’s (1993) accountability regimes for cadastral control and cadastral surveying………………………………………. 82 Table 3.2 Levels of Maturity for Cadastral Representations in Qld.……113
Table 4.1 Hierarchy of Internationally recognised reference systems applicable to Australia…………………………..……….132
Table 4.2 Derived summary details for selected continuous GPS monitoring stations in Australia………………………….145
Table 4.3 LCA Placement within hierarchical reference frameworks..….159
Table 5.1 Recommended performance and assessment summary
functions for testing static GPS survey networks……….182
Table 5.2 Summary of time and frequency links used to establish traceability to UTC………………………………………189
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LIST OF ABBREVIATIONS _____________________________________________________
AFN Australian Fiducial Network
AGCC Australian Global Navigation Satellite System Coordination Committee
AGD66 Australian Geodetic Datum 1966
AGD84 Australian Geodetic Datum 1984
AGSO Australian Geological Survey Organisation
AHD Australian Height Datum at 1971
ALS Airborne Laser Scanning
ANN Australian National Network
ANS Australian National Spheroid
AMG66 Australian Map Grid 1966
AMG84 Australian Map Grid 1984
AMIS Asset Management Information System
ARGN Australian Regional GPS Network
ASDI Australian Spatial Data Infrastructure
AUSLIG Australian Surveying and Land Information Group
BBS Computer Bulletin Board Service
BIML International Bureau of Legal Metrology (Bureau International de Metrologie
Legale, BIML)
BIPM Bureau International des Poids et Mesures (BIPM)
BS Integrity Monitoring Network Base System (Base Station)
C/A code Clear Access Code or Coarse Acquisition Code
CCTF Consultative Committee for Time and Frequency (BIPM)
CORS Continuously Operating Reference Station
CPD Continuing Professional Development
CRS Celestial Reference System
CRTP Commercial Receiver Test Program
DCDB Digital Cadastral Data Base
DNR Department of Natural Resources Qld Australia
DoD Department of Defence (U.S.)
DOP Dilution of Precision
DORIS Doppler Orbitography and Radio positioning Integrated by Satellite
DOTARS Commonwealth Department of Transport and Regional Services
EDM Electronic Distance Measurement
FIG International Federation of Surveyors
FGCS Federal Geodetic Control Subcommittee (USA)
FSV Fast Static Vector
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GDA94 Geocentric Datum of Australia at 1994
GDOP Geometric Dilution of Precision
GIS Geographic Information System
GLONASS Global Orbiting Navigation Satellite System
GNSS Global Navigation Satellite System
GP General Practitioner (medical)
GPS Global Positioning System
GRS80 Geodetic Reference system 1980
IAG International Astronomical Union
IAU International Astronomical Union
ICAO International Civil Aviation Authority
ICRF International Celestial Reference Frame
ICRS International Celestial Reference System
ICSM Intergovernmental Committee on Surveying and Mapping
ICSU International Council for Science Union
IERS International Earth Rotation Service
IGS International GPS for Geodynamics Service
ILAC International Laboratory Accreditation Cooperation
IPS Ionospheric Prediction Service
ISO International Standards Organisation
ITRF International Terrestrial Reference Frame
ITRS International Terrestrial Reference System
IUGG International Union of Geodesy and Geophysics
LCA Local Controlled Area
LIS Land Information System
LLR Lunar Laser Ranging
LOTS Land Ownership & Tenure System (South Australia)
LRIS Land Registration & Information Services (Canada)
LWG Legal Working Group of AGCC
MBLIS Measurement Based Land Information System
MBSIS Measurement Based Spatial Information System
Met Meteorological Observation
MGA94 Map Grid of Australia 1994
MRA Mutual Recognition Arrangement derived from BIPM
MSL Mean Sea Level
NAVSTAR Navigation Satellite Timing and Ranging
NATA National Association of Testing Authorities, Australia
NBS National Bureau of Standards (USA)
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NIMA National Image Mapping Agency (formally US Department of
Mapping (DMA))
NMI National Metrology Institutes
NML CSIRO National Measurement Laboratory
NR&M Queensland Department of Natural Resources & Mines.
NZGD49 New Zealand Geodetic Datum 1949
OIML International Organisation for Legal Metrology
OTF On The Fly (GPS ambiguity resolution)
P code Precision or Private Code for GPS
PDOP Position Dilution of Precision
PPM Parts Per Million
QA Quality Assurance
QLIC Qld Land Information Council
QSIIC Qld Spatial Information Infrastructure Council
RINEX Receiver Independent Exchange Format
RMS Root Mean Squared
RTK Real Time Kinematic
SCIGN Southern California Integrated GPS Network
SCDB Survey Control Data Base (NR&M Queensland)
SDI Spatial Data Infrastructure
SI International System of Units (Systeme International)
SIS Spatial Information System
SLR Satellite Laser Ranging
SNR Signal to Noise Ratio
SP1 Standards and Specifications for Control Surveys, Special Pub. No. 1
TQM Total Quality Management
TSB Territorial Sea Baseline
UHF Ultra High Frequency (radio communication)
UN United Nations
UNCLOS United Nations Convention on Law Of the Sea
US DoD United States Department of Defence
UTC Universal Time Coordinated.
VCV Variance-CoVariance
VHF Very High Frequency (radio communication)
VLBI Very Long Baseline Interferometry
VRS Virtual Reference System
WAAS Wide Area Augmentation System
WGS84 World Geodetic System 1984
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DECLARATION BY THE CANDIDATE _____________________________________________________________ Statement of Original Authorship
The work contained in this thesis has not been previously submitted for a
degree or diploma at any other higher education institution. To the best
of my knowledge and belief, the thesis contains no material previously
published or written by another person except where due reference is
made.
Signed: ………………………
Date: ………………………
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ACKNOWLEDGEMENTS ____________________________________________________ Writing a thesis is an intense, solitary endeavour. Many people and
organisations have contributed to its creation and production for which I am
very grateful to all of them. A few of them, however, deserve to be specially
mentioned.
I would like to express my deep appreciation to my principal research adviser
Dr. John Cook for his overall guidance, encouragement, patience, reflective
feedback and support throughout my years of study. I must also extend my
gratitude to other thesis supervisors who have assisted in guiding this research.
In chronological order these include the following QUT academic staff:
Associate Professor Brian Hannigan, Dr John Cook, Dr Susan Buzer, Dr John
Hayes and Mr Murray Harris for the many hours spent discussing various
directions, reviews, options and concepts contained herein.
This thesis has taken various pathways of discovery during its production. Life-
changing events and mobility issues have impacted upon the timely conclusion
of its production. In addition, I would like to thank the persons of the School of
Planning, Landscape Architecture and Surveying (now part of the School of
Urban Development), Faculty of Built Environment and Engineering for their
guidance, patience and assistance throughout my time at Queensland University
of Technology.
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Chapter One: Introduction
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CHAPTER ONE
INTRODUCTION
However, if not all explorers were surveyors, it is true to say that surveyors were almost invariably explorers. The nature of the task which confronted the surveyor in the new colony demanded a willingness to explore
and survey new territory.1
1.1 Introduction and Overview This thesis investigates Global Positioning System (GPS) measurement
technology as a means of describing rural property point positioning and
boundaries. These boundary description methods will lead to improved integrity
of the rural cadastre in a Queensland land administration environment.
A challenge concerning the surveying profession during the last decade has been
whether coordinate descriptions derived from geodetic GPS measurements can
provide reliable and accurate information for property survey purposes.
Chapter One: Introduction
2
The major broad aim of this research project is to investigate the following
hypothesis:
GPS co-ordinate survey control methods can provide
efficient rural cadastral surveys suitably recognised by
authorities and improve the integrity of spatially
related rural boundaries.
Many professional disciplines are coming to the realisation that spatial
information is best represented and communicated in a "map-based" form on a
common datum allowing integration of a wide selection of data themes. The
assembly and integration of this spatial information requires a network of
appropriately distributed control points of known horizontal and/or vertical
locations usually described by co-ordinate values in relation to a reference
framework.
Cadastral mapping has traditionally relied upon well-established cadastral survey
techniques of traversing and radiation. The equipment used to accomplish these
surveys has evolved since the 1970s from optical theodolites and steel bands, to
total stations and data recorder technology. With recent advances in satellite
technologies, space-based positioning systems are now becoming capable of
replacing conventional survey methods for many applications, especially when
striving for consistent sub-centimetre three-dimensional positioning.
Survey measurements undertaken in the real-world environment begin to lose
their integrity from the time of observation due to the movement of marks and
the ground that holds them. This integrity degradation results from movement of
the monumentation marks and the ground itself which holds these marks. The
practical surveying world is a dynamic environment consisting of various
1 McCarthy, J., 1988, Mapmakers of Australia:The History of the Australian Institute of Cartographers, published by Australian Institute of Cartographers. Page 2.
Chapter One: Introduction
3
elements and influences of growth and decay. Dynamic cadastral systems
attempt to describe this dynamic ground conditions environment. Current
positioning knowledge often relies upon effective sampling of this environment
at a discrete point in time to provide a model of the dynamic situation. Therefore,
spatial information collected by surveyors for geodetic, cadastral or as-
constructed purposes requires consideration of the temporal aspects to model the
dynamic ground conditions environment.
Many organisations, including local authorities, are investing in management
information approaches using Geographical Information Systems (GIS)
technology. These GIS approaches arguably should contain a reliable geodetic
and cadastral representation of the real-world environment as foundation
information. This foundation information is often organised in a territorial
information hierarchy and provides a solid basis from which other spatial
information is related. Sound management of such spatial information is
demonstrably realised through hierarchical information structures and system
approaches.2 For many statistical and comparison applications, information is
best organised in a territorial manner. Territorial information aggregation allows
meaningful comparisons to be made between individual and collective districts.
The effective use of survey-derived co-ordinate information in hierarchical
structures for territorial structured information systems will ultimately rely on
structured, layer-based surveyed data incorporating time-series information.
1.2 Problem Statement and Motivation
Surveyors are the principal professionals responsible for describing positions
related to property and asset descriptions within a recognised framework. In
undertaking this process of description, surveyors can benefit from applied
technology approaches in the fundamental operation of their business. More
2 Rajabifard, A., Escobar, F., and Williamson, I.P., 2000. ‘Hierarchical Spatial Reasoning Applied to Spatial Data Infrastructures,’ Proceedings of National Conference, Sydney, Mapping Science Institute Australia, December 2000. Available on-line Internet http://www.geom.unimelb.edu.au/research/publications/IPW/4_00Rajab_MS.pdf (June 2002)
Chapter One: Introduction
4
recently, people involved in GIS are increasingly using coordinate information
for position description purposes.
Land surveying professionals can make important contributions to economic
development, environmental management, social stability, land administration
and land management. This is characterised by published documents from
cadastral studies and investigations, such as those of Kaufman & Stendler FIG
Commission 7, 1998;3 Williamson, 1998;4 Hannigan & Webb, 1996;5 F.I.G.
1995;6 Cook, 1994;7 and others.
In Queensland, traditional cadastral approaches have matured through various
reform processes to attain a reasonable reputation for well-defined processes and
well-recognised guarantees of security for private land ownership to the
community at large. The Cadastre is the primary means of providing information about property rights. More specifically, the Cadastre provides the private and public sector with:
1. information identifying those people who have interests in parcels of land;
2. information about those interests (e.g. nature and duration of rights, restrictions, and responsibilities);
3. information about the parcels (e.g. their location, size, improvements, value).8
In essence, cadastral systems link descriptions of people and interests to a land
parcel.
This thesis is concerned, in part, with new GPS technology approaches for
collection and analysis of spatial information describing the land parcel. It also
investigates measurement information communicated by a language of co-
ordinates or other relative positional representations (vectors).
3 Kaufmann, J and Stendler, D,1998, Cadastre 2014: A Vision for a Future Cadastral System. FIG Commission 7, 1998. Available online Internet http://www.swisstopo.ch/fig-wg71/cad2014/cad2014/index.htm (May 2001) 4 Williamson, I.P.,1998, ‘Cadastral Reform and the Future of the Surveying Professional’, Proceeding of 39th Australian Surveyors Congress. Tasmania, Australian Institute of Surveyors, November 1998, p305-322 5 Hannigan, BJ and Webb, RM., 1996, ‘Rearrangement of Property Boundaries to Facilitate Optimum Rural Land Use.’ Proceedings of 37th Australian Surveyors Congress. Perth, Australian Institute of Surveyors, April 1996, p479-495. 6 FIG, 1995, Statement on the Cadastre. International Federation of Surveyors, FIG publication No. 11. Available on-line Internet http://www.fig7.org.uk/publications/cadastre/statement_on_cadastre.html (accessed Aug.2000) 7 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis - Queensland University of Technology. 8 FIG, 1995, Statement on the Cadastre. International Federation of Surveyors, FIG publication No. 11. Section 1.1 Available on-line Internet http://www.fig7.org.uk/publications/cadastre/statement_on_cadastre.html (accessed Aug.2000)
Chapter One: Introduction
5
The International Federation of Surveyors (F.I.G.) vision for Cadastre 2014
highlights some particular points relevant to this thesis study. One aim of cadastral reform projects is to improve services of the cadastral systems. The automation of cadastral systems is widely seen as an appropriate tool to improve the performance of cadastral systems. Automation, however, of the traditional perfectible systems without re-engineering the procedures aspects may result in performance failure. The innovation of cadastral systems tend to be in the direction that cadastral systems will be embedded in land infrastructure systems. ..... Cadastral 2014 will be a complete documentation of public and private rights and restrictions for land owners and land users. It will be embedded in a broader land information system, fully coordinated and automated in that section of land registration and cadastral mapping.9
The ‘innovation of cadastral systems’ component fundamentally describes the
way cadastres are measured, organised and administered in recognition of
computerised information systems. Kaufmann and Steindler’s vision statements
make earlier reference to the United Nations (UN) Interregional Meeting of
Experts on the Cadastre, Bogor Declaration of 1996. They build upon the earlier
UN outputs and forecast what cadastral systems fundamentally should achieve
by 2014.10
These documents provide a vision statement for cadastral systems but with
straight-forward common elements such as:
• Be simple and effective • Be adaptable to rates and patterns of populations • Provide access to land, security of tenure and trading of land
rights • Provide a vast array of options • Include all state and private lands • Be part of a national spatial infrastructure.11
These elements provide the foundation to land administration mechanisms in a
hierarchical land management approach. The overall notions of Cadastre 2014
depict one of complete land area coverage, following modern information and
systems theory approaches with a straight-forward information structure. The
workshop findings and recommendations resulting from The Bathurst
9 Ibid., p.10 10FIG, 1996,United Nations Interregional Meeting of Experts on the Cadastre: Bogor Declaration. UN-FIG Bogor Declaration on Cadastral Reform, Available on-line Internet http://sunspot.sli.unimelb.edu.au/fig7/Bogor/BogorDeclaration. (accessed Oct.2000) 11 Kaufmann, J and Stendler, D., 1998, Cadastre 2014: A Vision for a Future Cadastral System. FIG Commission 7, 1998 p.43. Available online Internet http://www.swisstopo.ch/fig-wg71/cad2014/cad2014/index.htm (May 2001)
Chapter One: Introduction
6
Declaration on Land Administration for Sustainable Development support this
land management approach.12
This dissertation also considers these foundation elements as part of proposing
an improved communication, recording and interpretation approach. The
examination of issues and concepts within this thesis complement the aims of
statutory and government authorities undertaking cadastral reform projects.
Arguably, the words from the Cadastre 2014 statement of most importance and
influence to the challenges and motivation for this thesis undertaking are that the
developed researched concepts: … will be embedded in a broader land information system, fully coordinated and automated in that section of land registration and cadastral mapping.13
An additional motivating factor for this investigative work has been to further
develop and refine issues associated with undertaking GPS measurement
approaches for applications of rural property surveys and GIS data collection.
This aspect has evolved and developed from the author’s previous undertakings
in projects:
• Research towards a land boundary re-arrangement scheme - a
European concept called remembrement, and its potential for
implementation in rural agricultural regions of Queensland;14
• Base data collection, translation and construction of several
pilot GIS projects relating to the remembrement concept
applied on local catchment regions on the Darling Downs;15
12 FIG, 1999, The Bathurst Declaration on Land Administration for Sustainable Development. FIG Publication No. 21. Published by The International Federation of Surveyors (FIG), December 1999, Frederiksberg, Denmark. Available on-line Internet http://www.ddl.org/figtree/pub/figpub/pub21/figpub21.htm#RECOMMENDATIONS (accessed Oct.2001) 13 Kaufmann, J and Stendler, D., 1998, Cadastre 2014: A Vision for a Future Cadastral System. FIG Commission 7, 1998 p.10. Available online Internet http://www.swisstopo.ch/fig-wg71/cad2014/cad2014/index.htm (May 2001) 14 Hannigan B.J, 1992, Re-arrangement of Cadastral Boundaries to Facilitate Optimum Rural Land Use, December 1992. 96 pp. Published by School of Surveying, QUT. Final report of research project funded by The Surveyors Board of Queensland, Brisbane. 15 Hannigan B.J., and Webb R.M, 1993,L.I.S. Technology and the Process of Rural Reconstruction, December, 142 pages. Research project sponsored by The Australian Key Centre in Land Information Studies and The Queensland University of Technology.
Chapter One: Introduction
7
• Utilisation of photogrammetric techniques, GPS and geodetic
technologies for field data collection and re-measurement
functions;16
• Communication of rural farm scenarios for boundary re-
arrangements through GIS analysis and map-based
communication for future land management.17
This motivation is further supported by casual observations of large-scale land
development projects in the South-Western Brisbane corridor, where
transformation of land-use continues from tracts of mostly rural lands to the
creation of new master-planned residential communities. It is common that one
land development company progressively brings new land stocks to the
marketplace achieving these residential communities. This typically occurs over
a period of time in the order of perhaps one to two decades. Archer described
this characteristic in 1977, thus: ….. the large-scale land development or new town approach to urban development is one in which a single organisation, private or government, owns or controls a large area of land near the metropolis with the objective of developing it as a new town or urban settlement. The area should be upwards of say 400 hectares and preferably in new town size parcels. The landowner organisation plans the land use pattern and carries out the land development for this area, markets the project as a new town to attract land users, investors and building developers to the estate, then sells the serviced sites for private, government building development, and manages the urban development of its land as a whole.18
This characteristic change involves increasing levels of complexity in the land
development process. More efficient information processes can help to cope with
this increasing complexity. This thesis proposes at chapter 3 an improved
approach to deal with electronic measurement information, particularly spatial
information derived from GPS technology, to support this land development
process with more efficient information processes based on a measurement
centric idea.
16 Poster paper prepared as a by-product of this thesis work to communicate alternative approaches to rural property boundary surveys. Presented to Research Concentration in Design and Construction Studies, School of Planning, Landscape Architecture and Surveying, QUT, 1999. 17 Webb R.M.,1996, 'Mapping for Future Land Management: Mapping for a Proposed Land Boundary Re-Arrangement in a Rural Queensland Catchment', Proceedings of Mapping Sciences'96 -Mapping for Management, Canberra National Convention Centre, p397-419. 18 Archer, R.W., 1977, ‘The Theory and Practice of Large-Scale Land Development’, Royal Australian Planning Institute Journal, Vol.15 No.2, May, pp.67-72.
Chapter One: Introduction
8
1.3 Aims and Research Objective
An emphasis of this research undertaking has been to investigate the possibilities
and potential that new GPS technology approaches can contribute towards rural
property surveys. This research undertaking is largely conceptual in nature based
on extensive literature reviews and critical discussion with key advisors on
future directions of approaches to rural cadastral surveys within the broader
spatial information industry. This research aims to uphold community
expectations relating to adequate description of the location of property rights
and interests. This sufficiency of description context notes the importance that
society places on land specifically in terms of assurance of the security of land
title.
Arguably, government authorities and organisations dealing with spatial
information require an automated multi-purpose cadastre to facilitate informed
decision-making. One strategy of multi-purpose cadastres is to create and
perpetuate the understandings of resource use including the perpetuation of
human understanding of cadastral boundaries through land developments.
Management decisions concerning government functions such as land and
environment management, land administration including cadastral infrastructure
can be realised through a common spatial information framework. During the
late 1990s, the Queensland Spatial Information Infrastructure Council (QSIIC),
formerly the Queensland Land Information Council (QLIC) identified
foundation spatial information components described in the Qld Spatial
Information Infrastructure Strategy.19
19 Queensland Land Information Council , 2000, Queensland Spatial Information Infrastructure Strategy – Data Frameworks, Available on-line Internet http://www.qsiis.qld.gov.au/cgi-bin/php/menu.phtml?menu=Data+Framework (accessed June 2002)
Chapter One: Introduction
9
This strategy was developed to provide easy access to relevant and reliable
integrated spatial information for Queensland.20 Identified foundation spatial
information components with the highest priority included the geodetic network
and cadastral boundaries with descriptions. This thesis contributes to both of
these spatial information components.
Some ideas within this thesis have built upon previous research work undertaken
by Dr John Cook relating to issues in the design of viable cadastral survey and
mapping organisation. Cook (1994) briefly discussed the concept of Local
Controlled Areas (LCA) as elements of a district or subdistrict within a larger
framework for management purposes broadly. Of special significance to
surveyors is the management of updating digital land boundary geo-information
within a LCA.21
Cook (1994) additionally summarised the noteworthy point that land boundary
data in an updateable and agreeable electronic format would allow the following:
• practically alleviate the need to update cadastral working maps by manual methods;
• allow issue of cadastral mapping with up-to-the-minute accuracy and completeness;
• provide objective management information as a consequence of successive adjustments to indicate progression or regression in surveying data quality in each Local Controlled Area.22
A focus of the author’s research combines Cook’s third point and the common
workplace notion that surveyors jettison almost all raw surveying data to
produce an analogue, paper-based, graphically encoded communication product.
This somewhat antiquated information processing approach has led the author to
propose a more efficient information approach in the form of a measurement-
based spatial information system (MBSIS). This MBSIS concept would operate
20 Queensland Land Information Council , 2000, Queensland Spatial Information Infrastructure Strategy – Data Frameworks, Available on-line Internet http://www.qsiis.qld.gov.au/cgi-bin/php/menu.phtml?menu=Data+Framework (accessed June 2002) 21 Cook, J.S.,1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology, p.131. 22 Ibid., p.10
Chapter One: Introduction
10
within a local controlled area for building a localised multipurpose cadastre that
aligns with many of the visions outlined in Cadastre 2014. A research objective
has been the exploration and development of the concept of a measurement-
based spatial information system (MBSIS) contained in chapter 3. This objective
related research adds to the testing in providing efficient rural cadastral surveys
suitably recognised by authorities.
This dissertation also aims to investigate establishing a structured approach to
implementing reliable and up-to-date land parcel descriptions in a local area.
Additional outcomes would include exploration of technical issues arising from
survey methods using GPS techniques. This is of particular relevance not only in
Australia but also in developing nations that lack both geodetic survey
infrastructure and efficient land administration functions.
A related research objective is the testing of the statement that measurements are
suitable recognised by authorities. This is challenged in chapter five with
exploration of the contentious issue of legal traceability facing the spatial
information industry, review of literature, rules of evidence, and legal precedent
of geographic position. In addition, a research objective to learn from historically
past applications of performing rural cadastral survey by GPS methods is
contained in Appendix A. A detailed comparison of techniques is undertaken in
light of current industry best practice and geoid models.
Chapter One: Introduction
11
1.4 Thesis Contributions
GPS techniques and applications directly relating to cadastral survey operations
and applications are in their infancy in Australia. Arguments supporting this
claim are contained in various studies by Boey & Hill 1995; 23 Boey & Parker
1996; 24 McDaid, Denys and Hoogsteden 1997; 25 Talbot, Boey and Gerdan1997;
26 and Higgins 1999.27
These studies acknowledge the real potential that GPS techniques can offer to
specifically improving the time and positional efficiencies in undertaking
property boundary measurements. Several studies have examined the
measurement process and drawn conclusions about the practical levels of
efficiency. Conclusions from these studies indicate some decrease in labour costs
while not compromising on accuracy standards.
The literature review and summation process has gathered many issues relating
to the technical achievements of new space-derived measurements and national
and international reference frameworks. This thesis explores opportunities for
developing new multi-purpose cadastre in light of recent knowledge and
understandings of regional geodynamics.
The increased use of GPS technologies within the surveying industry requires
the establishment of consistent standards of best practice, calibration and legal
traceability as well as consideration of geodesy fundamental and cadastral
surveying concepts. From this perspective, this dissertation makes a contribution
to spatial information industry.
23 Boey, S.S., and Hill, C.D.,1995, ‘Can GPS measurements be legally used for cadastral surveying?’, The Australian Surveyor, Vol. 40(2)1995 p.101-111 24 Boey, S.S., and Parker, J.R., 1996, ‘A review of current Australian survey legislation in the face of modern measuring technology’, The Australian Surveyor, Vol. 41(4) 1996 p.278-287 25 McDaid, D., Denys, P., and Hoogsteden, C., 1997, ‘Cadastral Surveys and the GPS Option: origin, definition, time and cost comparisons for an Urban Cadastral Survey’, TransTasman Surveyor.Vol.1 No.2, July 1997 p45-52 26 Talbot, N., Boey,S., and Gerdan, G., 1997, ‘Verification methods for establishing legally traceable GPS measurements in Australia’, Proceedings of 38th Australian Surveyors Congress, Newcastle, April 1997 p.17.1-17.11. 27 Higgins, M.B., 1999, ‘Positioning and Measurement into the 21st Century’, Keynote Address Proceedings of 40th Australian Surveyors Congress, Fremantle, November 1999 p.15-24.
Chapter One: Introduction
12
1.5 Organisation of Thesis
This thesis contains a number of major areas of investigation and reviews that
address and challenge the major broad research aim. These major areas include:
• Background Aspects;
• Measurement Based Information System;
• Geodetic Frameworks;
• Measurement Technology Issues;
• Investigative study considering GPS measurement approaches to rural property subdivision in the Queensland context.
Figure 1.1 maps out the flow of ideas and organisation of this thesis. It contains
key words associated with each chapter in a logical order.
Chapter Two, Background Aspects, discusses some fundamentals of
communication theory applied to the cadastral process. This discussion places in
context the process of a cadastral measurement description through the action of
encoding and later decoding of survey information. It also raises issues of
information entropy and the need for redundancy in the communication process.
Further, this section summarises aspects of property boundary evidence prior to
the investigation of central concepts detailed in later chapters. This section
discusses the provocative issue of coordinate based descriptions and limitations
in the context of suitable measurement representations.
Chapter One: Introduction
13
Figure 1.1: Concept map of this thesis
Chapter One: Introduction
14
Chapter Two also reviews the prescription of measurement accuracy by state
authorities with application to property boundary surveys. This provides
background impressions of the varying accuracy descriptions and provides some
basis for adopting position-based property information. This chapter also
provides a brief historical background to datum changes and highlights some
early understandings of geodetic modelling within the Australian region. This
chapter is relevant to the major aim of this research because it demonstrates the
linkage of cadastral communication over time periods that aid the integrity of
rural boundaries.
Chapter Three explores foundation concepts and ideas relating to a
measurement-based spatial information system (MBSIS) approach. The MBSIS
exploration focuses towards Queensland’s cadastral fabric underpinned by
essential geodetic infrastructure. This section discusses the management of
spatial information within a hierarchical structure. This notion of a measurement
centric approach applied to cadastral purposes explores issues of performance
metrics in the context of improved management. This management approach
contains discussion and investigation of the various sub-notions to some level of
detail to support an implementation phase. The concept has merit given the
inherent value contained in survey observation information in an updateable
electronic format. Spatial information management goals, as described by QSIIC
(2000), could be arguably achieved using the proposed MBSIS approach.28
Chapter Three also provides discussion on issues of information integration
between current co-ordinate based systems and measurement-based systems
within a decentralized organization environment. This discussion involves some
level of sophistication of digital cadastral databases given the current knowledge
28 Queensland Land Information Council, 2000, Queensland Spatial Information Infrastructure Strategy(QSIIC) – Data Frameworks, Available on-line Internet http://www.qsiis.qld.gov.au/ cgi-
n/php/menu.phtml?menu=Data+Framework (accessed June 2002)
Chapter One: Introduction
15
of survey accurate cadastral representations. Storage of GPS measurements (in
the form of four-dimensional vectors) in an MBSIS for cadastral representations
directly relate to the research hypothesis.
Chapter Four, Geodetic Frameworks, discusses the importance underpinning
survey control frameworks and its infrastructure links towards spatial
information systems. These survey control frameworks require the description of
inherent features in such a manner that they adequately contain associated time-
series attributes. A foreword to a national geodetic framework within a holistic
positioning hierarchy discusses the expressed meaning behind geodetic
positioning. Arguments are additionally explored relating to an ideal of a
dynamic datum in the context of a geodetic framework representing the real-
world. This viewpoint is supported by evidence relating earth dynamics and
seismic activity in Queensland. Recent but limited time-series results from the
Australian Regional GPS Network (ARGN) partially support this argument.
Some suggested geodetic infrastructure networks over Queensland land and
marine interests are presented that may be of assistance to Local Controlled
Areas operating within a MBSIS.
Chapter Five, Measurement Technology Issues, investigates issues of
measurement technology influencing the surveyor’s role in providing reliable
and consistent descriptions. Many arguments contained in this chapter directly
support the testing of the research hypothesis. Issues explored include those
pertaining to both measurement calibration and traceability. Additional
discussion relates to fundamental timing issues associated with these
measurement approaches that indirectly contribute to the major research aim.
Nationally compiled best practice guidelines generally guide measurement
approaches utilised by surveyors. These best practice guidelines change and
adapt with time considering impacts of new measurement technology. The
topical issue of legal acceptance of measurements is briefly explored with a
Chapter One: Introduction
16
study of notable measurement instruments (not necessarily used by surveyors)
and the legal recognition afforded to these instruments. The issue under focus
relates to a Supreme Court decision appealing the validity of the geographic
position of a fishing vessel determined partially by a satellite navigation device.
Chapter Six, Conclusions, provides a summary of the research undertakings and
highlights the major findings. It includes recommendations for future research
directions and identifies several open questions relating to this research
undertaking.
Appendix A contributes an investigative study focusing on a rural cadastral
subdivision conducted by GPS measurement methods over a decade ago. A
discussion of the GPS measurement methods is included to highlight the benefits
of hindsight and the evolving nature of technology applications in this field.
Hindsight is significant in this case due to the limited knowledge and modelling
of the dynamic earth a decade ago. Linkage to measurement-based information
systems in this study confirms that the surveying industry's best practice
guidelines for undertaking GPS surveys are maturing as new technical solutions
evolve. Given the relevant nature of the investigative study to the research
hypothesis, issues arising from chapter five, GPS measurement technology, are
further discussed at a technical level given current surveying approaches.
Chapter Two: Background Aspects to Boundary Surveying
17
CHAPTER TWO
BACKGROUND ASPECTS
TO BOUNDARY SURVEYING
The profession of Surveying is as old as civilisation itself; as a necessary criterion for
civilisation is the erection of an administrative procedure for dealing with property, especially, as in early agrarian civilisations, land. Even in
our own Australian history the role of the Surveyor is inextricably bound up with land
administration.29
2.1 Introduction
With the implementation of the Geocentric Datum of Australia (GDA), it is
evident that co-ordinates of survey points cannot be held fixed for all time but
require refinement and updating from time to time. With improved measuring
technology becoming available and increasing densification of control survey
29 Glasscock, J.T.C., 1974, ‘Education for Surveyors’, The Australian Surveyor, vol.26, no.1.
Chapter Two: Background Aspects to Boundary Surveying
18
networks, Lambert’s (1981) following comments are perhaps of great relevance
as the surveying community enter the new millennium. For some time now, surveyors have been faced with the dilemma that equipment and techniques are continually being evolved with capacities for ever increasing accuracy and which in their use are introducing conflict with previously accepted permanent survey data. This conflict appears over the complete range of cadastral, topographic, engineering and geodetic surveys. Additionally, surveyors have been provided with computers which permit the ready adjustment, coordination and storage of large quantities of survey data. Unfortunately, an obsession for holding previous coordinates unchanged often leads the surveyor to use these computers for the purpose of distorting his modern, extremely accurate measurements into compatibility with older and less accurate work. 30
These 1980s ideas as outlined by Lambert are still relevant today in the
consideration of applying technology to geodetic, engineering and cadastral
projects.
This chapter provides background information for concepts and ideas contained
in later chapters. This chapter firstly discusses communication theory and its
essential links to cadastral surveying and mapping. Interpretation of cadastral
evidence follows to provide consistency and the notion of best evidence used for
cadastral reinstatement purposes. This section then presents cadastral survey
legislation and the prescribed measurement accuracy in the context of the
changing nature of geodetic datums. A discussion develops concerning
limitations and opportunities of coordinate based positions for description
purposes in light of recent implementations of spatial information systems
technology applied to large spatial datasets.
The significant of cadastral communication to the hypothesis is that the
importance of integrity of descriptions relating to property boundaries are not
diminished by the use of a coordinated based measurement approach such as
GPS. Whilst GPS is used for geodetic control purposes, the idea of its direct use
to assist in providing description of a boundary location is explored in the
context of cadastral communication issues.
30 Lambert, B.P. ,1981, ‘Australian geodetic coordinates - keeping up with the times’, The Australian Surveyor, Vol.30 No.8, December 1981 p.491.
Chapter Two: Background Aspects to Boundary Surveying
19
2.2 Cadastral Communication
Land administration systems attempt to describe or model human understandings
of land resources. Many cadastral systems are in a state of reform as they try to
adapt and cope with new challenges. Land policy directions and management
goals often drive these systems. Clear management goals and performance
indicators can achieve measurable success in these land administration systems.
In the context of cadastral reform and providing improved solutions, Kaufmann
(2002) contributes the following comments in the context of why benchmarking
of cadastral systems is useful to community and government. With a worldwide perspective, the situation in the field of cadastre is rather heterogeneous. Next to perfectly functioning systems, we find incomplete and partial systems. In countries with colonial backgrounds, cadastres often cover only the colonized land not taking the still existing traditional and customary rights into consideration. Other countries – mainly those in transition – have to build up cadastral systems from scratch, and in other countries, the cadastral systems have been destroyed due to conflicts and have to be re-established. Cadastral systems, where they exist, usually have a long tradition, and in most cases have existed for more than a century. Over this long period of time, the systems have been improved and perfected. The emphasis on perfection may have created a certain heaviness, and often the performance has not kept up with the customer’s needs. Nowadays, in the era of globalization, decisions concerning land resource matters have to be taken much faster than in earlier times. The worldwide interest in Cadastre 2014 has shown, that traditional systems often increasingly do not correspond to such new requirements. Where partial cadastral systems exist, they have to be completed to cover the whole territory. Only when complete and all-encompassing can they serve society in a beneficial way. In these cases, it must also be discussed at the same time, if the contents of the systems are sufficient to provide the needed services. Where customary and traditional rights exist in parallel, these must be taken into consideration. When cadastral systems are to be newly introduced, there is a need to design a completely new solution to provide the appropriate services over a long period of time. Where a re-establishment of the cadastral system is necessary, the question often arises whether it is appropriate to have the earlier situation restored. In all the aforementioned cases, the changes caused by technological development, especially IT, are to be considered. All these activities are different forms of cadastral reforms. When undertaking reform it makes sense to search for the best solution. Benchmarking can help to identify best practices and to find the best solution for a given problem.31
31 Kaufmann J., 2002, ‘Benchmarking Cadastral Systems – Results of the Working Group 7.1 of FIG-Commission 7’, Proceedings of FIG Commission 7 publication Benchmarking Cadastral Systems. Compiled and edited by Daniel Steudler and Jurg Kaufmann, pp.14-15, April 2002.
Chapter Two: Background Aspects to Boundary Surveying
20
In essence, the process of cadastral benchmarking based on objective, uniform
information maintained over a period of time can provide a means of comparing,
identifying weaknesses and achieving improved performance in land
management. Nevertheless, does this process assist with improved cadastral
communication?
Communication of interests in land, property rights or restrictions and extents of
a land parcel can be expressed in oral and written forms. Oral forms of this land
communication relate to the native title approach in identifying the natural
features of the land parcel. Written forms of this communication are the modern
approach to cadastral land administration. The survey plan is essentially the
formalised written communiqué of boundary understandings at the time of
survey.
Both of these communication forms rely upon at least one of the following
memory functions for describing the interests or extents in land over periods of
time:
• human memory
• libraries and paper records
• computer memory – storage.
These are elementary functions of storing the initial information and recalling
the same information later.
The importance of land within aboriginal culture transcends generations and
involves a spiritual and material connection to the land, where land is not
measurable in mathematical terms. Rather, traditional interests in land are
quantified through the traditions and customs as held by the aboriginal people.32
A review of the methods in determining native land claims shows a common
alignment that natural topographic features of the landscape describe boundaries,
more or less. A fundamental difference between aboriginal land tenure and the
32 Brazenor, C., Ogleby, C. and Williamson, I., 1999, ‘The Spatial Dimension of Aboriginal Land Tenure’, Proceedings of 6th South East Asian Surveyors Congress, Freemantle Australia. p.162.
Chapter Two: Background Aspects to Boundary Surveying
21
Australian cadastral system is the concepts of ownership and the role of land in
society.
Aboriginal land ownership has generally been described as one of communal or
tribal in nature. Driven by spiritual beliefs, the aboriginal notion of custodianship
is maintaining the land for future generations. Applications for native title
recognition under Australian law must provide proof that the group has
maintained a connection to that country being claimed, generally from the time
of colonisation.33
The Brazenor, Ogleby and Williamson (1999) study provides comparisons
between the aboriginal and western-society land administration systems. Aboriginal people consider land to be integral importance for determining cultural identity, where land is present in all aspects of life. The western view of land is one that it can be owned exclusive of others, viewed as a commodity which may be bought, sold, leased, inherited or use for the storage and safe keeping of wealth for economic gains. 34
ABORIGINAL LAND TENURE AUSTRALIAN CADASTRAL
SYSTEM
Evidence of land tenure through song, dance,
ceremony, paintings and oral traditions
Torrens system of registration of interests in
land, Cadastre displays the spatial context of
interests in land
Spiritual and physical connection to land Land as a commodity
Ownership/ Custodians of land, in a communal
manner
Individual grants from the crown , exclusive
ownership of land
Boundaries: Topographic features Boundaries : Mathematically defined, use of
monumentation for demarcation
Transfer of land through inheritance Transfer of land through sale, lease and
inheritance
Rights in neighbouring land, overlapping
rights, restrictions and responsibilities
Rights in neighbouring land are restricted
through State and local regulations
33Commonwealth of Australia, 2001, Gathering Information for your Native Title Application, National Native Title Tribunal, Fact sheet No. 5G, August 2001. Available on-line Internet http://www.nntt.gov.au/publications/1021887568_19798.html (accessed Feb.2003) 34 Brazenor, C., Ogleby, C. and Williamson, I., 1999, ‘The Spatial Dimension of Aboriginal Land Tenure’, Proceedings of 6th South East Asian Surveyors Congress, Freemantle Australia. p.164.
Chapter Two: Background Aspects to Boundary Surveying
22
Table 2.1: Differences between Aboriginal land tenure systems and the Australian cadastral system.35
The comparison table above clearly demonstrates a very different approach to
boundaries and the descriptions of land. An important function performed by
modern cadastral surveyors is to mark boundaries and describe lands to allow
particular property transactions to proceed. The language of surveying involves
various symbolisms for communicating an understanding about the identity of
land parcels. This symbolism includes:
• Marks placed on the ground that communicate information to any person who can recognise the marks and what they mean;
• Written descriptions of land parcels contained in plans of survey and showing the symbols and conventions understood at the time the plan was prepared;
• Additional records of survey in the form of reports, calculations and the like.36
A purpose of cadastral systems is to communicate an understanding of the rights
and obligations of people in relation to real property over extensive time periods.
However, breakdowns in communication and understanding can occur over these
time periods in relation to the symbolism used and marks on the ground. Cook
(2003) summarises the technical level of the entropy situation relating to
surveying symbolism, thus – In the absence of adequate systems maintenance, marks on the ground can be lost or deteriorate to become unrecognisable. Similarly, paper records can disintegrate and inks can fade to a point where documents can become unreadable. Electronic data is often susceptible to fading and corruption through magnetic field interference and other causes. Thus, maintaining the meanings and understandings related to boundaries depends firstly on maintaining the marks and symbolism on which those understandings are based.37
To place these issues relating to boundaries in context, the land development
process in Queensland for existing freehold tenure generally involves several
common outcome processes involving land administration updating functions.
These being in chronological order:
• Proposal by land developer initiated;
35 Based on original table contained in Ibid., p.164. 36 J.S. Cook, 2003, PSB620 Law for Surveyors, Teaching Resources, Lecture 2 – Cadastral Problems Conceptualised as Breakdowns in Communication Processes. School of Design and Built Environment, QUT. Accessed on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/surveying-law/boundaries/02-communication.htm (accessed April 2003) 37 Ibid.
Chapter Two: Background Aspects to Boundary Surveying
23
• Preliminary approval stage normally undertaken by local government
authority;
• Final approval stage normally undertaken by local government authority;
and
• Registration of titling stage to a central collection normally undertaken
by state government authority.
After the parcel-based action has preceded through these processes, an updating
function usually follows:
• updating of title information to individual parcels, and
• updating to cadastral descriptions, addresses and others details of interest
to the local authority.
These land development processes rely upon clear communication of land
related issues and the actions involved within cadastral administration functions.
Therefore, the process of benchmarking cadastral systems as a function of a
project life-cycle serves a useful purpose in examining the following points:
• The factors leading to improvements in communication.
• Factors leading to a breakdown in cadastral communication – notion of
cadastral entropy – Shannon’s (1948) example of relative entropy
relating to redundancy associated with ordinary English language is
about 50%. This means that when we write English half of what we write
is determined by the structure of the language and half is chosen freely.38
• Improved descriptions – work by the sender, for example, uniform plan
presentation requirements.
• Improved interpretation – work by the receiver, for example, rules of
evidence and interpretation, following legal precedents.
• Improved methods and practices in avoiding ambiguity, for example,
standards and protocols.
Chapter Two: Background Aspects to Boundary Surveying
24
Arguably, Cook (1994) has contributed useful groundwork investigations in the
land administration area of communication and has examined common
communication methods and their relationship to the organization of land
understandings.
Table 2.2: Cook’s (2003) matrix of communication methods and effects on organisations.39
Perhaps it would be better if cadastral systems and cadastral reform projects
acknowledge the importance of communication theory and organisational
structures relating to spatial information. The International Federation of
Surveyors (FIG) has acknowledged this important point with the recent focus of
FIG Commission 7 working group investigating global standards in cadastre.
This group has recently made an official approach to the International Standards
Organisation (ISO) technical commission to adopt the FIG Commission 7
‘Statement on the Cadastre’, (1995) as an ISO standard noting that a definition
of global legal standards will be difficult or even impossible.40
38 Shannon, C.E., 1948, ‘A Mathematical Theory of Communication’, The Bell System Technical Journal, Vol. 27, pp.379-423, 623-656, July, October, 1948. Copy available on-line Internet http://cm.bell-labs.com/cm/ms/what/shannonday/shannon1948.pdf Example page 14.(accessed December 2002) 39 J.S. Cook, 2003, PSB620 Law for Surveyors, Teaching Resources, Lecture 2 – Cadastral Problems Conceptualised as Breakdowns in Communication Processes. School of Design and Built Environment, QUT. Accessed on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/surveying-law/boundaries/02-communication.htm (accessed April 2003) 40 Hawerk, I.W., 2001, ‘Standards in Cadastre – Sense or Nonsense?’, Proceedings of FIG Commission 7 Annual Meeting, June 2001. Gavle, Sweden. Available on-line Internet http://www.fig.net/figtree/standards_network/hawerk_2001.pdf (accessed Dec. 2002)
Chapter Two: Background Aspects to Boundary Surveying
25
2.2.1 Communication Theory
Cadastral processes in Australia have similarities to fundamental communication
theory and processes. The simplest model of the communication process is as
follows:
SENDER → MESSAGE → RECEIVER
This simple model indicates three essential elements of communication.
However, if one of the elements is missing, no communication can occur. For
example, we can send a message to someone, but if it is not heard or understood
by that person, no communication has occurred.
Figure 2.1: Shannon-Weaver model of a general communication system.41 Developing a virtually error-free surveying and mapping communication relies upon a satisfactory degree of redundancy in all communication processes.
Data collected and assembled for describing, knowledge transfer or to aid in
information for decision-making purposes. Data that constitutes this information
requires encoding ready for later transmission. A surveying example of the
encoding process is the assembly of spatial information from field measurement
data for production of a survey plan.
Of additional interest is the Greenway paper: Greenway I, 2002, ‘Standards and Surveyors: FIG's Past and Future Response.’ Proceedings of FIG XXII Congress, Washington, DC, 19-26 April 2002. Available on-line Internet http://www.fig.net/figtree/standards_network/greenway_fig2002.pdf (accessed Dec. 2002)
Chapter Two: Background Aspects to Boundary Surveying
26
This encoding of information may contain noise leading to the deterioration or
conflicts associated with some parts of the information. A surveying example of
this noise factor in a survey plan may be the accidental text annotation of reverse
bearing description attached to a rectangular boundary while the diagram of the
boundary conflicts with the bearing description.
This example creates a potentially ambiguous situation of what describes the
real-world situation. The need for redundancy in this communication example
assists to reinforce the correct and intended situation. However, survey-plan
presentation guidelines have established a consistent manner in which to assign
certain meanings towards the intended description of a spatial relationship. The
use of standards and protocols assists in avoiding ambiguity. This improved
description is work undertaken by the sender of the message in the
communication process.
Figure 2.2: More sophisticated model of the communication process applied to interpersonal communication.42
The transmission of information is commonly associated with the use of a
telephone or radio broadcast. However, for survey information, the transmission 41 Shannon, C.E., 1948, ‘A Mathematical Theory of Communication’, The Bell System Technical Journal, Vol. 27, pp.379-423, 623-656, July, October, 1948. Copy available on-line Internet http://cm.bell-labs.com/cm/ms/what/shannonday/shannon1948.pdf Diagram page 2.(accessed December 2002) 42 Stoner J., Collins R., and Yetton P., 1985, Management in Australia, page 600, published by Prentice-Hall of Australia.
Chapter Two: Background Aspects to Boundary Surveying
27
component is the safe and secure storage of the encoded information for
transmission of the memory function over time. This transmission of encoded
survey information, held in appropriate paper or film records, is possible through
library collections or repository organisations.
Government land administrations have recently introduced the use of computer
memory for storage and subsequent transmission purposes. This computer
storage creates key improved conditions in aspects such as physical space, rapid
access to stored electronic information, and allows relative ease in duplication of
electronic records for other purposes or complete collection duplication in
another location for safety purposes.
How does noise affect information? Information is, we must steadily remember, a measure of one’s freedom of choice in selecting a message. The greater this freedom of choice, and hence the greater the information, the greater is the uncertainty that the message actually selected is some particular one. Thus greater freedom of choice, greater uncertainty, greater information go hand in hand.43
Potential for noise into the transmission of survey information is evident in the
analogue form of paper or microfilm records being damaged or deteriorating
over extended periods of time. Similarly, electronic viruses or other potentially
damaging activities could affect digital computer records creating a noise
situation requiring additional interpretation of the contained information.
Data required for use after the transmission process requires a decoding process
to extract meaning from the transmission. The receiver of the transmitted
information generally undertakes this decoding. A survey example of the
decoding process involves notions of best cadastral evidence and guides to
interpretation of the records. A successful decoding process is characterised by
clarity of interpretation and avoids null information or ambiguous situations 43 W. Weaver and C. E. Shannon, The Mathematical Theory of Communication, Urbana, Illinois: University of Illinois Press, 1949, republished in paperback 1963. Prefaced by Warren Weaver's introduction, ``Recent contributions to the mathematical theory of communication,'' the paper was included in The Mathematical Theory of Communication, published by the University of Illinois Press in 1949. Brief Excepts from Introduction to: Claude Shannon’s The Mathematical Theory of Communication, are available online Internet http://darkwing.uoregon.edu/~felsing/virtual_asia/info.html (accessed Dec 2002)
Chapter Two: Background Aspects to Boundary Surveying
28
associated with the decoded information. This assumes correct encoding of the
piece of information at the commencement of the communication process.
Additionally, redundant information can confirm a single piece of information,
adding strength to its correct transmission, while conflicting information creates
ambiguous situations leading to a breakdown in confidence associated with the
information and communication process.
2.2.2 Need for Redundancy
Surveying procedures usually incorporate redundancy as part of normal
communication processes because it is found to be efficient in practice. This
point requires detailed consideration in any proposal to modify evidentiary
provisions relating to boundaries, geometric descriptions and the use of
coordinates.
Improving measurement technology has led to improved and automated
technical aspects of redundancy associated with the measurement process. Elfick
et.al., (1994) explains the fundamentals of errors in measurements as follows: It can be unconditionally stated that
1. no measurement is exact 2. every measurement contains errors 3. the true value of a measurement is never known and therefore 4. the exact error present is always unknown.
These facts are demonstrated by the following: When a distance is scaled with a rule divided into centimetres, the distances can be read only to a millimetre (by interpolation). If a better rule graduated in millimetres is available, however, the same distance might be estimated to tenths of a millimetre. Obviously, accuracy of measurements depends on the division size, reliability of equipment used and human limitations in interpolating closer than about one-tenth of a scale division. As better equipment is developed, measurement will more closely approach their true values.44
Measurement redundancy has become an important issue in making comparisons
of new measurement technologies. As an example of this, a surveyor may
undertake a traditional topographic survey with a total station and retro-reflector
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prism for a well-defined surface feature. The surveyor may take a dual face
observation for angular measurement and a small number (say five) of slope
distance EDM measurements to determine the relative position of the object
measured. The surveyor could undertake the same topographic survey with a
real- time-kinematic (RTK) technique and acquire 180 automated epochs
(observation data) to produce the same spatial information with real-time
statistical measures and much more redundant information.45 This example
requires qualification that redundancy is desirable not only at the measurement
stage but also in the recording of that measurement information and electronic
transfers of that information to another device for later processing.
Cook (2001) provides further notable comments to the issue of redundant
information: Redundancy – implying more than minimal information – introduces two possibilities. One is that redundant information may become corroborative and mutually reinforcing. The second is that redundant information may be contradictory and lead to uncertainty about what to believe. Thus, redundancy is essential to the very idea of ‘error’. Suspecting that an error exists implies some acceptance of a result deemed more likely and rejection of a result deemed less likely to truly represent a state of affairs. Most statistical routines involve redundant information and possibility of reducing errors.46
Entropy can be understood as the opposite of redundancy when applied
to information theory.47 Natural entropy in surveying relates to gradually
breakdown and disorder of survey marks, documentation and
monumentation. Indeed, the evidence placed by the surveyor in
conjunction with a survey action has a limited-life caused by various
influences. This aspect is detailed in table 2.3. It is this understanding of
losses through entropy influences that forms the basis for a risk
management strategy and in identifying opportunities to improve
integrity in cadastral systems.
44 Elfick M., Fryer J., Brinker R., Wolf P., 1994, Elementary Surveying, Page 17. 9th Edition, Harper Collins Publishers, USA. 45 See figure 4.1 and figure 4.2 for a graphic comparison of survey approaches undertaken in Linthorpe Valley. 46 Cook, J.S., 2001, Personal Communication– Communication Theory and Surveying Practice, work in progress. School of Design and Built Environment, QUT. 47 Underwood, Mike 2002, Redundancy and Entropy, contained in Communication, Cultural & Media Studies Resources CCMS database. Available on-line Internet http://www.cultsock.ndirect.co.uk/MUHome/cshtml/index.html (Accessed Dec. 2002)
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However limitations are an inherit nature of coordinates. A single number has no
redundancy and allows no way of checking whether an error has occurred in its
reading or transcribing. Much material has been written in recent times about the use of coordinates as evidence of boundary location. Coordinates are numbers and have insufficient redundancy to know that transmission of a message is free of significant errors. The effect of an error can vary from something trivial to something disastrous. The fate of Air New Zealand aircraft that crashed into Mount Erebus in Antarctica on 28 November 1979 is testimony to disastrous consequences arising from undue reliance on coordinates.48
In essence, recognition of redundancy aspects dominating over entropy
influences relate to the heart of the reinstatement challenge. Arguably, boundary
corners communicated in the sole form of coordinate information on a document
of title should not be assigned conclusive evidence status to the exclusion of
other evidence.
Coordinate information has many inherent variables and is a representative
quantity that a mistake in communication of a single digit is likely with written
communication methods (for example, a transcription error). A mistake of a
single digit as part of a coordinate description alone can have serious
ramifications in a safety-of-life situation. A coordinate description without
suitable redundancy qualities should not be regarded as conclusive evidence of a
boundary corner without qualification of the knowledge of methods, techniques
and relativities of the determination.
48 Cook, J.S., 2003, PSB620 Law for Surveyors, Teaching Resources, Lecture 3 – Entropy and Breakdown in Surveying and Mapping Information. School of Design and Built Environment, QUT. Accessed on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/surveying-law/boundaries/03-Entropy.htm (accessed April 2003) Aviation Safety Network, variable date, Accident Investigations Reports and Database, Air New Zealand -Mount Erebus accident – Findings of (NZ) Royal Commission of Inquiry was that a change or misunderstanding had occurred in the longitude coordinate of a waypoint. The aircrew apparently relied solely on coordinate information for position in the circumstances of a complete sector white-out due to cloud cover. Further details can be found at http://aviation-safety.net/database/1979/791128-0.htm (accessed May 2003)
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2.3 Interpretation of Cadastral Information The Collins Dictionary and Thesaurus defines the term re-instatement as:
‘to restore to a former rank or condition’;49
While the Oxford Dictionary defines the term as: -
‘to restore, replace in lost position, etc’.50
When this term is used in relation to the cadastre it has strong suggestions of re-
locating on the ground any boundary positions which may have become lost,
confused or in dispute.
Most of the Queensland cadastral framework had been set in place by the turn of
the previous century (1900). Each parcel of land had a unique, unambiguous
description via a system of hierarchical descriptions including State, County,
Parish and Portion. It is the surveyor who records the parcel dimensions as
measured between marks (in various forms), as well as calculations of area and
other relevant descriptions.51 The current parcel description approach used in
Queensland is the lot number on plan number to identify uniquely a land parcel.
Some principle issues of early reinstatement approaches that required surveyors’
consideration revolve around:
• The measurements of both direction and distance would have been poor
by today’s measurement standards. For example comparing pre-1900
measurements with post- year 2000 best-practice standards and electronic
instrumentation techniques;
• Monumentation and marking on the ground techniques had a limited life
because of disturbance or decay;52
49 Collins, 1987, Dictionary and Thesaurus in One Volume, Collins Publishers, London p840. 50 Oxford, 1995, The Oxford Dictionary and Thesaurus, edited by Sara Tulloch. Published by Oxford University Press. 51 Detailed information and diagrams on historical survey marks is contained in Smith, I.K., 1996,’ The Search for Evidence – Rural Cadastral Boundaries: Following in the footsteps of the original Surveyor’. Proceedings of Seminar'96, Re-Instatement: Principles and Practice, Association of Consulting Surveyors, Queensland, Brisbane. 52 See table 2.3.
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• The problem of the existing cadastral design and its conflict with the
natural landscape structure or dominant pattern;53
• Australian government pursuit of closer settlement policy lead to
cadastral boundaries marked out based on a prescribed property area
regardless of the natural landscape patterns or what may be economically
sustainable for the ideal farming unit;54
• The characteristic that in some rural areas, a long time interval occurs
between re-surveys (often a few decades but as shown by the cadastral
search data and studies in Linthorpe Valley, this re-visit time period was
some 80 plus years); 55
• Some form of occupation (fencing), which in itself would have a cycle of
decay and renewal, would replace the linear aspect of boundaries in most
instances. This is particularly relevant in rural cattle and sheep land use
areas but in recent broad-acre agricultural practices, fencing is
minimised.
Interpretation of cadastral information that avoids contradiction and information
leading to uncertainty about what to believe (not mutually reinforcing) relates to
issues of the notion of best evidence and issues of integrity within cadastral
infrastructures.
53 Issues and geometric problems identified from study Hannigan B.J. and Farmer R., 1995, Rearrangement of Farm Boundaries to Facilitate Beneficial Adjustment in Primary Industries, Final report of research project QUT-2A funded by Rural Industries Research and Development Corporation pp.162. Published by School of Planning, Landscape Architecture and Surveying, Qld University of Technology, Brisbane. 54 Hannigan B.J. and Webb R.M., 1995, Rearrangement of Property Boundaries to Facilitate Optimal Rural Land Use, Final report of research project UQT-1 funded by Land and Water Resources Research and Development Corporation (LWRRDC R&D Project UQT-1) pp 9. Published by School of Planning, Landscape Architecture and Surveying, Qld University of Technology, Brisbane. 55The authors’ involvement in education of QUT surveying students in the Linthorpe Valley cadastral project area - Pittsworth district, Darling Downs region, as published in Webb R.M., 1996, 'Mapping for Future Land Management: Mapping for a Proposed Land Boundary Re-Arrangement in a Rural Queensland Catchment.' Proceedings of Mapping Sciences'96 -Mapping for Management, Mapping Science Institute of Australia, Canberra National Convention Centre. pp.397-419.
Chapter Two: Background Aspects to Boundary Surveying
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2.3.1 Notion of Best Evidence
The cadastral surveyor in Queensland follows a re-instatement process guided by
the so-called rule of best evidence. This best evidence notion has its origins in
two Queensland cases with comments made by Justice Griffith in Overland v
Lenehan and the Donaldson v Hemmant cases.56 These cases introduced and
utilised American rules as an authority in their respective decisions.57 Both cases
cite the 4th edition of Taylor on evidence. The following extract from Overland v
Lenehan (1901) demonstrates this point. In my opinion the question to be determined is what was western boundary of subdivision 10 as understood by the persons concerned at the time when the mortgage of subdivision 1B and the transfer of subdivision 10 were executed. In the case of Donaldson v. Hemmant (ante p. 85 ) I quoted from Taylor on Evidence (4th Ed., p. 1029) some rules which, I think, should be applied in construing instruments relating to land for the purpose of determining the identity of the subject matter. They may be summed up by saying that most weight should be given to those points on which the parties at the time were least likely to be mistaken. 58
The aim of these policies is to determine the intention of the parties in
establishing the boundaries expressed in the form of written documents. The
principles are that most weight should be assigned to points that the respective
parties are least likely to be mistaken about.
Justice Richmonds’ comments relate to convincing evidence of boundary
location along with describing the situation of occupation as evidence of
boundary location. He provides expert opinion to the surveying industry on this
issue and draws out the notion of long-standing occupation by citing the leading
case of Equitable Building and Investment C. v Ross. Surveying was roughly done in the early days, and has left, it seems, but few monuments, and those of the rudest. In such circumstances, there can really be no better identification of the land to which a grant relates than long and unchallenged occupation by the grantee and those who claim through him of an allotment which in position, dimensions and area corresponds, in general, though it be somewhat roughly, with the description in the grant. Neither the words of a deed, nor the lines and figures of a plan, can absolutely speak for themselves. They must in some way or other, be applied to the ground. Where
56 Supreme Court of Queensland, 1901, Donaldson v Hemmant, The Queensland Law Journal, Volume 11, p.35-44 57Brown Allan, 1980, Law Relating to Land Boundaries and Surveying. Association of Consulting Surveyors Queensland, p.154. 58 Supreme Court of Queensland, 1901, Overland v Lenehan, The Queensland Law Journal, Volume 11, p.59 –67. Griffith was Chief Justice in 1901 at the time of the Supreme Court of Queensland.
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there are no natural boundaries, the original survey-marks are gone, and there is no great difference in admeasurement, a long occupation originally authorised by the proper public authority, and acquiesced in throughout the period by the surrounding owners, is evidence of a convincing nature that the land so occupied is that which the deed conveys. Even where monuments exist which enable a more accurate survey to be made, no trifling discrepancy can be allowed to over-rule the practical interpretation put upon the instrument by such an occupation. The occupier is not to be driven to rely on a mere possessory title; but has a right to assert that the land he holds is the very land granted. Land surveying is a practical art ; which is as much as to say that it is not capable of the ideal precision of the mathematics. The most accomplished surveyors must differ in their measurements, though it may be only by some minute fraction of a link. 59
Cook’s (1996) comments reinforce the issue that principles of boundary
reinstatement are mostly a product of the legal system with the fundamental task
of surveyors to provide land parcel descriptions with a consistent and orderly
approach between monuments and measurements. Cook (1996) provides
comment on the notion of best evidence: - As a general statement of public policy, the classical statement of the law of evidence is as follows:
The judges and sages of the law have laid it down that there is but one general rule of evidence, the best that the nature of the case will allow.60
A narrow view of this general rule is that secondary evidence is admissible where primary evidence is available. As an example, the hearsay rule would generally exclude secondhand information if it were available first hand. Similarly, an original document is preferred to a copy of the document.
Appeal courts in Queensland and New Zealand have referred to Taylor on evidence, 4th. edn. In Clayton v Morrison and Donaldson v Hemmant. According to Richmond J. in Equitable Building and Investment C. v Ross, Taylor on evidence, an English Text, is an abridgement of Greenleaf on evidence, an American text. Other Queensland and New Zealand courts have followed these decisions. In summary, Greenleaf on evidence represents the law as it relates to boundaries in Queensland. Moreover, Equitable Building and Investment C. v Ross may be considered influential in terms of the weight to be accorded to occupation as evidence of boundary location. The guiding principle in trying to elucidate the intention of the parties is to give most weight to those things about which the people concerned were least likely to be mistaken. As a corollary, it follows that least weight should be given to those things about which the people concerned could easily be mistaken.
Some commentators have tried to reduce the process of weighing evidence to simplistic notions of ‘hierarchy of evidence’ and ‘monuments before measurements.’ This occurs despite Brown’s clear warning that any element
59 Supreme Court of New Zealand, 1886, Equitable Building and Investment C. v Ross, 1886, Volume 5 – New Zealand Law Review (Supreme Court), p.229-238. Page 229 provides 3 summary paragraphs of the case relating to Lambton Quay. In the absence of natural boundaries, original survey marks, no great difference in re-measurement and a long-standing occupation by adjoining owners. This extract is from page 232. 60 Omychund v. Barke 1 Atk 21 at 49;26 ER 15 at 33 per Lord Hardwicke, cited in D.Byrne and J.D.Heydon, Cross on evidence, 4th Australian edition. Sydney: Butterworths, 1991. p.78 para. 1465. Cited in Cook, 1996.
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may be accorded particular weight, depending on the circumstances.61 Analysing each element in terms of what is best should not detract from the general aim of obtaining the best evidence when seen in its totality. 62
Clearly, the important point of consideration is the best evidence that presents
itself when viewed in a holistic manner. As the reinstatement process and
approach has matured in Australia, a number of different types of evidence have
been categorised and their respective importance relative to other pieces of
evidence can be assigned weight based on which is least likely to be ambiguous.
The notion of extrinsic evidence is raised by Justice Griffith in Overland v
Lenehan.(1901) Before dealing with the facts of the case it is necessary, I think, in order to dispel a mistaken notion which seems to be the foundation of much of the argument addressed to the Court in this case, to point out that a certificate of title does not rest upon a pinnacle by itself, but is an ordinary written instrument, and that, although its operation is far-reaching, and in some respects exceptional, it must be construed in accordance with the ordinary rules for the construction of documents of title. Without extrinsic evidence to identify its subject matter it has no intelligible meaning. Extrinsic evidence is, therefore, admissible, and must be admitted, and, when admitted, must be applied in precisely the same way as in the case of any other document of title. The doctrine expressed in the words falsa demonstratio non nocet is just as applicable to it as to any other instrument of title.63
Cook (1998) provides a more recent and clear distinction between evidence of an
extrinsic and conclusive nature. Extrinsic evidence. A document of title links a person (or persons) with particular rights and obligations to a particular parcel of land. The document of title usually refers to a plan of survey and the plan of survey refers in turn to facts on the ground. Facts about people (such as a change of name) or facts on the ground may change over time. Unless the document of title can link satisfactorily to facts on the ground, the title has no intelligible meaning. As a matter of public policy, it may be possible to legislate that a document of title is conclusive evidence of certain particular. However, trying to give absolute guarantees regarding boundary evidence is imprudent.
61 Brown Allan, 1980, Law Relating to Land Boundaries and Surveying. Association of Consulting Surveyors Queensland, pp15 & 155. Cited in Cook 1996. 62 Cook J.S., 1996, 'Key Legal Principles in Boundary Reinstatement', Proceedings of Seminar'96- Re-Instatement: Principles and Practice, page 3-9. Association of Consulting Surveyors, Queensland. 63 falsa demonstratio non nocet --Descriptions usually contain redundant elements. In the event that one or more elements is inconsistent or out of line with other elements of a description, to reject as little information as possible to regain consistency is common sense. one or more elemts [sic] do not . This practice is even more appropriate when there is a sensible explanation for the inconsistency, as in the comment by the Chief Justice - 'But the northern frontage was represented as being still 7½ chains in length, without making allowance for the resumption of the strip of 37½ links from the eastern side.' Cited in Cook J.S., 1998, PSB317 Land Administration 3 teaching notes. Explanatory notes to CASE -- Overland v Lenehan (1901) 11 QLJ 59. http://www.dbe.bee.qut.edu.au/people/cookjs/psb317/ (accessed Feb. 2002)
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Conclusive evidence. An important principle in the Torrens System is to declare the certificate of title as conclusive evidence, with only a few exceptions. Other terms such as paramount and indefeasible express much the same idea. 64
In certain situations, conflicting evidence may be apparent and in absence of a
clear solution, it is normal practice for the cadastral surveyor to develop a
weighting strategy.65 It is important to obtain a complete search of
documentation including survey plans before commencing the field survey.66
Brown (1980) first presented the following hierarchy of evidence. Of noteworthy
importance is the qualifying statement made at point 10 when surveyors consider
applying a reinstatement strategy based on weight of the evidence found.
If the plan is a statement of measurements actually marked on the ground then the markings become monuments, and evidence as to their nature and position is admissible. However, the intention of the parties to the deed is of paramount importance, and the courts have laid down rules establishing the relative importance of various, sometimes conflicting, "calls" of the documents on which the surveyor must base his survey, in order to arrive at what the intention was. 1. The greatest weight must always be given to lines actually marked on the
ground. 2. Next most important are natural monuments mentioned in the deed. 3. Adjoiners - "a well established line of adjacent survey" – often rank
as natural monuments. 4. Artificial monuments rank next. 5. Maps or plans actually referred to in deed rank after artificial monuments. 6. Unmarked lines which are well recognised rank next to maps and plans of importance. 7. Bearings and distances will over-ride other calls only, in most cases, where there is no
trustworthy evidence of such other calls. 8. As between bearing and distance, neither is given overall preference - if they are
inconsistent with each other the circumstances dictate which is preferred. 9. Area (referred to by Skelton and Brown as "quantity") will in general be the least valued
evidence, but many in some cases by the key to the problem. 10. Finally, but most important of all, any one of these rules may be of more (or less) weight
in one case than another. The rules set out are for cases of conflict, they are general rules, to be used as a guide but not as a straightjacket.
The great importance of occupation is not due to any sanctity given by possession, nor to a kind of title by prescription, as stated by some writers, for example W.M. Alexander in one of his excellent papers, but to the fact that it is
64 Extrinsic evidence description Cited in J.S. Cook 1998, PSB317 Land Administration 3 Teaching Resources- Explanatory notes. http://www.dbe.bee.qut.edu.au/people/cookjs/psb317/ (accessed Feb. 2002) Conclusive evidence description Cited in Cook 1998, PSB317 Land Administration 3 Teaching Resources- Explanatory notes. http://www.dbe.bee.qut.edu.au/people/cookjs/psb317/ (accessed Feb. 2002) 65 McClelland, P., 1996, ‘The Reinstatement Process – Case Studies’, Proceedings of Seminar'96- Re-Instatement: Principles and Practice. Association of Consulting Surveyors, Queensland. Page 5 makes reference to developing a reinstatement strategy and the importance of undertaking a thorough search to obtain all available documentation prior to commencing field survey. 66 Sneddon, E.,1996, ‘Urban Cadastral Surveys – Reinstatement Principles and Practice’, Proceedings of Seminar'96- Re-Instatement: Principles and Practice. Association of Consulting Surveyors, Queensland. A reinstatement logic for urban cadastral surveys is introduced with a simplified four-part cadastral method. This method also advocates the importance of undertaking a complete search for documentation and pre-analysis of the survey plans.
Chapter Two: Background Aspects to Boundary Surveying
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prima facie evidence of the intention of the parties. This cannot be over emphasised. If the occupation has stood for a long time, provided, of course, that it is on common boundary, they the acquiescence of the parties makes its status as evidence very much stronger. Under the doctrine of contemporanea expositio,67 the court may regard the occupation as evidence of the way in which the original parties interpreted the deed, and thus as first class evidence of their intentions. However, if occupation can be explained away then its importance may be completely displaced and more weight may be given to other "calls". Where a fence or other such monument has been erected in pursuance of an agreement that it shall mark a boundary line between two parcels, it must be taken as a boundary, whether or not it coincides with "deed". 68
The rationale behind Brown’s (1980) comments clearly relate to the notion of
long-standing, undisputed occupation as previously cited in Equitable Building
and Investment C. v. Ross. The hierarchy of evidence "rules" as suggested by
Brown (1980), based on various legal historical cases, are not all encompassing
of all situations. Regardless of the new technology approaches to the field
measurements, the search process for best evidence remains largely the same
even though the methods of measurement improve due to technology
advancements.
Brown (1980) sums up the situation involved resolving ambiguities associated
with a title description and that which was marked on the ground. In making a survey to re-establish the boundaries of land, the first and over-riding aim is to arrive at the intention of the parties expressed in the original documents establishing those boundaries.69
Surveys for new subdivision actions involve traverse measurements routinely
performed to a high level of measurement accuracy. However, new
measurements do not necessarily fix up existing reinstatement problems. New
measurements are useful to reinstatement in the future given the high accuracy
attributable to the measurement descriptions of the intention of the subdivision
action. Therefore, it logically follows that increasing measurement accuracy will
67 contemporanea exposition means interpretation based on the law as it existed at the time an agreement was concluded, rather than the law at the time the dispute arose. Definition derived from http://faculty.rmwc.edu/jabbassi/POL330/ConceptList.htm based on Dictionary of International and Comparative Law by J. Fox, Oceana Publications, 1997. 68 Allan Brown, 1980, Law Relating to Land Boundaries and Surveying. Association of Consulting Surveyors Queensland, pp154-155. 69 Ibid., p154.
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gradually provide an improved aspect of cadastral related positions. This
inference is founded on two assumptions, firstly that consistent reinstatement
approaches continues into the future despite changing measurement technology,
and secondly, a continuity in survey marks and marking standards.
2.3.2 Issues of Integrity
This section introduces the issue of integrity not only in cadastral systems but
also in the symbolism used to communicate the language of surveying at a
practical level. Surveying systems have a particular problem in needing to exist for an indefinite duration. Moreover, surveying systems rely on written records that supposedly refer to facts on the ground at the time the records are made. Accordingly, much depends on the accuracy and integrity of surveyors as recorders of facts. The surveyor’s role within a surveying system includes communication of various facts through marks on the ground and written records.70
Cook (2003) provides a compelling additional issue to the argument of decay
and deterioration of survey information in the context of the non-conclusive use
of coordinate descriptions, thus: The idea that information can deteriorate over time is as much a truism as saying that living things will eventually die. The entropic breakdown of information occurs everywhere. The following examples of breakdown help to illustrate the point: • People may forget things if they make no special efforts or have no
reason to remember them • Information and knowledge may be lost when people die • Paper records may deteriorate as ink fades or paper disintegrates • Electronic records may become lost or corrupted through lack of use or
misuse • Survey marks and monuments will deteriorate over time and the
understandings that people have about these marks and monuments can also be forgotten.
• Languages can fall into disuse and become so-called ‘dead’ languages, especially when they lose their capacity to invent new words to describe new experiences.
Implementing new technology is necessarily a new experience and new vocabulary is an important part of adapting to technological change. In the absence of a sufficient vocabulary, interpersonal communication can fail. This
70 J.S. Cook, 2003, PSB620 Law for Surveyors, Teaching Resources, Lecture 2 – Cadastral Problems Conceptualised as Breakdowns in Communication Processes. School of Design and Built Environment, QUT. Accessed on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/surveying-law/boundaries/02-communication.htm (accessed April 2003)
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leads to failure in the stimulus/response mechanisms needed to control the use of technology in ways that are socially acceptable.71
If the measurement of relationships between ground evidence through field
surveying is considered part of the larger land administration discipline, it is
increasingly important for surveyors to have an understanding of entropic effects
as they apply to land administration. The cadastral surveyor’s search for
evidence is a practical means to quantify the amount of boundary evidence
captured and recorded or conversely little or no evidence found, at a given
moment in time.
Indeed, the evidence placed by the surveyor in conjunction with a survey action
(subdivision or freeholding) has a limited-life caused by various influences as
described in Table 2.3. It is this understanding of losses through entropy
influences that forms the basis for a risk management strategy.
Table 2.3: Effects of deterioration and loss of integrity of survey monuments.72
71 Cook, J.S., 2001, Personal Communication– Cadastral, Geodetic and Other Surveying Systems – Do they Live and Can They Die?, Unpublished Paper (work in progress). School of Design and Built Environment, QUT.
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In recent times, government organisations undertaking risk management analysis
have recognised the potential loss of information contained in paper-based
records. In attempts to minimise risk, the organisations have converted many
public land records to a digital form, with secondary copies archived in another
location for safekeeping in the event of a catastrophic event.73 Physical security
of land administration records and archived materials has gained organisational
importance post the events of September 11, 2001. Archival legislation of public
documents including land administration records fall under the auspices of
Queensland Public Records Act 2002.74
Risk management is a process consisting of well-defined steps that, when taken
in sequence, support better decision making by contributing to a greater insight
into risks and their impacts. It is also about identifying opportunities as it is
about avoiding losses. By adopting effective risk management techniques, the
organisation can help to improve safety, quality and business performance.75
In 2001, the Surveyor General of Victoria, Mr. Keith Bell, provided pointed
comment of managing risks associated with cadastral surveying activities with
an example by comparison to a medical practitioner. When comparing the risk management strategies of land surveyors with other professions such as doctors, lawyers, engineers and accountants, is the Government over-managing the risks or are the requirements for the cadastre greater by necessity? Take for example a general medical practitioner (GP). The GP initially undertakes a long course of university education, followed by a period of internship. Once registered by the relevant State board, the GP may be required to undertake CPD. The GP examines and diagnoses patients and prescribes medication. Generally, the GP has an independent relationship with their client, without any system of checking. In relation to the services provided by the GP, the risk is loss of human life or serious impairment or injury. In comparison, the land surveyor completes a prescribed university degree, followed by a traineeship and examination by the State’s Surveyors Board. Once registered, the Surveyors Board may require CPD. Those outputs of the surveyor which are required to be submitted to Land Registry, will be examined by qualified government staff, unless an accreditation system is in place. Many of the recent jurisdictional reviews into the regulation of land surveying undoubtedly considered whether governments are too risk averse.
72 Ibid. 73 Issues of records management, tacit knowledge and disaster recovery plans (DRP) discussed by Kim Sbarcea, 2001, Counting the Knowledge Cost – the untold loss of the World Trade Centre attacks, Image and Data Manager magazine Asia-Pacific, published by Gerard Knapp, Sydney, pp.18-21, December 2001. 74 Queensland Government, 2002, Public Records Act 2002 -April 2002. Available on-line Internet via index http://www.legislation.qld.gov.au/OQPChome.htm (accessed May 2002) 75 Standards Australia, 2002, ‘What is Risk Management?’ a Standards Australia portal. Available on-line Internet http://www.riskmanagement.com.au/ (accessed Dec 2002)
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However, surveyors have a responsibility not only to their clients but also to the adjoining owners, the local government, referral authorities, the Crown’s registration agencies, and the community who will rely on the integrity of their surveys now and into the future. It may be argued that a surveyor’s responsibilities are unique compared to the responsibilities of other professions. It is incumbent on a surveyor to be impartial to ensure the maintenance of public confidence and trust in the actions of a surveyor.76
Risk management is a recent trend in management style. As such, further
investigation and examination of risk management strategies applied to cadastral
surveying and mapping is required at an organisational level. Risk management
strategies applied to cadastral surveying and mapping functions should strive to
improve integrity of the cadastre through additional redundancy and minimising
entropy influences. Some of the comments and discussion developed in later
chapters of this thesis identify risks associated with coordinate based technology
and highlight certain opportunities that can be made by the State of Queensland
in benefiting the practitioner and the community.
This thesis examines new measurement technology applied to cadastral survey
applications and organisation with an important review of these background-
guiding principles. In the absence of contrary information, it is not until point 7
of Browns (1980) guide that implications of bearings and distances, derived from
redundant GPS measurements forming three-dimensional vectors, will influence
the reinstatement process in absence of a higher weight placed on other
evidence. These principles arguably accept some localised movement of ground
survey marks in the overall reinstatement process. However, an element of
evidence may be accorded particular weight depending on the circumstances
when viewed holistically. Justice Griffith made this original assertion in
Overland v Lenehan, thus: They may be summed up by saying that most weight should be given to those points on which the parties at the time were least likely to be mistaken.77
76 Bell K. and Cleary M., 2001, ‘Protecting the Integrity of Victoria’s Cadastre – Managing the Risks’. Proceedings of 2001 - A Spatial Odyssey including 42nd Australian Surveyors Congress, p.7, Institution of Surveyors Australia, Brisbane Convention and Exhibition Centre. 77 Supreme Court of Queensland, 1901, Overland v Lenehan,, The Queensland Law Journal, Volume 11, at p.66.
Chapter Two: Background Aspects to Boundary Surveying
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It is these critical comments made by Griffith that are the key to this cadastral
integrity argument.
It is at this stage of the argument that a distinction in coordinate representation is
required. Coordinates produced as a by-product from bearings and distances
from electronic total stations become secondary in derivation to the metric
measurement information. GPS derived coordinates are different as they are a
product of carrier-phase trilateration distance measurements made to orbiting
satellites. Relative positions are described as a three-dimensional vector
displacement between two points. Conveniently, coordinates describe or
summarise locations of the points at either end of the vector.
A reliable cadastre arguably relies on the strength inherent in the surveying
infrastructure. Any decline or weakness of the surveying infrastructure
potentially creates greater opportunity for errors and inconsistencies to occur.
Land surveyors must be able to depend on the accuracy and integrity of the
infrastructure in order for their surveys to support the integrity of the state
cadastre. The influence of solely relying on coordinate information alone as a
description to cadastral evidence with disregard to attached qualifications about
the knowledge of methods, techniques and relativities to make the position
determination is strongly inadvisable.
Chapter Two: Background Aspects to Boundary Surveying
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2.4 Cadastral Survey Legislation and Measurements The purpose of this section is to examine the legislative statements relating to
quantitative measurements made in relation to cadastral activities. Tenuous links
and inferences are made relating to the issue surrounding suitable use of GPS
derived positioning methods depending on the interpretation of the legislative
statements. It is acknowledged that legislative amendments and regulations
lapse behind community expectations on occasions.
Survey measurement accuracy requirements and approaches to calibration and
standardisation were conveniently summated by a study undertaken by Boey and
Parker (1996). This study and review is some seven-years old at the time of
thesis investigation, but the on-going literature review has failed to locate an
equivalent, in-depth published summary of state measurement and legislative
requirements. The arguments as to the use of GPS measurements for cadastral
purposes are based on the 1996 summary results (updated in 1999 by Boey).
This investigation believes that this is still a valid assumption given the
timeframe between legislative review processes relative to survey activities.
Boey & Parker (1996) conducted a study to review all the survey legislation and
complimentary publications relating to the practice of cadastral surveying in
Australia. The major aim of that review appeared to ascertain whether or not the
existing legislation is able to handle the use of new measurement technology,
such as coordinate descriptions of position from GPS, and associated techniques
for cadastral surveying. Boey further published more updated details on this
issue in 1999, from which the following tables and contribution provide further
information towards the topic. This was undertaken prior to the introduction of a
recognised-value of position by the National Standards Commission
(Australia).78
78 National Standards Commission (Australia), 2001, Determinations of Recognised-value Standards of Measurement, Other Publications: Determinations, Sydney, NSW, August 2001 6pp. Available for download via Internet http://www.nsc.gov.au/PAGES/Info/info_sales_other.html (accessed December 2001)
Chapter Two: Background Aspects to Boundary Surveying
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Direct Copy of Boey’s 1999 Summary of Survey Legislation in Australia
Table 2.4: Boey’s (1999) summary of survey legislation and complementary publications in Australia.79
These summary tables have been included because they influence upon the
practicalities of local jurisdictions that will need to consider these issues in the
next few years. This logically follows on from the preceding arguments and
demonstrates disparity between state jurisdictions on the issue of calibration and
standardisation of measuring equipment, including GPS measuring systems. This
79Direct copy of table of reviewed survey legislation from Boey, S.S., 1999, A Model for Establishing the Legal Traceability of GPS Measurements for Cadastral Surveying in Australia, UNISURV Report, S-55, page 63, November 1999, School of Geomatic Engineering - University of New South Wales.
Chapter Two: Background Aspects to Boundary Surveying
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directly relates to the dissertation hypothesis section in considering suitably
recognised by authorities and integrity arguments.
The evolution of survey legislation in Australia has generally been influenced by
historical factors along with local cadastral issues that have, in turn, aligned
upon variables such as: the manner in which a jurisdiction was first settled, land development policies, government of the day and to a certain extent, availability of surveying resources and infrastructure. Further, post-World War II developments such as: survey co-ordination, survey integration, multipurpose cadastres, creation of digital cadastral databases (DCDB) for spatial information systems and prospects of deregulation have dominated many cadastral reform initiatives.80
The following tables describe the summary of statutory requirements relating to
calibration and standardisation of survey equipment, survey methods and
accuracy standards for each state jurisdiction. It is noted that the term calibration
has one main objective to ensure that results of measurements are made in terms
of the Australian legal units of measurement.
In furthering this line of inquiry, Boey (1999) adds further comments that justify
this assertion, such -
Calibration ensures that a measuring system: • can comply with the required accuracy specifications; and • can retain its calibration during its operating life.
In general, most survey legislation in Australia requires survey equipment to be calibrated and standardised. In addition, the equipment is required to be maintained routinely, inter alia, in order to preserve the validity of the calibration.81
The summary tables below arguably demonstrate very little uniformity in the
manner in which the current requirements are prescribed, since they vary from
very specific requirements in New South Wales to the non-prescriptive, such as
those of South Australia.
80 Ibid., p.63 81 Ibid., p.67
Chapter Two: Background Aspects to Boundary Surveying
Table 2.5: Boey’s (1999) summary of survey statutory requirements by jurisdictions.83
82 Queensland Government, 1978, Queensland Surveyors Act 1977, can be found on-line Internet http://www.legislation.qld.gov.au/LEGISLTN/CURRENT/S/SurveyorsA77_02A_.pdf (accessed December 2000) Note that the electronic versions of legislation (including endnotes) on this site are not recognised as the official or authorised version of legislation.
Chapter Two: Background Aspects to Boundary Surveying
83Direct copy of table from Boey, S.S., 1999, A Model for Establishing the Legal Traceability of GPS Measurements for Cadastral Surveying in Australia, UNISURV Report, S-55, page 64, November 1999, School of Geomatic Engineering - University of New South Wales.
Chapter Two: Background Aspects to Boundary Surveying
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Notations: * The tabulated standards of accuracy are those obtained from the cadastral survey legislation, other supporting legislation (not included in this review), such as the Survey Coordination legislation, may also prescribe additional accuracy standards for the appropriate purposes. n – number of angles A - Adelaide City Core District σ - standard deviation B - Commercial and Adelaide City Frame & Residential delta E - misclosure in easting C - Urban delta N - misclosure in northing D – Rural F – either 50 or 140 depending on the type of marks compared S – the distance between 2 marks
Table 2.6: Boey’s summary of accuracy standards in Australian States.84
84Ibid., p.65.
Chapter Two: Background Aspects to Boundary Surveying
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Summary of calibration and standardisation requirements in Australia
Chapter Two: Background Aspects to Boundary Surveying
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Table 2.7: Boey’s (1999) summary of calibration and standardisation requirements in Australia.85
One of the major conclusions of Boey and Parker’s (1996) review of cadastral
legislation and requirements was- ..... currently there are legislative requirements that would preclude the use of satellite-based technology, such as GPS, in a cadastral survey. In particular these requirements relate to the need to: • calibrate and standardize survey equipment • verify survey measurements • comply with accuracy standards that may be outmoded and inappropriate86
Under the present national measurement system to achieve legal traceability,
units of measurement must be defined, a standard of measurement must be
available from a comparison perspective, and the traceability chain must be well-
defined and capable of clear documentation.
In the context of GPS methods, the specific measurements that are of particular
interest to cadastral surveying are resulting three-dimensional positions and the
derived vector projected back to a plain local survey. Unlike the physical
quantity of length, position is not a defined and verified physical quantity in the
85Boey, S.S., 1999, ‘A Model for Establishing the Legal Traceability of GPS Measurements for Cadastral Surveying in Australia,’ UNISURV Report, S-55, page 67, November 1999, School of Geomatic Engineering - University of New South Wales. 86 Boey, S.S., and Parker, J.R.,1996, 'A review of current Australian survey legislation in the face of modern measuring technology.' The Australian Surveyor. Vol.41, no.4 December, page 286.
Chapter Two: Background Aspects to Boundary Surveying
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National Measurement Act 1960. This situation has however recently changed
with three-dimensional position now given some status as a recognised-value
standard relative to the AFN by the National Standards Commission.87 The
verification of a three-dimensional position with time has yet to be tested by a
verification authority.88
This situation clearly influences the suitable recognised by authorities
component of the hypothesis under consideration. The national authority is
actively working to provide guidance on this issue, however at the time of
completion of this thesis work, a final acceptable result has not been published
nationally.
2.5 Changing Nature of Datums
The premise of introducing a measurement-based information system within the
confines of local controlled cadastral areas requires some examination of the
historical aspects of datums and the changing nature of national control survey
networks. It is these relative comparisons to the various datums at a particular
point in time that has affected the linkage between local and geodetic surveys
over the Australian mainland continent. The datum changes that have occurred at
a national level include:
• Clark (pre 1966) and other astronomically determined datums;
• Australian Geodetic Datum 1966 (AGD66) -- Australian Map Grid 1966
(AMG66);
• Australian Geodetic Datum 1984 (AGD84) -- Australian Map Grid 1984
(AMG84);
87Recently, as at March 2003. National Standards Commission (Australia), 2001, Determinations of Recognised-value Standards of Measurement, Other Publications: Determinations ,Sydney, NSW, August 2001 6pp. Available for download via Internet http://www.nsc.gov.au/PAGES/Info/info_sales_other.html (accessed December 2001) 88 Further discussion on this issue is contained in chapter 6, section 2 of this thesis.
Chapter Two: Background Aspects to Boundary Surveying
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• Geocentric Datum Australia 1994 (GDA94) -- Map Grid of Australia
1994 (MGA94)89 based on uniform GPS observation campaign.
Implementation from 1/1/2000.
The primary influences of the first three datums were to improve the previous
national control networks with respect to new foundation modelling information
and its associated data quality. The Australian datum has evolved to reflect the
best model at the time of the ellipsoid of this region for geodetic and mapping
purposes.
The adoption of AGD and the introduction of AMG were events ‘of major
national significance’.90 Of significant importance were the adoption of AGD66
and the start of metrication in Australia. The purpose for this arguably massive
change to introduce AGD66 was to produce: ...a homogeneous system of coordinates for geodetic survey station all over Australian (and Papua New Guinea), free from discontinuities caused by changes of origin. Coordinates on the Australian Geodetic Datum provide a firm foundation on which lower order surveys and all mapping can be based; furthermore they provide a basis for a point reference system, on which any point in Australia ……….can be described in precise and unambiguous terms.91
Literature reviews showed that between the years 1858 and 1966 geodetic
surveys in Australia were computed on either a State or regional basis using no
fewer than four different spheroids and as many as twenty coordinate origins.
However, the values of Clark’s parameters appeared to be adopted in many
applications.92 The literature of the time suggested that the larger States
employed two or more origins simultaneously and various values adopted for the
imperial system of units of length at the time.93
89 Note: Map Grid of Australia (MGA94) was implemented from 1st January 2000. Refer to GDA technical manual online Internet http://www.anzlic.org.au/icsm/gdatm/index.html (accessed October 1999) 90 Lines, John D., 1992, Australia on Paper – The Story of Australian Mapping. p.228. 91 National Mapping Council of Australia,1972, The Australian Map Grid Technical Manual Special Publication number 7, National Mapping Council of Australia, Australian Government Publishing Service Canberra 1972, p.1. 92 Clark, David, 1948, Plane and Geodetic Surveying for Engineers – Volume Two, Higher Surveying. 3rd edition 2nd reprint 1948. Published by Constable and Company London. RMW office. 93 Synthesised from comments made by John Lines in Chapter 11, The Renaissance of Geodetic Surveying, AND the GDA Technical Manual background information notes Section 1.
Chapter Two: Background Aspects to Boundary Surveying
53
Of historical interest is reflection upon the comments and development of
geodetic survey activities in Australia during the post-war period as depicted in
the work of John Lines (1992). The advent of the Geodimeter brand Electronic
Distance Measurement (EDM) device into Australian geodetic survey activities
was another technology milestone in improving precision of geodetic networks
from 1954 onwards.94
As global and celestial measurement technology improves, the geo-science
community will strive to improve modelling of the variables of our planet and its
spatial relationships across time. Because of this improved modelling, the
Australian surveying industry is likely to see another generation of datum
change.
The success of implementing a proposed datum change to a country or region
every X years for example, can be summarised by the following points:
♦ The political will to make it happen;
♦ The technical efficiency of change and the technical details associated with
it;
♦ The economic advantages - is there a benefit to be realised in doing
something as opposed to doing nothing at all.
The issue of change management arises when implementing a datum change
whereby the benefits of implementation need to clearly outweigh the benefits of
doing nothing to the aging datum and maintaining the status quo.
2.5.1 Early Design of National Geodetic Networks
The first designs gained an enhanced status in 1948 when the National Mapping
Council agreed to a programme of National Geodetic Surveys. These national
surveys commenced with provisional specifications for horizontal and vertical
control surveys and the initial outline for the Australian geodetic network was
borne.95 Lines (1992) comments that the programme reflected the philosophy of
concentration of survey efforts in more densely settled areas and the better 94John Lines provides an interesting commentary on the chronology of EDM technology in use at National Mapping Council during the late 1950s, Australia on Paper – The Story of Australian Mapping, pp..217-226.
Chapter Two: Background Aspects to Boundary Surveying
54
agricultural and pastoral regions. The programme required only a minimum of
trans-continental ties to assist with the determination of a suitable spheroid for
Australia.
The following figures provide a graphical approach to the development of the
Geodetic Network in Australia. Of interest to this thesis is the obvious lack of
geodetic survey control in rural areas to support cadastral mapping functions.
Lines (1992) publication includes further diagrams of points in time showing the
development of control networks during 1950s to late 1970s. As observed from
the following two graphics, the control networks mainly resided around
population centres and inland NSW.
Figure 2.3 National Geodetic Surveys 1945.96
95 Ibid., p215.
Chapter Two: Background Aspects to Boundary Surveying
55
Figure 2.4 Geodetic Control Surveys 197597
96 Modified and enhanced from Lines, John D., 1992, Australia on Paper – The Story of Australian Mapping, p.211. 97 Ibid., p.237.
Chapter Two: Background Aspects to Boundary Surveying
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Figure 2.5 Geodetic Control Surveys in Qld 1975.98
Of historical interest is that minimal work of first-order quality was conducted
across the continent until 1954 when Lieutenant-Colonel H.A. Johnson joined
National Mapping as the senior geodetic surveyor.99 Lines commemorates the
work of Johnson in saying that:
98 Modified and enhanced from Figure 2.4. Ibid., p.237. 99 Howard A. Johnson MBE,LS,FIS Aust, MAIC.
Chapter Two: Background Aspects to Boundary Surveying
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In the writer’s [John Lines] estimation, he stood alone as the surveyor most likely, because of personal dedication and expertise, to pursue the national geodetic survey to finality in the knowledge that whatever commitment fell to National Mapping, and it transpired to be by far the major commitment of all the contributors, National Mapping would not be found wanting in bringing this great national enterprise to a successful conclusion.100
In 1971, the National Mapping Council published the Australian Map Grid
Technical Manual, no.7. About this time the National Mapping council become
aware of the variability and dynamism of the defining parameters comprising the
elements of the national datum actually change over time. It was previously
assumed that the parameters where reasonable constant in magnitude. A national
measurement-based geodetic control system will arguably lead to updating of
this variable data in a technically efficient and cost-effective manner by inserting
more up-to-date measurement data into the control system to produce improved
up-to-date knowledge. This idea has many similarities with the concept of a
dynamic datum as discussed in later chapter.
At section 1.2.* of the AMG technical manual, number seven, two statements of
interest to this dynamism argument are presented. Firstly that: In 1966, the minor axis of the spheroid was defined to be parallel to the Earth’s mean axis of rotation at the start of 1962. In 1970, the National Mapping Council decided to adopt the conventional International Origin, previously known as the mean pole of 1901-05, for the direction of the minor axis. The council decided that no change in the 1966 coordinates was necessary. ……..The position of the centre of the spheroid (Australian National Spheroid) ANS is defined by the following coordinates of Johnston Geodetic Station {Numerical Data etc}.101
The 1971 manual further acknowledges the possibility of future re-adjustment
and the potential confusion of stating coordinates only without quantifying a
source: ……In future years, it may well be that the geodetic surveys in Australia will be readjusted, so that scientists and others interested in the most accurate possible coordinates and distances in Australia may take advantage of all the most recent observation. For mapping, and for references on the Australian Map Grid, it is intended to retain coordinates in terms of the 1966 adjustment. If it becomes necessary to avoid ambiguity, other coordinates should be qualified by a statement of their source.102
100 Lines, John D.,1992, Australia on Paper – The Story of Australian Mapping 1992 p.215. 101 National Mapping Council of Australia, 1972, The Australian Map Grid Technical Manual Special Publication number 7, Australian Government Publishing Service Canberra 1972, p.2 102 National Mapping Council of Australia, 1972, The Australian Map Grid Technical Manual Special Publication number 7, Australian Government Publishing Service Canberra 1972, p.2.
Chapter Two: Background Aspects to Boundary Surveying
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The second statement of interest to this dynamism argument is the special
footnote reference to defining parameters of the Australian National Spheroid
(ANS). That is: The International Union of Geodesy and Geophysics at its meeting in Lucerne in 1967 adopted the Reference Ellipsoid 1967, which is very similar but not identical to the Australian National Spheroid:103
[Numerical comparisons in the form of a table given for 1/f and e2 values.]
The ANS special reference statement continues with – The difference is trivial, amounting to only 0.07 metres in the minor axis. But it is not possible to formally adopt the Reference Ellipsoid 1967 without recompute all AGD coordinates.104
Clearly, this is a short way of stating that the AGD coordinates are already out of
date one-year after the introduction of AGD66. National Mapping Council
further conceded that based on the current knowledge of earth rotation
parameters, the dynamics of datums is computational inefficient to recompute
even on a yearly basis for a whole nation.105
These technical admissions support the central argument that the Australian
region is constantly moving with some continual internal changes, not only in a
physical sense, but also in relativistic terms (datum changes and refinements).
Australian research efforts can draw upon geographical regions that do suffer
from large detectable ground movements and Australian campaigns to measure
them.106 Additionally overseas research and scientific observations on this topic
contribute knowledge towards how best to tackle the complex issues of dynamic
datums in the context of global geodetic datums.107
103 Ibid., p1. part 1.2.1. 104 Ibid.,p1. footnote. 105 Inferred by statements made at 1.2.2 and 1.2.4 Ibid.,p.2. 106 Dawson, John, 2002, South West Seismic Zone 2002- GPS Analysis, GPS data analysis of 300km by 200km area of South West of Western Australia, published online by Geoscience Australia GPS Geodetic Technical Reports www.ga.gov.au/geodesy/reports/gps/ (accessed July 2004). 107 Such as the New Zealand discussions prior to implementation of a new national datum in light of data relating to continental plate motions presented by Denys, P & Cross,P. 1996, The Role of IGS and ITRF data products in the definition and maintenance of National Coordinate Systems. New Zealand Surveyor No286, p14-19, April 1996.
Chapter Two: Background Aspects to Boundary Surveying
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Figure 2.6: 100km Geodetic Infrastructure Network over Queensland 1999. The 100km GPS network (class 2A) was subject to an unconstrained GDA adjustment, which produced excellent results with a standard deviation on baselines at 5mm +0.5ppm.108
As human knowledge better understands these continual changes and the ability
to measure not just local parameters, but also global and planetary variables, we
gradually refine and better model the situation as time proceeds. The Queensland
100km geodetic infrastructure (observed using high precision GPS control
techniques) assists in refining local datum parameters and contributes to the
geocentric model of this region.
In considering the original hypothesis that property boundary surveys could be
achieved by relative GPS techniques, the linkage to suitable coordinated
reference framework (state/national and global datum definitions) is clearly of
importance.
108 Cowie, M, 1999, ‘The Queensland Geodetic Network - Adjusting to GDA94’, Proceeding of Survey'99 Congress, Queensland Institution of Engineering and Mining Surveyors Australia. Sunshine Coast, October. Page 14.
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2.6 Description and Limitations of Coordinate Based Positions A distinction in source coordinate representations is required when discussing
GPS methods and total station traverse methods. Coordinates produced from
bearings and distances from electronic total stations become secondary in
derivation to the metric measurement information. Coordinates derived from
GPS methods are a product of carrier-phase trilateration distance measurements
made to orbiting satellites with relative positions described as a three-
dimensional vector displacement between coordinates representing points.
Coordinates can be useful to a wide range of technical users to describe a three-
dimensional position at a given point in time in relation to a recognised datum.
However, serious problems can be associated with these coordinates when used
as a sole description for boundary location purposes. Cook (1994) raises some
important issues associated with communicating land boundary coordinate data,
such that:
• Coordinates should be regarded as prima-facie evidence only of boundary location and no attempt should be made to regard them as conclusive evidence.
• The use of coordinates on paper documents and in interpersonal communication should be minimised and controlled. Land boundary data in the form of coordinates contains no inherent redundancy capable of testing its veracity and a single error in a single digit may be undetectable yet it may have disastrous consequences.
• Coordinates should not appear on documents unless the date of the relevant coordinates adjustment also appears along with a warning that co-ordinate information is subject to variation with successive updates of information.
• Consideration should be given to procedures for disseminating updated information on the basis of the special needs of the previous users, continuing users and prospective users of land boundary information.109
These issues highlight problems of communication of coordinate land boundary
information. The proposal of introducing local controlled areas based on
geological sub-plates provides further support to the argument of a cadastral
management strategy based on primary measurements that incorporate the latest
information for the automated communication of coordinate data. The central
argument is that coordinates describing a position are regarded as tentative, at a
109 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Chapter 4 page 132. Selected chapters also available on-line Internet http://www.plas.bee.qut.edu.au/www_jsc/jscpubs.htm#dissertation (November 2000).
Chapter Two: Background Aspects to Boundary Surveying
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point in time, in communication of a location and not regarded as guaranteed or
fixed, be that relative or absolute in nature.
Other concerns encountered by organisations with co-ordinate based cadastral
systems relate to maintaining the quality of the coordinates database. These
concerns are important when users of DCDB data are demanding higher
accuracy for applications not originally intended of coordinates collected by
digitising methods or computed from measurements of low quality.
The determination of cadastral boundaries involves a range of evidence assessed
in accordance with well-documented principles of reinstatement. The description
of a parcel includes the metes and bounds as described on the survey plan and
referenced on the Deed of Grant and/or Certificate of Title. This information is
accurate at the time of survey for which two-dimensional coordinates can
conveniently provide a summary representation in a local area.
A specific issue that appears from a review of the literature is the updating of a
coordinate database with new measurements. Central to this issue is the
incompatible accuracies between the coordinates and the measurements. New
measurements acquired using modern high precision instruments are usually of
higher quality than the existing coordinates. Lambert introduced and discussed
this management idea in 1981.110 A common assumption exists that high quality
geodetic networks are in place. However, many of the updating methods fail to
take into consideration the quality of existing coordinate values of the cadastre
and the new measurements. As a result, the variable accuracy information of the
new measurements that are now available in the form of new coordinate
representations is potentially wasted.
The surveying profession for a number of years has discussed the desirability of
a coordinated cadastre along with the potential benefits to the community at
large. A true coordinated cadastre would be a cadastre where strong links exist
110 Lambert, B.P.,1981, 'Australian geodetic coordinates - keeping up with the times'. The Australian Surveyor, vol..30, no.8, December, p.491.
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not only between the parcels or properties but also to a common reference
framework that covered the entire range of the cadastre. The coordinated
cadastre should represent the positions of corner points in the cadastre to a
highly acceptable level of accuracy.
According to Baker’s (1991) research, this accuracy requirement would vary
between distinct urban and rural areas but, generally, should not exceed
0.10metres in an urban environment and 0.5metres in a rural environment. This
level of accuracy would imply unambiguous reinstatement of corner points.111
Baker statement implies this refers to planimetric accuracy only. At 1999, the
only states with an accuracy statement relating to a position were South Australia
and Tasmania, with values of 0.15 and 0.06 metres respectively. Other state
jurisdictional requirements relating to linear and angular closure and
measurements accuracy have been summarised in table 2.6.
According to Stock’s (1998) research results investigating accuracy requirements
for rural land parcels boundaries in Queensland, there was some indication that
rural landowners required or desired land boundary accuracy of +/-0.2 m while
utility and local authorities in rural areas have requirements of about +/-0.5m.112
The metes provide a spatial representation of a parcel, similar in relative spatial
accuracy to diagrams, as they exist on Deed of Grant and Certificate of Titles.
The literature review of organizations that have progressed towards full
implementation of a survey accurate cadastre incorporating parcel dimensions
have shown a common characterised benefit by improved relative spatial
accuracy.
Another related issue is that modern GPS techniques can supply high quality
three-dimensional data whereas the cadastre is normally only associated with a
two-dimensional representation. Clearly, a uniform description of accuracy is
required when making comparisons of multi-dimensional data. Although in
111 Baker, K., 1991, ‘Positional Accuracy Considerations for a Digital Cadastral Data Base’, Proceedings of Symposium on Spatial Database Accuracy, Department of Surveying and Land Information, The University of Melbourne, June, p.46. 112 Stock, K.M., 1998, ‘Accuracy Requirements for Rural Land Parcel Boundaries’, The Australian Surveyor, Vol.43, No.3, pp165-171. This research was conducted in the Linthorpe Valley project area, Pittsworth Darling Downs region. Results based on interviews and questionnaire for approximately 110 owners covering almost 330 rural land parcels.
Chapter Two: Background Aspects to Boundary Surveying
63
urban areas, an increasing amount of assignment of rights and obligations
associated with volumetric surveys relating to three-dimensional spaces is
occurring. Examples of this type of survey are those associated with:
telecommunication towers; pedestrian pathways over and through road reserves
to provide connectable links to private lands; and large sporting arenas
constructed partial over and above land reserved for the purposes of a road or
parklands.
The primary issue of controversy is the sole use of coordinates as evidence of
boundary location. Cook (2003) provides qualification of redundancy in
transmission and communication to the current boundary location situation, thus: Generally, no problem exists in saying that a coordinate is evidence of a boundary location. Nor is there a problem if a Digital Cadastral Data Base (a DCDB) produces coordinates that are regarded as prima facie as evidence. The problem arises when enthusiastic amateurs try to elevate the status of coordinates to conclusive evidence and deny admissibility of other evidence. The need for redundancy is greatest not so much where the risk of error is greatest but where the consequences of an error are greatest. In the case of the Air New Zealand tragedy, the consequences of an error in using coordinates when otherwise flying blind were the deaths of 257 people. Generally, no reason exists for not allowing redundancy to provide systematic checking of all important information. The idea of coordinates as conclusive evidence – to the exclusion of all other evidence including the extrinsic evidence of boundary evidence on the ground – is certainly unwise and is probably unacceptable politically.113
The evolving issue of maritime cadastres proposes that coordinate descriptions
are used to provide a definition of Territorial Sea Baselines (TSB) with offset
distances to the actual maritime boundary. This application issue is under
investigation by spatial science researchers from University of Melbourne.114 An
issue of importance is one of legal status of coordinate descriptions in the
absence of ground monumentation in a maritime environment.
113 Cook, J.S., 2003, PSB620 Law for Surveyors, Teaching Resources, Lecture 3 – Entropy and Breakdown in Surveying and Mapping Information. School of Design and Built Environment, QUT. Accessed on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/surveying-law/boundaries/03-Entropy.htm (accessed April 2003) 114 University of Melbourne, 2003, The ARC Marine Cadastre Pilot Project, website index, Department of Geomatics, The University of Melbourne, available online Internet http://www.sli.unimelb.edu.au/maritime/ (accessed May 2003)
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2.7 Issues of Spatial Information Systems The most recent datum changes for the Australian region evolved from an
improved understanding and improved mathematical models of our planet from a
global context. The key advantages of the GDA over Australia’s AGD84 are that
the former is:
• Extremely compatible with satellite-based navigation and point survey
systems such as the Global Positioning System (GPS);
• Compatibility with major regional and international geographic
information systems.115
The linkage between Australian Spatial Data Infrastructure (ASDI) and GDA is
that all data themes are supplied to users in GDA horizontal coordinates. This
should allow users of ASDI to integrate their data with other information
systems and communication technologies. GDA has been the datum put forward
as the best to use for minimising confusion of users and to provide maximum
accuracy where high precision is required.
In the early 1990s, many local government authorities were required to
implement and develop their Asset Management Information Systems. These
systems generally linked by some mechanism to the local authority’s Land
Information System (LIS). The Digital Cadastral Data Base (DCDB) typically
provided the linking mechanism on which the assets requiring management are
mapped and described relative to the surrounding apparent property boundaries.
Dawson and Hayes (1993) provide comment on the importance of GPS control
to residential land-estate developments, thus: A majority of Local Authorities had realised even before its announcement that, to meet the requirement of AAS27,116 a Geographic Information System (GIS) would provide an ideal tool for the administration and maintenance of assets. GIS has the
115 ICSM, 1999, Going Geocentric – Understanding Australia’s New Coordinates Video media production -10 minutes duration, produced by ICSM Intergovernmental Committee on Surveying and Mapping, June 1999. 116 The accounting profession has recognised the importance of asset management through the formulation of Australian Accounting Standard 27 (AAS27) - Financial Reporting by Local Governments and its adoption as a basis for the financial regulations supporting the revised Local Government Act. Hughes, A., 1993, ‘Asset Management- An Overview of the Queensland Scene (Water Supply and Sewerage)’. Proceedings of Queensland University of Technology Surveying Winter School: Asset Management in Local Authorities. Brisbane, September 1993.
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facilities for ease of identification of immovable objects and the display of inter-relationships whilst providing links to the textual data base. …..A truly integrated GIS will be based on a network of GPS control points. The costs of providing coordinated spatial data for an estate development were investigated by Murphy (1992).117 It was shown that:
“…GPS combined with modern equipment and software already used on estates can provide a cheap, quick and simple method to derive this information at source.”
The costs to provide the necessary GPS coordination to an estate ranged from 0.3% of total estate development costs for a 30lot subdivision through to 0.03% for a 400 lot subdivision.118 …GIS, the integrating spatial technology, will no doubt speed the march towards extinction for some because it places incredible power in the hands of users other than surveyors. It may, however, also represent a path to survival for those surveyors who are willing and able to adapt to and exploit the new technologies. 119
Granger (1993) believes that surveyors must come to terms with four critical
factors if they are able to select the ‘GIS route to industry salvation’, thus: • The return to an appreciation that spatial science relates to the real world of
three dimensions, or four by including the temporal dimension, rather than the two dimensional world of the cadastre which leads to a greater degree of linkage between cadastral and topographic information;
• a realisation that there is more to spatial science than data capture as the largely untapped potential of GIS lies in its application to solve real world problems and to the decision making process in most aspects of human endeavour;
• absolute spatial accuracy is not what most consumers of spatial information want or need, that relative accuracy is good enough;
• the cultural problem that surveyors seem to have in that they believe they have a monopoly on spatial information.120
A driving issue in proposing a Measurement-Based Land Information System
(MBLIS) is that cadastral surveys gather information that has a broader
application in multi-purpose land administration and land management systems.
Current government policy appears to be driven towards completion of statewide
DCDB coverage among many local authorities, with support from the
Department of Natural Resources and Mines (NR&M), to address the needs of
improved spatial accuracy.
117 Murphy, P.J., 1992,‘The Role of GPS as a Tool for the Coordination of Spatial Data Involved in Estate Development’, Proceedings of Queensland University of Technology Surveying Winter School, School of Surveying, Brisbane, July 1992. 118 A valid point is that percentage costs of 1992 are somewhat different to 2002 percentage costs due to changes to Survey Coordination legislation and Integrated Planning Act legislation. Increasing, local authorities are adopting principles of sustainability which can add varying costs to a land development project depending on land characteristics, for example dealing effectively with acid sulphate soils. 119 Dawson, Peter, & Hayes John, 1993, ‘Asset Measurement for Asset Management: New Opportunities for Surveyors?’ Proceedings of Queensland University of Technology Surveying Winter School: Asset Management in Local Authorities. Brisbane, September 1993. 120 Granger, K.,1993, ‘Dispensable Dinosaurs? Some Outside Observations on the Surveying Profession’, The Queensland Surveyors Bulletin, August 1993, pp.8-10. Cited in Dawson and Hayes 1993.
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A review of literature on the topic of digital cadastral databases concurs that the
current thinking towards levels of accuracy in a digital cadastral database
arguably contains several possible levels of accuracy:
• Digitising from best available cadastral mapping with sparse survey
control - this appears to have been the status of base level DCDB
around the late 1980s.
• Introduction of extra control but still using digitised information - this
is a typical form of upgrade and often described and referred to as an
upgraded DCDB. In general, the accuracy is within +/- 1mm of map
scale, except those parcels which were digitised from old Parish
maps.121
• Use of bearing and distance cadastral survey information (and on some
occasions other engineering data) with supplementary amounts of
auxiliary survey control which is rigorously adjusted, typically using a
least squares approach - this is often described and referred to as a
“survey accurate DCDB”. It is important to distinguish that this
approach is purely a mathematical approach with the resulting
information not directly useful for cadastral reinstatement because the
adjustment of boundaries ignores other cadastral reinstatement rules
such as long-standing occupation. Examples of this approach include
the 1997 Gold Coast City Council DCDB upgrading project.122
• The approach of best evidence of cadastral boundary location - this is
the typical coordinated cadastre underpinning a legal coordinated
cadastre. This approach is generally thought of as more than a purely
mathematical adjustment and requires expert interpolation at times
with rules and criteria based decision support of the information. Early
examples of this approach include survey work reported by Borchardt
and Lunnay (1992) and further by Borchardt and Mollison (1993),
with respect to the South Australian experience.123
121 Wan,W.Y., and Williamson, I.P., 1995, ‘A Review of the Digital Cadastral Databases in Australia and New Zealand’, The Australian Surveyor, Vol.40 No.1, pages 41-52. 122 Veenendaal, H., 1997, ‘Gold Coast City Council DCDB Upgrade’, Q-Cadastre, Issue No.7, pp.6-7, March 1997. 123 Borchardt,D., and Lunnay,C., 1992, ‘Underpinning a Legal Coordinated Cadastre - The South Australian Experience’, paper presented ISA northern group meeting, Cairns, May 1992. 16 pages. Also. Borchardt,D., and Mollison, R., 1993, ‘GPS Kinematic Surveying in High Production Mode’, Proceedings of 35th Australian Surveyors Congress, Darwin. Institution of Surveyors Australia, pages 94-111, May, 1993. This paper
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Clearly from a coordinate database context, the resources required towards
achieving the last option are considerably less when reliable coordinates
introduced at source, as part of the field surveying process, are soundly
considered. Murphy (1992) and Collins’ (1992) independent conclusions from
applied investigations into using GPS for residential land-estate development
work further support this line of inquiry.124
Recent initiatives include the concepts of Spatial Data Infrastructures (SDI) and
the National Cadastral database, with its library of uniform descriptions, for
collectively organising seven independent state government efforts into one
standardised and unified organisation of spatial information.125 The benefits of
these efforts can be realised and nurtured through a stable and commonly agreed
datum with supporting coordinate transformations from older datums to one
consistent geocentric datum.
discusses the use of kinematic GPS for cadastral traversing and coordination of survey monumentation in rural environments 124 Murphy, P.J., 1992, 'The Role of GPS as a Tool for the Coordination of Spatial Data Involved in Estate Development', Proceedings of Queensland University of Technology Surveying Winter School, School of Surveying, Brisbane. Also, Collins, B., 1992, ‘GPS - The Next Big Thing in Cadastral Mapping? The Application of the Global Positioning System (GPS) for the Coordination of existing Cadastral Information,’Proceedings of AURISA'92 - 20th International Conference of AURISA. Gold Coast, Australia pp.238-249. 125 ANZLIC, 1996, Spatial Data Infrastructure for Australia and New Zealand- Discussion Paper, Australian & New Zealand Land Information Council (ANZLIC) spatial information council, available on-line Internet http://www.anzlic.org.au/asdi/anzdiscu.htm (accessed July 2001).
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2.8 Summary
The chapter has examined and described some of the main background aspects
relevant to this thesis study. Cadastral communication has explored the issue of
transmission of property information and draws upon parallels with communication
theory. This foundation places in context the importance of understanding the notion
of best evidence for cadastral reinstatement. This clearly relates to the hypothesis
under considering in this thesis. Further, this section summarises aspects of property
boundary evidence before the investigation of central concepts detailed in later
chapters.
The review of accuracy requirements associated with property surveys demonstrated
non-uniformity of prescription across the jurisdictions in Australia. This review
provided background impressions to the varying accuracy descriptions and provided
some basis to establishing the idea of adopting position-based property information.
Related to this position-based argument has been discussion on the provocative issue
of coordinate based descriptions and limitations in the context of suitable
measurement representations. This aspect is of importance in considering the
adoption of metric information derived from a global measurement system to
describe property locations in part.
A topic requiring further research is the risk management strategies relating to
cadastral surveying and mapping production functions at an organisational level to
improve the integrity of the cadastre. These strategies also require understanding of
additional systematic redundancy and minimising entropy influences. Holistic risk
management of the land administration activities in the State of Queensland would
be a worthwhile institutional undertaking to identify if appropriate resources and
sub-systems are operating effectively.
The impact of geographic information systems has been a driving force for users of
spatial data in Queensland to demand highly accurate information for a multitude of
applications. Within this user-demand context, the following chapters propose an
improved way of organising survey information that can benefit a wide-range of
users while minimising the waste of electronic measurement information.
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CHAPTER THREE
CONCEPTS OF MEASUREMENT-BASED
SPATIAL INFORMATION SYSTEM FOR A
FUTURE QUEENSLAND CADASTRE
The universe cannot be read until we have learnt the language and become familiar
with the characters in which it is written. It is written in mathematical language, and the letters are triangles, circles and other
geometrical figures, without which means it is humanly impossible to comprehend a
single word.127
3.1 Introduction
The literature often mentions that when implementing a multipurpose cadastral
system the starting point is the establishment of a stable geodetic control
network. This chapter introduces the concepts of a Measurement-Based Spatial
Information System (MBSIS) with the purpose of demonstrating how this
concept would be most useful with GPS and other electronic data collection
technology applied in local controlled cadastral areas. 127 Quotation by Galileo Galilei, Cited in O'Connor J.J, and Robertson E.F., 1995, Biography of Galileo Galilei – Quotation by way of Opere Il Saggiatore p. 171, Published by School of Mathematics and Statistics University of St Andrews, Scotland. Available on-line Internet http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Galileo.html (accessed Dec 2001)
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The fundamental concepts of measurement based multipurpose cadastre
systems are that measurements are first class objects and the primary
information. Co-ordinate values that are required by answer to structured
inquiries should be completed from the stored measurements when required by
the query. Additionally, how can we have a stable measurement description
when the physical dynamics of the world are changing?
Cook’s (1994) research has asserted that Surveyors jettison a lot of primary
information to produce the derived information typically contained within a
cadastral survey plan in Queensland.128 The majority of Geographic
Information Systems have advanced a common digital reference system by
representing points within raster and vector based databases as two-dimensional
co-ordinates and in more recent times three and four-dimensional co-ordinates.
The fresh approach to the concept can be demonstrated by the following
example. A land area is required to be surveyed and an adequate number of
geodetic control points are required to be establishment before base maps can
be prepared. The Local Authority would require submission and acceptance of
a proposal before proceeding to construction, survey and titling functions.
Further base maps have to be reasonably complete before surveys for parcel
boundaries (new subdivisions) can be undertaken. It is the primary
measurements made in the field, by surveyors, which hold the critical
information useful to a Measurement Based Spatial Information System
(MBSIS). The current approach to cadastral surveys is that the process jettisons
much of the primary measurement information to produce a paper-based
hardcopy survey plan of the status of the cadastre at the time of survey.
The last steps in the implementation of a new multi-purpose cadastral system
are the derived co-ordinates. In each of these steps, (in working from the 128 Of particular interest to this study is chapter 4 - Issues in the Design of a Viable Cadastral Surveying and Mapping Organisation, pp.122-163 of Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis,
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whole to the part philosophy) related field surveying measurements are stored
in the local area database and are processed when needed with the resulting co-
ordinates stored for use in answering the query at hand. Others have examined
the implementation phase of such a concept within a United States county pilot
project region, including benefit/ cost ratios of achieving this change and issues
of on-going management and maintenance. It is acknowledged that further
analysis and research are required to make meaningful comparisons between
the current Queensland land administration system and any proposed
implementation of a MBSIS at a pilot project level or local government area.
3.2 Definitions of Measurement Based Systems
During the last decade, the topic of cadastral reform has been on the agenda of
state, national and at times international surveying related organisations. As this
thesis proposes another model of organisation of spatial information, it should
be worthy to examine the context of a proposed system, management issues and
what constitutes suitable performance metrics of system improvement.
Additionally, the issue of a GPS measurement centric focus influencing a
MBSIS is discussed at relevant sections.
3.2.1 Context of a "System"
In this technology-driven society, the meaning and usage of the word system
has become somewhat nebulous or amorphous. In terms of proposing a
measurement based local controlled cadastral system, an examination of the
generic meaning(s) of system is worthwhile. DiStefano et.al. (1987) provides
useful definitions and explanation in this area. Definition 1.1a: A system is an arrangement, set, or collection of things connected or related in such a manner as to form an entirety or whole. Definition 1.1b: A system is an arrangement of physical components connected or related in such a manner as to form and/or act as an entire unit. The word control is usually taken to mean regulate, direct or command.
Queensland University of Technology. Selected chapters also available on-line Internet http://www.plas.bee.qut.edu.au/www_jsc/jscpubs.htm#dissertation (Nov 2000)
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Definition 1.2: A control system is an arrangement of physical components connected or related in such a manner as to command, direct or regulate itself or another system. 129
In this context, a measurement control system can direct surveyors, as one
group of users, to overall cadastral quality expressed as error ellipses. Ongoing
performance of cadastral quality provides sound feedback information for
assessing current and surrounding survey data.
Conversely, consideration of a cadastral system that is deemed “out of control”
would lead to a large number of boundary related disputes and confusion. This
could further lead to a serious undermining of the government’s guarantee of
title of ownership, rights and restrictions in relation to a described parcel of
land. An “out of control” cadastral system would lead to a situation of
questionable integrity in the cadastre related not only to the community’s low
confidence that all registered owners and interests are correct, but also to their
lack of confidence that the boundaries of all land parcels are reasonable and that
errors are a regular occurrence. A manager’s measure of “out-of-control”
circumstance could be tied to the unacceptable level of boundary disputes in a
region. However, problem survey areas where boundaries appear uncertain in
relation to the constructed improvements are an exception or special
circumstance.
Control systems can be further classified into two general categories; namely
open-loop and closed-loop systems. The distinction is determined by the control action, which is that quantity responsible for activating the system to produce output. Definition 1.5: An open-loop control system is one in which the control action is independent of the output. Definition 1.6: A closed-loop control system is one in which the control action is somehow dependent on the output. …..closed-loop systems are more commonly called feedback control systems. In order to classify a control system as open-loop or closed-loop, the components of the system must be clearly distinguished from components that interact with, but are not part of the system. Feedback is that characteristic of closed-loop systems which distinguishes them from open-loop systems.
129 Di Stefano, J.J., Stubberud, A.R., Williams, I.J., 1987, Theory and Problems of Feedback and Control Systems SI (Metric) edition, International edition, Schaum's Outline Series, McGraw-Hill Book Company. P.1.
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Definition 1.7: Feedback is that property of a closed-loop system which permits the outputs (or some other controlled variable of the system) to be compared with the input to the system (or an input to some other internally situated component or sub-system of the system) so that the appropriate control action may be formed as some function of the output and input.
More generally, feedback is said to exist in a system where a closed loop sequence of cause and effect relations exist between system variables. In essence, every passive system (one containing no energy sources) may be viewed as a feedback system.130
If surveyed measurement information is considered as a monitoring function,
then a system’s approach will require reinforcing of the need for redundancy
and accuracy representations. A management feedback technique may be
achieved via the use of boundary position error ellipses improving over time in
a management area. An issue arises that timely feedback information, in a
comprehensive form within a measuring system, is vital to deduce movements
between measurement epochs and potential consequences of not receiving
feedback information. An additional management alternative to this point can
be via applied learning experiences: The concept of ‘feedback’ originated with cybernetics. Hence the monitoring and evaluation of policies is central to a cybernetic approach to management. In essence it involves a systematic learning by experience as an essential part of the management process. Such learning is entirely compatible with the aims of science, and the best available learning is needed to manage important land management issues in Queensland.131
From a theoretical perspective, a closed-loop system architecture applied to a
measurement-based locally controlled cadastral system would provide, via
suitable measures of performance metrics, characteristic management
improvements to the current system. These improvements include but are not
limited to the following:
• Increased accuracy - measures of cadastral improvement with reducing
average error ellipses for a particular local authority area or region.
130 Ibid., pp3-4. 131 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (May 2002). Conclusions chapter p.356.
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• Decreased boundary conflicts and disputes as the captured measurement
information provides a basis of support and justification of the boundary
or other asset in question.
• Reduced sensitivity to temporal variations in measurement techniques
and instrumentation.
• Field surveyors meeting or exceeding the existing cadastral
management performance indicator (accuracy) by using improved
measurement instrumentation with high precision, thus providing new,
quality data feeding back into the local system.
• Decreasing incidents of information conflicts, which create arguments
between parties including disagreement between surveyors.
Arguably, the emphasis of these improvements is a compromise between
alternative methods thus allowing objects (including digital data) to be
computable to satisfy management objectives and policy directions without the
burden of overly complex and costly optimisation methods. An issue requiring
exploration is whether greater coherence in the dataset will improve the overall
information system. Arguably, measurement information that collaborates
existing information, rather than creating conflicts in a system, will lead to a
system performance enhancement over time. Other issues requiring
consideration include the responsibilities of a land developer for making
changes to the digital cadastre and take increased responsibility for boundary
mapping and local authority impacts. Conceivably this could be applied in
much the same way as water and sewerage head-works infrastructure charging
occurs.
3.2.2 Management Control and Performance
A viewpoint about management control is that it is the process through which
managers assure that actual activities conform to planned activities.132 Stoner
(1994) supports this viewpoint in that describing business activity and the
functions of a manager such that controlling via management means monitoring
132 Stoner J., Collins R., and Yetton P., 1985, Management in Australia, published by Prentice-Hall of Australia, p.726.
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the plans to ensure that they are being carried out properly.133 The essential
elements of a control process are encapsulated in the following statement: Management control is a systematic effort to set performance standards with planning objectives, to design information feedback systems, to compare actual performance with these predetermined standards, to determine whether there are any deviations and to measure their significance, and to take any action required to assure that all corporate resources are being used in the most effective and efficient way possible in achieving corporate objectives.134
Stoner et.al. (1985) argue that this can be segmented to four steps in the
management control process. This point is worthy of consideration in terms of
management of cadastral and measurement systems that may meet the
objectives of F.I.G.’s Cadastre 2014 vision while also remaining sufficient of
government policy and resource expectations. The following is a traditional
approach:- The first step is to establish standards and methods for measuring performance. For this step to be effective, the standards must be specified in meaningful terms and accepted by the individuals involved. The methods of measurement should also be accepted as accurate. An organization may set an objective to become the “leader in its field”, but this standard is little more than verbal inspiration if it is not defined and if a system of measurement is not established. The second step is to measure the performance. Like all aspects of control, this is an ongoing, repetitive process, with the actual frequency dependent on the type of activity being measured. … A fault to be avoided, however, is to allow too long a period of time to pass between performance measurements. Does performance match the standard? In many ways, this is the easiest step in the control process. The complexities presumably have been solved in the first two steps; now it is a matter of comparing measured results with the target or standard previously set. If performance matches standards, managers may assume that “everything is under control”. The final step is to take corrective action if performance falls short of standards and the analysis indicates action is required. This corrective action may involve a change in one or more activities of the organizations operations, or it may involve a change in the standard originally established.135
Stoner et.al. (1985) additionally note that managers need to exercise control of
both financial and non-financial elements to carry out their activities
133Supported by comments made by Stoner J., 1994, Management, published by Prentice-Hall of Australia, p.36. 134 Hirohide Hinomoto, 1975, ‘Education in Information Systems’, Academy of Management Journal, 18,no.2, p.402-407. (Cited by James Stoner, 1985, p.726) 135 Stoner J., Collins R., and Yetton P., 1985, Management in Australia, published by Prentice-Hall of Australia, p.727-728.
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successfully. Unless managers see the control process through to its conclusion,
they are merely monitoring performance rather than exercising control.136
Cook (1994) contributes to the debate when discussing a cybernetic approach
through a viable system model applied to modeling Queensland’s cadastral
surveying and mapping system. The general implications for management
information systems operating within this model can be summarized thus: Highly developed surveying and mapping systems, statutory valuation systems, and regional information systems require an ability to: * undergo regular revision and updating without losing its historical content * allow simultaneous centralisation and decentralisation of information * maintain high levels of accuracy, integrity and reliability of information * isolate faulty information sources out of the many sources that contribute routinely to cumulative stores of information. These factors apply to sophisticated spatial organisation generally. The lessons learned from routine land information processes, and the ability to describe and interpret dynamic land usage, are likely to find wider application in management and government. Description or modelling of a system is an essential ingredient in its proper management, and the Viable System Model provides a systematic and economical aid to the description process.137
According to Stoner et.al.(1985), effective and reliable control systems appear
to share certain characteristics in common. These characteristics can be
demonstrated through an example of a small survey practice.
A small workforce normally manages a multitude of functions to achieve a
common goal - to get the work or survey information to the client in an
effective manner. The experienced worker maintains knowledge of the logical
processes involved whilst maintaining flexibility of the circumstances that
avail. The manager, or person responsible for supervising, manages the
operations of the project without micromanaging the detail.
Many survey practices have instigated quality management principles into the
process. Part of those principles include quality assurance of the final product
136 Ibid., p.728. 137 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (May 2002). Conclusions chapter p.354-355.
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(survey and mapping information) complimenting the larger risk management
operations of an organisation. Risk management associated with the operational
reality of an organisation requires flexibility and some standardization of
procedures adapted to survey practice workflows.138
Additionally of interest for a proposed MBSIS operation, ability is required to
identify and validate individual measurements with larger residuals after an
adjustment stage. This ability also requires provision of corrective management
action through re-measurement of the subject data.139 Review of literature on the process of management found that the
controlling function of management involving three distinct elements:
• Establishing standards of performance140
• Measuring current performance and comparing this
performance against established standards or benchmarks.141
• Taking action to correct any performance that does not meet
suitable levels or standards.142
Management performance is as much about what activity is measured
and monitored as to the specific performance improvement or decline.
Performance measures of effectiveness rely on a sound understanding
of the functions and organisation of the activity in question.143 These
effectiveness trends indicating improvement (or decline) of the 138 Price P.M. 1991, Management for Surveyors: Facts, Theories and Notions, pp.2-44, Association of Consulting Surveyors Qld – Management for Surveyors Seminar. 139 A graphical example of this capacity to identify larger residuals requiring re-measurement corrective action is presented at section 3.3.8. 140With reference to the Specific; Measurable; Agreed; Realistic; Timeframed –(SMART) model developed by HRINZ which appears to offer some suitability to surveying environment, HRINZ, 2002, Guide to Performance Management, Human Resource Institute of New Zealand, available online Internet http://www.hrinz.org.nz/info/guides/performance_management.asp (accessed Dec. 2002) 141 Comparsions are made to FIG initiative in benchmarking cadastral and land administration systems - FIG, 2002, Benchmarking Cadastral Systems. F.I.G. Commission 7- Cadastre and Land Management, working group 1998-2002 – reforming the cadastre, compiled and edited by Stendler, D. and Kaufmann, J. April 2002. Available online Internet http://www.swisstopo.ch/fig-wg71/benchmarking.htm (accessed Nov. 2002) 142 For example performance tuning to improve outcomes as discussed by four case studies outlined by Michael Augello, 1999, A Corporate-wide Approach to Capacity and Performance Tuning, Deakin Management Consulting including CPT Global, Melbourne. Variable pp. Available online Internet http://www.cptglobal.com/report.htm (accessed Dec. 2002)
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strategic goals should focus not only on the processes involved but
also on the outcomes achieved.
Cook (1994) has previous investigated management models of complex
organisations and specifically Beer’s viable system model. Beer’s Viable System Model provides a systematic and economical method of describing a wide variety of complex organisations. It is, above all else, a conceptual model of an organisation’s management information system; a map of how an organisation processes information to manage its affairs and remain in business.144
There are a number of documented users of this model that are often utilized in
conjunction with other strategic planning techniques. Cook’s (1994) literature
review of the application of this system model approach found: There are a number of published papers which indicate use of the model in diagnosis of organisational deficiencies in the trade training network in New Zealand,145 the United States Air Force Logistics Command,146 and organisational issues in the Greek railway system.147 A recent anthology reviewed applications in an electrical engineering company,148 a commercial broadcasting enterprise,149 the Mount Sinai School of Medicine (which operates as an academic medical center),150 a United Nations funded review of government information systems in Uruguay,151 and a non-human system comprising organisation of honey production by bee colonies.152
143 Cullen R., 1999, ‘Does performance measurement improve organisational effectiveness? A postmodern analysis’, Performance Measurement and Metrics Journal, pp. 9-30, Vol.1, No.1, August 1999. ASLIB. Association for Information Management. Page 13. 144 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Chapter 3 Introduction pages 88-89. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (accessed Nov. 2002). 145 Britton G.A. and McCallion H., 1985, ‘A case study demonstrating use of Beer’s cybernetic model of viable systems’, Cybernetics and Systems: an International Journal, Vol.16 Nos.2-3 pp.229-256 (by way of J.S.Cook-1994) 146 Tripp Robert S., and Rainey Larry B., 1986, ‘Design of a control room for the Air Force Logistics Command (AFLC): Command, Control, and Communication and Intelligence (CT)’, Cybernetics and System: an International Journal, Vol.17 Nos.2-3, pp.211-235. (by way of J.S.Cook-1994) 147 Paradissopoulos Iordanis K., 1990, ‘An assessment of the management of a railway enterprise from a management cybernetics point of view’, Cybernetics and System: an International Journal, Vol.22 No.2, pp.173-195. Paradissopoulos Iordanis K., 1991, Diagnosing problems in the structuring of operational activities in a railway enterprise in terms of Beer’s model of Viable Systems’, Cybernetics and System: an International Journal, Vol.22 No.1, pp.57-88. Paradissopoulos Iordanis K., 1992, Cybernetic model of the railway enterprise’, Cybernetics and System: an International Journal, Vol.23 No.1, pp.67-104. (by way of J.S.Cook – 1994) 148 Espejo R., 1989, ‘P.M. Manufacturers: the VSM as a diagnostic tool’, The Viable System Model: interpretations and applications of Stafford Beer’s VSM, ed. By Raul Espejo and Roger Harnden (Chichester:Wiley, 1989) pp.103-120. (by way of J.S.Cook –1994) 149 Leonard A., 1989, ‘Application of the VSM to commercial broadcasting in the United States’, ibid, pp.175-209.(by way of J.S.Cook –1994) 150 Ben-Eli Michael U., 1989, ‘Strategic planning and management reorganisation at an academic medical center:use of the VSM in guiding diagnosis and design’, The Viable System Model: interpretations and applications of Stafford Beer’s VSM, ed. By Raul Espejo and Roger Harnden (Chichester:Wiley, 1989), pp.299-329. .(by way of J.S.Cook –1994) 151 Beer Stafford, 1989, ‘National government: disseminated regulation in real time, or “How to run a country”’, The Viable System Model: interpretations and applications of Stafford Beer’s VSM, ed. By Raul Espejo and Roger Harnden (Chichester:Wiley, 1989), pp.333-360. (by way of J.S.Cook –1994) 152 Foss R.A., 1989, ‘The organistaion of a fortress factory’, The Viable System Model: interpretations and applications of Stafford Beer’s VSM, ed. By Raul Espejo and Roger Harnden (Chichester:Wiley, 1989), pp.121-141. (by way of J.S.Cook –1994)
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Cook (1994) has examined in detail the application of the viable system model
in analysis of surveying and mapping organisation for Queensland.153 His
findings noted that for land management application of structural
reorganization, the model has many positive points including that the approach
is systematic in that the hierarchy is desirable as a coordination approach to
complex organizations and production functions. Also noted was that the
approach was also able to identify particular organizational weaknesses. The
viable system model provides a basis for successful re-organisation, which can
cope adequately with preserving rather than suppressing separate identities.154
3.2.3 Measures of System Improvements
In the context of Information Technology, supposed knowledge that a system is
improving is not enough in today's management approach. The need to quantify
and justify improvements with evidence or other key indicators (performance
metrics) is usually required. Managers of a system in a large private or
government organisation often require performance indicators of a particular
element or sub-set of a system. Cook’s 1993 paper adequately describes the
accountability regimes associated with cadastral surveying and mapping
operations in Queensland.
The detailed description of systems involved in production needs to be followed by proper analysis of: • What is the purpose of each operation. • What criteria can be used to say that it is being done successfully. • Is there a useful statistical indicator which can be used to measure success.
153Of specific study is Part A – Chapters 2 and 3 which looks at Beers Viable System model and its application with strategic management of Qld land administration functions. Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (Accessed May 2002). 154 Ibid., p119-120.
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• Can these performance statistics [indicators] be generated without undue cost in terms of the financial resources and human relationships involved.
• What mechanisms exist for correcting production performance which is not meeting expectations (implying that performance, expectations or both may need to be modified if management is to be in touch with production realities).155
When proposing a new model of organisation for cadastral and other
survey information within a local controlled area based on defined
bounds, the measures of success become more important as the
modelling of the underlining geodetic network is presumed fixed. It is
the propagation of errors from an assumed fixed origin to the working
measurements associated with the cadastral survey that would serve as a
key indicator of improvement.
A section of Cook’s (1993) table on operational accountability regime, as part
of a viable cadastral surveying and mapping model, is included to set the
context of useful statistical indicators for a MBSIS operating within a local
controlled area. Measures of a systems performance are suggested by Cook’s
(1993) indicative criteria for success and the statistical indicators of the criteria
in question.
155 Cook, J.S., 1993, Problems of Geodetic Organisation and its Linkages with Cadastral Organisation, Proceedings of 1993 Winter School - Asset Management in Local Authorities. School of Surveying, Queensland University of Technology. Page 19 of 28 pages.
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This Table/Diagram is unavailable online. Please consult the hardcopy thesis
available at the QUT Library
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This Table/Diagram is unavailable online. Please consult the hardcopy thesis
available at the QUT Library
Table 3.1: Cook’s (1993) accountability regimes for cadastral control and cadastral surveying. Part of Cook’s research work suggesting key statistical indicators of success for cadastral surveying and mapping; and other sub-systems.156
The criteria for success and statistical indicators of success, as outlined in the
table above, are extremely useful as measures of a system’s improvement and
monitoring of an organisation’s performance. From a geodetic perspective,
spatial scientists are now starting to gain an increased understanding of the
geodynamics of the Australian mainland and its territories. Rather than
examining the absolute accuracies of control points within a local controlled
area, it is perhaps of more importance to look at long time-series of relative
positioning data with respect to the AFN and how the precision associated with
this relative positioning is improving over time.
This analogy need apply at the local controlled area level whereby the precision
of positions associated with each monitored control point within a local
controlled area is improving with time (with highly developed measurement
and data analysis techniques). Of equal importance is the relative accuracy to
the one or two monitored control points with an LCA to an adjoining LCA to
detect potential geo-movements between regions. Improved knowledge in this
topic is starting to be realised with the AUSLIG production of time series 156 Ibid., p20. Also contained in PHD dissertation – Issues in the design of a viable cadastral surveying and mapping organisation, chapter 4 pp.147-148. Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D.
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graphs for continental scale movements detected and the associated
improvement in standard errors.157 Other countries are implementing
continuously monitoring networks similar in operation to the Australian
Regional GPS Network (ARGN);158 the North American Continuously
Operating Reference Station (CORS) program;159 and the Southern California
Integrated GPS Network (SCIGN).160
Issues of system design and data management for regional land information
systems are placed in context, thus: Attempts at constructing computerised land information are placing pressure on geodetic and control surveying systems. Cybernetic modeling identifies data management as a major problem in providing control in cadastral and engineering surveys. The problems of managing this data are continually underestimated, partly because surveyors do not necessarily possess the necessary skills in records management. Surveyors complain about shortage of resources to perform control survey operations. At the same time they jettison valuable information after it is obtained. This loss of information occurs through an inability to maintain an adequate record.161
With this context in mind, the concept of a measurement based cadastral system
is introduced.
Thesis, Queensland University of Technology. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (Accessed Dec. 2002). 157 For example, see graphs contained in figure 4.7 coordinate time series graph 1998 to 2002. 158 Further information on time series graphs relating to ARGN quality can be found on-line Internet http://www.auslig.gov.au/geodesy/argn/argnqual.htm (accessed December, 2000) 159 Further information on the CORS program is available on-line Internet http://www.ngs.noaa.gov/CORS/ (accessed December, 2000) 160 Further details and graphical trends of detected movements by SCIGN can be accessed online Internet http://scign.jpl.nasa.gov (accessed Jan. 2003) 161 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis, Queensland University of Technology. Selected chapters also available on-line Internet http://www.dbe.bee.qut.edu.au/people/cookjs/jscpubs.htm#dissertation (May 2002). Conclusions chapter p.350.
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3.3 Concept of a Measurement Based Cadastral System
The fundamental concepts of a measurement based multipurpose cadastral
system are that measurements are first class objects and that those
measurements are the basic carriers of metric information. Updating a database
of a measurement-based system with new measurement information only
requires the addition of measurements to the data-base. Through a standard data
collection format, users could potentially supply their original information to
the MBSIS by way of digital lodgement avenues.
Digital lodgement should not be dealt with in isolation, but rather should form an integral component of a digital survey environment. The main objective of introducing digital lodgement is to contribute to a complete digital environment to efficiently manage and utilise land-related data.162
This digital measurement-based approach adds a great deal of automation to the
data collection and submission process and would require a high level of
quality assurance and professionalism to be applied by the practising surveyor.
Re-computation of measurements is not overly imperative in an MBSIS and
could be deferred until needed by queries. The metric information is always up-
to-date because the latest measurements have been integrated into the database
and are readily available for processing.
Buyong (1992) carries this argument forward with the following important
consideration: ……. With the wide-ranging functionality of present multipurpose cadastral systems, stored coordinates that are updated rarely can no longer satisfy some users groups, especially those that demand more up-to-date information. The main reason for not updating stored coordinates regularly is the tedious process of integrating new measurements with coordinates computed from earlier measurements that are not stored in the system. Measurement-based systems provide a solution by suspending the processing of measurements until such time when coordinates values are needed. By deferring the adjustment process, all relevant measurements can be included.
162 Falzon K., and Williamson I., 2001, Digital Lodgement of Cadastral Survey Data in Australia – User Needs, Trans Tasman Surveyor Journal, No. 4, p.9.
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The demand for fast response and a possibly high frequency of queries, however, make it impractical to adjust the entire network of measurements in a database whenever coordinates of some points are required, Fortunately, only measurements that are in the vicinity of the desired query area need to be considered. Distant measurements do not influence the coordinate values of points in the desired area significantly and can be neglected.163
Co-ordinate values that are required to structure inquiries should be completed
from the stored measurements when required by the query. Studies such as
those by Elfick (1995) and Durgin (1993) support the notion that the
implementation of a measurement-based system requires measurements to be
stored in the database such that they become accessible for future use.164 These
would include measurements made between higher quality points (primary
local area control), measurements relating to the parcel boundaries themselves,
and measurements made to other objects of interest such as fencing, utility
assets, roadway assets etc.
While one of the foci of a measurement-based information system is of the
measurements themselves (the base data) being stored, it is beyond the normal
descriptions of a strictly object-oriented management software approach.165 The
fundamental principle of the object-oriented approach is the concentration on
data and the interfaces to that data. However, a measurement-based information
system falls outside this approach as discussed in part by the following notions.
163 Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine. Chapter 2 p17. 164 Elfick, M.H., 1995, A Cadastral Geometry Management System, The Australian Surveyor, Vol. 40, No.1, pp35-40.; Durgin, P.M., 1993, Measurement-Based Databases: One Approach to the Integration of Survey and GIS Cadastral Data. Surveying and Land Information Systems, Vol.53,No.1, 1993,pp.41-47. 165 An object-oriented approach for Qld Geodetic management is discussed in detail by Stoodley, M., 1997, 'Object Oriented Approach to Geodetic Adjustments and Calculations', The Queensland Surveyor, June '97 edition, pp.46-53.
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3.3.1 Notions of a Measurement Based Spatial Information System
While the concept of measurement-based multipurpose cadastral systems is not
overly new, Buyong (1992) describes the foundation elements of the approach
in a comprehensive manner.166 The following notions are some of the major
issues first described by his research when a trial implementation of the
measurement based information system was considered as a pilot project for
Penobscot County, in the state of Maine, United States. This county has a
population of about 150,000 and a land area of about 8300 square kilometres
divided into approximately 40,000 parcels.167
Major issues are explored and summarised whilst placed in context for a
Queensland land management environment:
• Measurements are first class objects
• Storage of measurements
• Processing of measurements
• Local adjustment of measurements
• Updates and maintenance of measurement databases
• Storage of co-ordinates for efficiency reason
• Gradual data collection
• Increase in accuracy over time
• Change in co-ordinate and derived metric values
• Data Quality assessment
• Differentiation between legal and non-legal metric values
• Digitised photogrammetric co-ordinates and ambulatory boundaries.
These notions are a precursor to exploring the issues of MBSIS information
integration for a wide range of tangible and non-tangible benefits including the
arguable need to improve management of the state surveying and cadastral
infrastructure into the electronic database future.
166 Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine. Chapter 2 p26. 167 Ibid., p. 131.
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3.3.2 Measurements are First Class Objects
A MBSIS uses the measurements themselves to provide metric information.
The measurements are processed to obtain the relevant point co-ordinates,
which are then in turn used for the determination of the required metric
information. Buyong (1992) provides a succinct example of this, such that:
If a query about the road frontage of a parcel is posed, the information is obtained by processing the measurements of the boundary line and other related measurement data to obtain the coordinates of the two end points of the boundary lines. The computed coordinates are then used to calculate the length of the boundary line.168
Figure 3.1: Processing of boundary measurements. The road frontage of parcel P is obtained by processing the boundary measurements of parcels P,Q,R and S.169
This approach is markedly different from a coordinate-based system where the
length information is obtained from differencing of the pre-computed co-
ordinate values of the two end-points representing boundary corners.
168 Ibid., p.26 169 Ibid., p.27
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3.3.3 Storage of Measurements
As the name implies, an MBSIS requires the measurements to be stored in the
system’s database so that they are easily accessible. These measurements
include those between: geodetic control points; traverse measurements between
stable monumentation, that is cadastral pins; measurements related to parcel
boundary that is radiations to original peg or fence-post; and measurements of
other objects of interest.
The important distinction relating to the term "measurement" means foundation
measurements that are typically available from surveying instruments. The
measurements have been corrected for systematic effects involving instrument
and atmospheric conditions. In the specific case of GPS, the foundation data
files or suitable Receiver Independent Exchange (RINEX) data format may be
suitable if data standards and protocols provided consistent and uniform data. It
is proposed that raw carrier phase and pseudorange GPS data is not stored in
the database, but rather a four dimensional vector representation that covers the
DGPS techniques commonly used. A MBSIS would not contain GPS
observation processing software for re-processing of raw satellite observation
data. In certain cases, the storage of RINEX data would be useful in providing
an independent re-computation of some linkages by an external software
processing provider. For example, the linkage from known higher order survey
control to the Australian Fiducial Network (AFN). This is somewhat similar in
concept to the AUSPOS and IGS regional processing approach.
Buyong (1992) describes at great length the class of objects and their attributes
to be contained in his vision of a measurement-based multipurpose cadastral
system.170 Whilst the clarity of description of his original work appears
confused, a new schema diagram based on his interpretation is presented in
Figure 3.2 for clarity.
170 Ibid., p.68-75.
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Figure 3.2 : Entity-Relationship Schema for linkages between elements.171
171 Partially based on the schema diagram by Taher Buyong, 1992, Ibid., p.74. Heavily modified, manipulated and enhanced based on Pittsworth QLD Database design by Robert Webb, and further development to be inclusive of GPS measurement observation summary 2001 for cadastral information organisation..
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The entity-relationship schema has been heavily modified and manipulated to
improve explicitness aspects of the linkages and a consistent shape diagram
applied to the like-groupings. For example, the use of circles at the lower end
containing raw values and associated variances. Also, the use of rectangular
boxes for the description with the linkages contained within a diamond shape.
The distinction of measurement elements can be seen by the logical groupings
of attributes.
While Buyong’s (1992) work does not provide detail on source measurements,
for a Queensland environment it is proposed that the stored measurements can
be further categorised according to their source for the purpose of aiding in
distinguishing acceptable precision criteria of the source material. In the first
category are measurements usually used in terrestrial positioning tasks such as
angles, distances, directions, bearings and azimuths.
The second category would contain measurements from other positioning
systems such as GPS vectors and high-precision photogrammetric co-ordinates.
Of special note are the GPS derived vectors, which should be assigned a further
attribute of data-collection technique, for example, Real-Time Kinematic
(RTK) vectors, Fast-Static derived Vectors (FSV) or Virtual Reference Station
(VRS) positions. As GPS measurement techniques mature, a larger number of
cadastral surveys will presumably be performed by these techniques due to the
inherit time efficient nature. Theses include aspects of measurement
redundancy, improved automation of office processing and the often one-person
field operator required for data collection purposes.
The third category of measurements is digitised and photogrammetric co-
ordinates, which are generally the cheapest type of measurement to acquire and
hence have a lower quality assignment due to the inherent lack of ability to
propagate information to other points. This category of measurement is
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arguably considered as a single measurement only, given the nature of the data
collection techniques. Ambulatory boundaries fall into this category of
measurements because they are only considered reliable at the time of survey,
and are often considered as singular measurements collected operationally as
offset information. Photogrammetric methods are very useful for engineering
purposes and asset management applications but can rarely provide a consistent
precision.172 Photogrammetric surveys are more suitable for long-line surveys
or where broad coverage is required. For example, surveys associated with a
native title boundary between natural boundaries, be it a creek, ridgeline,
swamp areas, edge of forest, edge of sand-dunes.
3.3.4 Processing of Measurements
A key innovation of a MBSIS is that the system defers the processing of
measurements. The measurements are processed at a time when a piece of
information is needed to answer a particular query. For surveyors about to
undertake a property survey, an adjustment would be undertaken prior to
fieldwork to ensure the most up-to-date measurements are included in their pre-
analysis stage of a project. The storage of resulting point co-ordinates from the
measurement processing operation is not overly important as they can be re-
calculated if they are needed by other queries. This approach of processing
information only when a query is instigated will make best use of new and
improved accurate measurements information as and when it becomes
available.
Harris (1996) contributes to the issue of importance of measurements prior to
processing and standardisation with traceability linkage, thus: A cadastral reinstatement could be described as comparison of new measurements (a homogeneous set?) with original measurements (usually an inhomogeneous set?), the link between the measurements being the available evidence (e.g. plans, field notes, occupation, monuments etc). The weight associated with each piece of evidence influences the
172 Slama, C, 1980, Manual of Photogrammetry. Published by American Society of Photogrammetry, Falls Church Va, 4th Edition. P413.
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reinstatement outcome and the application and knowledge of considerable judgement (traceable?) may be necessary. A difficulty arises with this comparison because the measurements being compared may not have been determined directly and indirectly determined measurements will always require checking. Whether the measurements have been checked or not may be unknown (with the least squares approach all measurements are used).
• When unchecked indirect measurements agree with original, what does this establish?
• When unchecked indirect measurements disagree with original, what does this establish?
• The same questions for checked indirect measurements? • The same for checked and traceable measurements? • The areal extent of a cadastral reinstatement needs to be
sufficient to establish the intent of the original survey(s), this may also include scale variations?
• If scale variations between surveys are allowed then why is traceability of length required?
Given that one of the principles of cadastral reinstatement is to try to limit variations from original ‘deed’ measurements, the precision of the measurements in the cadastre will only improve with new subdivision, is the existing precision sufficient anyway? It may be decades between visits to a cadastral parcel for reinstatement purposes (and the possibility to improve precision).173
To produce the best estimate of point co-ordinates for a query, the method of
least squares is used to process the measurements because it considers all
measurements contributing towards a solution.174 This method allows all
categories of measurements, each category with variable accuracy associated to
the measurements, to be processed in an integrated manner. Other methods of
adjustment normally limit the consideration to a number of nearby
observations. The method of least squares is most useful as it considers all
measurements contributing to a solution and allows a weighting to certain input
data. Buyong (1992) discusses at great length the purpose of redundancy to
assess the accuracy and reliability of the processed co-ordinates using the
method of least squares adjustment containing the functional and stochastic
173 Harris M.W., 1996, ‘On the Traceability of Measurements’, Proceedings of Seminar'96- Re-Instatement: Principles and Practice. Association of Consulting Surveyors, Queensland. 174, Trimble Navigation Ltd, 1992, TRIMNET Plus Survey Network Software User's Manual, Survey & Mapping Division, published by Trimble Navigation, Sunnyvale, California. Background materials associated with least squares applied to GPS source data can be found chapter 8, 'The Surveyors Practical Guide to Least Squares'.
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relationships.175 This topic, while a distinguishing feature and most-often
applied in GPS control networks, is beyond the theoretical scope of this thesis
given the weighting strategies employed in the adjustment.
However, a holistic approach to a trial MBSIS would need to provide a
weighing strategy to relative measurements as part of the recalculation process.
Harris (1996) has already alluded to this weighting of measurements from
cadastral observations and the evidence used in reinstatement strategies.
Idealistically, this could be applied given a number of measurements of various
ages and various observation techniques and the judgement factor to include or
preclude foundation measurements. For a realistic implementation trial, this
measurement weighting issue requires technical solutions and further
consideration. At the theoretical level, this is identified as a weakness of any
proposed MBSIS that is governed by so-called rules of weighting
measurements.
3.3.5 Local Adjustment of Measurements
The total number of measurements in a systems database may be in the order of
millions. As such, it is impractical to adjust all measurements in such a database
whenever the co-ordinate values of a few points are needed. From some earlier
mathematical investigations by Buyong and Kuhn (1992), they conclude: For most cadastral purposes, it is unnecessary to adjust all measurements in a database if only the coordinate values of some local points are desired. To obtain the adjusted coordinates of a group of points, only measurements around the vicinity of the points need to be included in the adjustment. This can be explained from the perspective that of the theory of geodetic information propagation. An error in a measurement between two points prevents the total flow of coordinate information from one point to the other, such that a series of interconnected measurements may have filtered out the transmitted information significantly. Thus, it is possible to consider only the neighbo[u]ring measurements in local adjustments.
Judging from the experiments conducted on areal networks, chained polygons, traverses, and traverses with side shots [radiations], it is sufficient to include measurements up to four or five steps away from a group of queried points. This is assuming that the standard deviations of the measurements are homogeneous and that points with known coordinate values are available within the group of interested points. The inclusion of more distant
175 Some additional discussion on adjustment of hierarchical control networks. Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine. p101-105.
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measurements does not significantly improve the quality of the points as assessed by relative positions, relative accuracy, and reliability.176
This situation assumes that a reasonable number of stable and recent
monuments maintain a rigid spatial connection. This is rarely the case in rural
cadastral areas. Foundation survey data is required to follow in the footsteps of
the original surveyor. One of these requirements is to fix a datum to gain
agreement with the original surveyed measurements, normally between two,
three or more solid monuments. It can often be decades apart between
measurement epochs. However, this local adjustment approach of
measurements has increased merit in survey areas of recent survey activity and
small time-frames between measurement epochs, such that the adjustment
considers all the measurements contributing towards the solution. This point
would best be operationally realised in regions such as traditional residential
and rural residential developments where surveying activity occurs more
frequently.
A role of cadastral surveyors is to gather evidence, express professional
opinions, and provide facts regarding location of parcel boundaries and the
associated uncertainty measures. The human brain is good at acquiring and
judging each piece of boundary information. However, humans have limitations
when several pieces of information are considered simultaneously. Analysis of
this simultaneous information for the determination of boundary positions can
be obtained by least squares adjustment techniques. The boundary information
that is assembled in a system as measurement data is adjusted to arrive at a
statistically optimal solution. In essence, the spatial information provided by
surveyors of the adjusted parcel boundaries are the product of human
intelligence and the practical scientific techniques of adjustment.
176 Buyong,T.B., and Kuhn, W., 1992, 'Local Adjustment for Measurement-Based Multipurpose Cadastral Systems', Surveying and Land Information Systems, Vol.52,No.1,1992,p.31.
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3.3.6 Maintenance Updates of Measurement Databases
Updating of the measurement-based database needs to consider the integration
of new measurements and omit from consideration old or erroneous
measurements. This integration of new measurements (presumably at a higher
precision in rural surveys in western Queensland) would only require the
addition of the measurements to the database. Buyong’s (1992) model discusses
pre-processing strategies relating to this step for the elimination of systematic
errors and detection of blunders.
Al-Taha (1992) conducted research into temporal reasoning of cadastral
information and provides justifiable support to the notion of maintenance of
measurement databases and discusses Buyong (1992) work in that:
… measurements that are no longer to be used in [the] future, such as those that are suspected to contain errors, are marked "not to be used". They are not deleted from the database because - legal parcel measurements are legal records, - parcel measurements (legal and non-legal) are costly to obtain, and - they may be required again at a later date, for example historical studies.177
In consideration of maintenance programs from a measurement processing
point of view, a MBSIS must satisfy two requirements. The first requirement is
that this proposed system should process:
……all measurements periodically in order to have a reliable copy of coordinate values. This can be realized in several ways: (1) to make the system process measurements at preset time intervals, such as at midnight when most computers are idle, or (2) to make the system process measurements after a certain number of measurements changes have occurred. The new set of computed coordinate values replace existing values. 178
The second requirement is that this proposed system should operationally
process:
177 Al-Taha, K., 1992, Temporal Reasoning in Cadastral Systems, Ph.D. Thesis, Department of Surveying Engineering, University of Maine. P.32. 178 Buyong,T.B., and Kuhn, W., 1992, 'Local Adjustment for Measurement-Based Multipurpose Cadastral Systems', Surveying and Land Information Systems, Vol.52,No.1,1992,p.26.
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… related measurements to answer metric queries for tasks that require up-to-date information on demand. Current computer technology does not allow all measurements in the system, which may be in the order of several thousands to hundreds of thousands, to be processed simultaneously and still maintain a reasonable response time. The strategy is to process measurements in the vicinity of a query area only; this idea is known as localized adjustment.179
It appears somewhat odd that Buyong’s (1992) thesis does not discuss these
computer technology and computing system requirements, yet his earlier co-
authored work has reasoned and discussed this very issue. With rapid advances
in computer technology in the last decade, it may well be worth challenging the
1992 suggestion of slow computing power for reprocessing of all
measurements. Given the more than exponential explosion of GIS technology
linked to computer processing power, speed and memory aspects, it is now
(2003) worthy to consider the processing of tens or hundreds of millions of
observations at the desktop level of computing.
This point has strong merit particularly if constrained to a local controlled area
based on an administrative region such as a local authority area populated with
plentiful geodetic-style control, for example the 10km urban network and
25km-50km rural geodetic networks.
3.3.7 Storage of Co-ordinates for Efficiency Reasons
Buyong (1992) suggests that a measurement-based system may store and use
co-ordinate values that are previously computed from the stored measurements.
This co-ordinate information may, however, be considered as redundant
because it can be compiled at any time, but is useful to gain efficiency, such as
in graphical representations and spatial database access. The real argument is
whether it is better to recompute each time or to store the recomputed data –
each argument has its own inherit costs. Limitations on co-ordinate descriptions
alone have been previous discussed in section 2.6 of this dissertation.
179 Ibid., p.26.
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However, the storage of three-dimensional positions and time using co-
ordinates provides large efficiency in Geographic Information Systems
software. It should be clarified that the co-ordinates are only a representation of
the phenomena in question at a particular point in time. Raw surveying
measurements in the digital form from total stations or GPS instruments,
instead of processed co-ordinate information, are stored in a database of a
multipurpose system and form the basis of metric spatial information.
Co-ordinate values are still the most convenient and easiest to conceptualise.
This point is particularly relevant on engineering projects where a translation of
metric information (based on the common decimal system) is expressed in co-
ordinate X,Y,and Z information. Heavy-engineering manufacturing machinery
all adopt this co-ordinate measurement approach using digital encoded
technology. The ability to describe a three-dimensional position in space
relative to some locally defined datum is conveniently achieved using co-
ordinate communication rather than raw measurement information.
3.3.8 Gradual Data Collection
A MBSIS could be built gradually and solely using measurements that come
from standard daily operations of surveyors such as subdivisions and
identification surveys. This would be on the proviso that a standard data-
recording format is agreed and adopted for data capture depending on the
source. The MBSIS could be started in a small local subdivision, for example,
even though no control points are available. The relative position of points
within a single neighbourhood will not change even if the computed co-
ordinates change.
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A functional support mechanism required of the system is the ability to isolate
individual measurements with larger residuals deemed unacceptable to
management criteria, for example, rural boundary error ellipses higher than 0.5
metres in a local area. Clearly, once a residual problem is identified as not
satisfying the management performance target, the solution would require a
detailed re-measurement to improve the solution and reduce the error ellipse to
acceptable levels. This logical approach can be seen as providing an
improvement in system performance metrics (accuracy) as time progresses.
It is proposed that new geodetic surveys linked to local GPS position
monitoring stations (absolute position referenced to a nationally adopted
framework) and surveys conducted within a LCA gradually provide additive
metric information. This may take several years to capture measurement-based
information for a complete LCA. However, the issue of digital lodgement of
measurements would not be a time-consuming process if incorporated as a
supplementary feature to digital lodgement avenues for cadastral plans. This
would require data standards consistent across the state jurisdiction (including
marine cadastres) and, with federal direction and guidance, extension of the
same standards across other states of Australia.
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Figure 3.3: Graphic representation of cadastral error ellipses after adjustment, sample Linthorpe Valley DCDB. The error ellipse scale is 1:100 of the DCDB data. Communication of this residual data in a graphical format allows problem areas to be quickly identified and an assessment made as to re-measurement activity resulting in an improved accuracy over time. DCDB data sourced from 1992 base dataset of Linthorpe Valley GIS.180
180 Hannigan B.J., and Webb R.M., 1993, L.I.S. Technology and the Process of Rural Reconstruction, December 1993. 142 pp. Final report of research project sponsored by The Australian Key Centre in Land Information Studies and The Queensland University of Technology, Brisbane.
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Figure 3.4: Enlargement demonstration of cadastral corners requiring corrective re-measurement action. The solid fill of error ellipses indicates residuals exceeding a management performance indicator of 1metre (in this example 1.1 metres). Un-filled error ellipses indicate acceptability to management performance indicator. 181 3.3.9 Increase in Spatial Accuracy over Time
As more measurements of increasing measurement quality are added to the
MBSIS, the accuracy of the system increases. The accuracy of a system that
contains older measurements is low because of the low quality of
measurements. Cadastral traverse measurements from control points to
cadastral evidence points will contribute to an improvement of system accuracy
with the increasing availability of precise instruments to surveyors. This
implicitly suggests that quality measurements are being made over periods of
time, for example, slope distance measurements made today compared to
1970s.
181 Ibid., Enlarged extract from central Linthorpe Valley clearly showing theoretical error ellipses to assist in graphical identification and assessment of problem areas.
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However, an accepted practical criterion will need to consider the nature of
long-standing and undisputed occupation, which could conceivably be at odds
with a purely optimised measurement approach.
Figure 3.5: Sample graph of performance indicator: improvement of relative accuracy in rural boundary locations for a district.182
The converse argument is that the accuracy of a co-ordinate alone based
cadastral system decreases over time. For example, an accurate survey of an
area is undertaken with the results of the survey in the form of accurate digital
co-ordinates of boundary corners alone. The maintenance of an accurate
geometric layer in the form of co-ordinates is difficult. The replacement of lost
points can only be made of an accuracy less than that of the accuracy of the
existing co-ordinates. Therefore, the accuracies associated with the established
points are a combination of the accuracies of the existing co-ordinates and the
new measurements.
For example, if in a rural catchment area, about 5% to 10% of boundary corner
monuments disappear or are destroyed through normal farming activities
annually, then it would take only about 40 to 50 years before the geometric
layer of an area could be deemed useless locally. Traverses from distant
cadastral evidence would require large time and human resources by traditional
Relative Accuracy over Time for a Region
0
0.1
0.2
0.3
0.4
0.5
0.6
1 2 3 4 5 6 7 8 9 10 11
Time (years)
Acc
urac
y (M
etre
s)Series1
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total station techniques to re-locate this lost boundary information. This cost is
difficult to justify to the client who pays the bill. GPS techniques can however
adequately assist with providing an improvement to this specific situation.
3.3.10 Change in Co-ordinate and Derived Metric Values
Buyong (1992) and others have investigated the magnitude and conditions of
changes brought about by the addition of new measurements to a localised area
under consideration. The magnitude of the changes may vary and to a large factor is dependent on the precision of the added measurements. For example, an addition of a precise measurement such as a GPS vector will change the coordinate values more than the addition of a cadastral angle measurement. The number of measurements being added relative to the number of measurements already in the database also influences the magnitude of the coordinate value changes.
Users are primarily interested in relative metric values such as length of a boundary line and area of a parcel rather than absolute coordinates of the related points. When new measurements are added, the relative values vary much less than the coordinate values because the changes are generally in a systematic direction. The systematic change of coordinate values of local points produces a minimal difference in the relative metric values when a system is queried at different instances.183
It is noteworthy that most of the general community are interested in boundary
line lengths and areas relating to a land parcel, not the co-ordinate information
or reference framework (three-dimensional or others), when considering their
legal boundary extents.
182 Speculative graph based on unpublished QUT student projects examination of coordinate cadastre databases over the Linthorpe catchment area. This graph is a reasonable estimate of the improvement of accuracy in the Valley floor area of Linthorpe using original survey plan dimensions and recent Total Station traverse connections of boundary evidence. 183 Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine p.32-33.
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3.3.11 Data Quality Assessment
A foundation principle of a MBSIS is that measurements are stored with their
residuals after the adjustment stage. When assessments are to be undertaken
about the reliability of the measurements, the information regarding the quality
of measurements forms a useful source of knowledge. Dale and McLaughlin
(1990) provide the example of this point where the error estimate of
measurements solves the issue of the reconciliation of measurements that have
been captured to different standards.184
A consequence of a pure co-ordinate based systems approach is the potential
danger that the inherent accuracy is lost when good quality new measurements
are downgraded to forcibly fit into existing co-ordinate values. Dale and
McLaughlin (1990) argue that this is in breach of the principle of consistency
but understandably concede that measurement technology of today is to a much
higher standard than in the past.185
The arguable justification for an alternative solution is the storage of the
individual measurements inherent error estimates, therefore allowing quality
assessments of the measurements possible. Since the measurements combine to
form a matrix pattern (links and bounds between parcels and/or survey control
points) in support of the evidence that best defines the cadastre at a point in
time, the addition of error estimates attached to a pure measurement-based
approach strengthens the argument of providing sound data quality assessment.
Modern co-ordinate collection technology, incorporating acceptable statistical
measures about the measurements themselves and processing techniques
employed (real-time, virtual or classical post-processed), has valuable potential
184Dale, Peter & McLaughlin, John, 1990, Land Information Management: An Introduction with Special Reference to Cadastral Problems in Third World Countries. Published by Oxford University Press New York. Surveying and Mapping examples discussed and issues raised where improvements in geodetic networks and network densification actions are undertaken, pages 100-103. 185 Ibid., p101.
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in improving the spatial accuracies when applied to new cadastral subdivision
actions. The clear communication and feedback relating to repeatability of
measurements and confidence instilled in the results, along with new
descriptions of a third and fourth dimension, adds to the integrity of the
cadastre for these new subdivision areas undertaken with this measurement
focused approach.186 However, in older areas (the typical rural cadastral
situation) the integrity improvement is unable to be realized due to the notion of
best evidence and in many cases the long-standing occupation and other
constructed improvements delineating a boundary.
Modern co-ordinate collection technology may be utilised by a surveyor for the
purpose of spatially locating existing evidence of the cadastre prior to
reinstatement process. However, this co-ordinate collection approach is
unlikely to improve the integrity of the cadastral determination, in the short to
medium term, based on the notion of best evidence for this situation. In rural
areas of broad hectare farming where cadastral ground monumentation has been
destroyed, re-surveys of large land tracts by RTK-GPS techniques with
connections to surrounding geodetic control and cadastral evidence will
justifiably improve the cadastral integrity in this local area.
On this issue of quality assessments of the measurements, Buyong (1992)
states: Only a measurement-based system can support quality assessment for base data and information derived from the data… …The accuracy of metric information can only be visualised if the accuracy parameters of data from which the information is derived are stored in the system. Measurement-based concepts are a major step towards achieving this goal.187
186 Communication and feedback of statistical measures has been covered previously relating tp permoance indicators and communication design criteria Section 2.2.1 and 2.2.2 of this thesis.
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Figure 3.6: Graphical accuracy of parcel boundaries.188 The shaded areas indicate the bound within which the boundary lines may be located. Potential performance indicator based on quality assessment considered at an implementation stage. Error ellipses not-to-scale with respect to boundary representation.
3.3.12 Differentiation between Legal and Non-Legal Metric Values
A MBSIS may contain legal and non-legal boundary measurements relating to
the parcel. The legal boundary measurements come from deed descriptions. It is
the legal bearing and distance measurements that must be used for legal
purposes. A more guided approach to this topic has been discussed within
concepts of cadastral evidence in Queensland, section 2.3, of the dissertation.
It is proposed that reinstated boundaries are held or flagged as a separate entity
from the pure measurement information stored in the database. Hence, from
time to time, the measurements to the cadastral evidence as measured in the
field will disagree (presumably only by a small magnitude of the surrounding
positional accuracy) with the reinstated boundaries based on the justification of
the cadastral surveyor following the principles of best evidence. An example of
187 Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine. Chapter 2 p36. 188 Ibid., p.35.
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this is surveys of ambulatory boundaries with several decades between
measurement epochs.189 Ambulatory boundaries, by their very nature, change
over time due to a number of naturally occurring influences.
The non-legal measurements relating to the parcel are stored in the database
and metric values that result from adjustment of the measurements may be used
for other purposes as described in the vision statements of Cadastre 2014.
Traverse measurements between pins or PSMs may be value-added to include
spatial relationships to other assets including council and utility infrastructure.
Adjusted co-ordinate values alone used to describe a legal parcel corner have
minimal legal standing in most states in Australia. It is recommended that a
fundamental shift to legislate accepting co-ordinates as positions for cadastral
descriptions alone be strongly opposed. This is justified by the notion of best
evidence of boundary location and best-fit based on the surveyors search for
evidence on the ground when conducting a cadastral re-survey.
The description of an asset’s location, relative to the boundary lines, within a
MBSIS approach will have holistic management implications when dealing
with various governments, utility and private organisation’s spatial information.
3.3.13 Digitised Photogrammetric Co-ordinates and Ambulatory Boundaries
Digitised and photogrammetric co-ordinates can be rapidly obtained and are
relatively inexpensive to capture on medium to large planimetric projects
compared to traditional total station field surveys. However, photogrammetric
and digitised co-ordinate data accuracy is low and fits into the lower third
category of measurement types. Digitised data that has had some form of
rubber-sheeting to fit into an existing control network is useful as an
189 Authors experience in check field survey of “Scrubby Creek” creek line boundary and differences encountered between original surveyors field notes delineating top-of-bank traverse offsets in late 1950s and author check field survey by total station traversing 2001 and comparisons with historical aerial photography.
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information source when first implementing a MBSIS. The progressive addition
of new measurements with close-fitting accuracies into an area will result in an
improved accuracy over time. This approach requires less capital investment at
the start of implementation and is applicable to developing property
information systems to provide adequate coverage of regions.190
Buyong (1992) summarises why digitised and photogrammetric derived co-
ordinates cannot be used to deal with updates in measurement-based systems.
• Unreliable accuracy estimates of digitised coordinates make them useless in the updating of a system.
• Digitised coordinates are single-point measurements and thus lack the ability to spread higher accuracy information in the neighborhood.[sic]
• Photogrammetric coordinates cannot be economically obtained in a smaller quantity.191
However, photogrammetric data (image and derived three-dimensional data)
does have a place in engineering projects and provides an image captured at a
particular epoch that can allow historical and other analysis. Photogrammetric
data can be used in an MBSIS structure where the acceptance of lower
positional accuracy is satisfactory, provided a statement of its accuracy is
included in the spatial data usage. The issue of inclusion or exclusion of digital
ortho-rectified aerial photography as an underlying layer to an MBSIS has not
been considered. It is acknowledged that this information source is only
considered as useful as the currency of the image data and the precision and
reliability of the rectification results. However, recent advances of Airborne
Laser Scanning (ALS) data in point clouds format or other four- dimensional
point visualisation could be incorporated into an MBSIS layer, provided the
quality assessment process and potential weighting strategy is considered.
Ambulatory boundaries fall into this third and lower category of measurements
because they are only considered as reliable at the time of survey, and are often
considered as singular measurements collected as offset data. Ambulatory
190 An example of this point is provided through Majid Kadir, 2000, ‘Towards the Implementation of Coordinated Cadastral System in Malaysia: Large Cadastral Network Adjustments’, The Australian Surveyor, Vol.45, no.1, June 2000, p.37-46. 191 Buyong,T.B., 1992, Measurement-Based Multipurpose Cadastral Systems. Ph.D. Thesis, University of Maine,p.38.
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boundaries are to be considered of a lower accuracy order given the changing
nature of the typical natural boundaries. Whilst a high precision survey of this
type of boundary may yield an adequate boundary demarcation, it must be
acknowledged that these predominantly natural boundary features do move and
change over extended timeframes. The requirement of legal evidence and its
somewhat higher weight assignment in the reinstatement process, make these
types of boundary more difficult to accommodate in a measurement-based
system. However, the measurements obtained at time of survey can yield by-
product information for temporal studies of natural boundaries. For example,
the slow changing nature of a boundary associated with a meandering creek-
line with the parcel “bounds” described as the top of bank. Naturally, the tops
of bank and creek contents suffer natural processes of erosion and accretion.
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3.4 MBSIS Information Integration
Several attempts in the last decade have been taken to further the survey data
integration issue into many other information layers. However, the underlying
assumption for correct integration of different layers of information (usually of
various vintages and quality) is provided through the co-ordinate values of
parcels and its framework.
The information layers may be either described as loosely or tightly integrated.
This will ultimately depend on the level of integration of the contributing
organisations datasets.
A description of a loosely integrated information system is that of data layers
residing in several databases. Data collections and maintenance of a specific
data layer should be the primary responsibility of its proprietor - with other
organisations being allowed read-only access to that data/information as
necessary.
An example of a loosely integrated land information system is the South
Australian Land Ownership and Tenure System (LOTS) as outlined by
Sedunary (1984).192 Borchardt and Lunnay (1992) also briefly discussed this
system with the establishment of high quality GPS control networks and the
transition to a legal co-ordinated cadastre for South Australia.193
Description of a tightly integrated information system is that all data layers
reside in a single database in a logically organised manner. Maintaining the
data layers can be undertaken by the database proprietor, or as subcontracted to
specific organisations that can meet an imposed spatial information
specification or standard. Examples of tightly integrated systems include: Land
192 Sedunary, M.E., 1984, 'LOTS, and the Nodal Approach to a Land Information System.' Proceedings of the FIG Symposium on Land Information Systems for Decision Makers, Edmonton, Canada, pp.69-80. (cited in Buyong, 1992) 193 Borchardt,D., and Lunnay,C., 1992, ‘Underpinning a Legal Coordinated Cadastre - The South Australian Experience,’ paper presented ISA northern group meeting, 16 pages, Cairns, May 1992.
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Registration and Information Services (LRIS) from Canada as discussed by
Roberts (1978);194and the Canberra ACTMAP system as discussed by Eeles
(1996).195
During the early 1980s, Queensland began to capture the Digital Cadastral
Data-Base (DCDB). Reviewing the actions and policy directions for this
initiative, the main idea for the DCDB creation was as a digital version of the
existing paper working maps used throughout governmental departments.
This, along with reasons of costing and timing (political expediency), meant
that decisions were made to capture DCDB by digitising (digitised hard copy
data with all its inherent errors instead into a co-ordinated based system) the
best available cadastral mapping with a relatively sparse level of survey control.
It appears to have been made clear to clients that the intention was to pursue
state-wide coverage of digital mapping. Justification against using numeric
data entry at the time appears to revolve around the following: • excessive cost, • excessive delays before a finished product was available, • unnecessary accuracy requirement.196
A number of large organisations began using the DCDB for their own land
management functions and some began to find a need for higher spatial
accuracy for certain applications (local government and utility companies). In
some arenas and forums, the DCDB had become a victim of its own success in
that users of DCDB have realised the potential of digital map data and
developed a serious enthusiasm for better spatial data.
194 Roberts, W.F., 1978, 'Report on Land Registration and Information Service, Maritime Provinces, Canada.' Proceedings of 2nd Conference on Modernization of Land Data Systems, Washington, DC. (by way of Buyong, 1992) 195More recent information can be found on this information system http://www.palm.act.gov.au/ (September 2000) Eeles, A., 1996, ACTMAP - A Data Management Tool for Mapping in the ACT. Proceeding of Mapping Sciences'96 - Mapping for Management, Canberra., Mapping Sciences Institute of Australia, p308-312. 196 Baker, K., 1991, ‘Positional Accuracy Considerations for a Digital Cadastral Data Base,’ Proceedings of Symposium on Spatial Database Accuracy, Department of Surveying and Land Information, The University of Melbourne, June, p.37.
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However, the primary providers of this spatial information, the surveyors, are
often jettisoning their primary measurements and supply derived data in the
form of paper-based cadastral survey plans or engineering plans. This loss of
information through communication channels is reiterated by the following
example. This can be seen insignificant where entropy is viewed as the measure of disorder in a communication system. As an example, the documentation of the cadastre is a long and complex cycle working from the intent of the owner, the ground monuments and previous surveys through to the computer on to a paper -based plan in the surveyors office, then converted back to digital format at the Department of Natural Resources (DNR). This information is then sent on request to various parties whom then may inturn use this information as part of a new survey. Vast amounts of information are lost and/or distorted in the process. This occurs mostly from the changing from a digital format to a paper-based format. When held in a digital format all the redundancy and accuracy of the survey is contained within the digital data, this is converted to lines and text on a paper-based map. The amount of accuracy lost when translating this data back into digital form depends on the method used. The digitising and scanning methods used previously have resulted in the loss of significant detail and accuracy. This has lead to the manual re-entry of the bearing and distance of each boundary line, where possible or practicable.197
However, the Queensland Government, through the Department of Natural
Resources and Mines, have been aware of the limitations of the original DCDB
and have recently invested in progressing towards improving the DCDB to a
survey-accurate cadastral representation as outlined in a forward thinking,
departmental discussion paper.198 This has relation to the hypothesis under
question because of the various identified maturity levels of the urban and rural
cadastre.
197 Cook, J.S., 1991, 'Some policy issues involved in digital land boundary information', Proceeding of QUT Winter School - Management of Cadastral Information, School of Planning, Landscape Architecture and Surveying, p.5. 198 Todd,P.,Higgins,M., and Williams,G., 2000, An Enhanced Survey Observation Management Environment - Discussion Paper, surveying and mapping section, Department of Natural Resources, Queensland.
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Table 3.2: Levels of Maturity for Cadastral Representations in Qld.199 The levels of maturity for survey infrastructure identify recognisable steps in a developing digital environment. Each level provides increased opportunities for stakeholders.
The table above represents the progressive levels, terms and stages to realising
a legal cadastre as it may apply in Queensland at some distant point in the
future. The maturity levels of common stages of a digital cadastre are presented,
which could conceivably provide a framework for implementation strategies in
developing countries considering enhancement to their cadastral representation
systems and land titling administration.
It is at the level of Survey Accurate Cadastre representation that a
measurement-based approach could most achievable be implemented. The
representations of cadastral characteristics at the survey accurate level
introduce the dimensions of lots. It is this level that the integration of a MBSIS
could operate in parallel with the current scheme, within a local controlled area,
until such time that the benefits of the MBSIS surpass the current scheme.
In consideration of the operations of a survey practice adopting the MBSIS over
the current scheme, the cadastral data cycle diagram below is essentially
unchanged except for changes in procedures at the data submission stage
whereby measurements would be submitted via digital lodgement avenues.
199 Todd,P.,Higgins,M., and Williams,G., 2000, An Enhanced Survey Observation Management Environment - Discussion Paper, p.4., surveying and mapping section, Department of Natural Resources, Queensland.
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Figure 3.7: Cadastral data cycle for both current and proposed scheme.200
Previous efforts by several organisations have endured to progress the issue of
survey integration as various institutional levels.201 A National Cadastral Data
Model is being developed and refined from a review of cadastral data models
supplied by jurisdictions in Australia and New Zealand. The National Cadastral
Data Model is an initiative of the Intergovernmental Committee on Surveying
and Mapping (ICSM) as part of its ongoing work towards developing the
Australian Spatial Data Infrastructure (ASDI).
This data model is intended to serve a number of purposes:
• to describe digital cadastral information, • to integrate the cadastre with other land systems, • to be an agreed model for the specification of digital cadastral
databases, • to be used with the ICSM Cadastral Data Dictionary, • to be an agreed model for the specification of digital data
transfers, and • to test/specify new technology requirements.202
200 Derived from Ibid.,p.7. 201 Dawson, P., 1995, A Model to Progress Survey Integration- Discussion Paper, jointly prepared by Department of Lands (Qld) and The Institution of Surveyors, Australia (Queensland Division) 202 ICSM, 2001, The National Cadastral Data Model Version 1.1, information available on-line Internet http://www.anzlic.org.au/icsm/cadastral/ncdm11.htm (accessed December 2001) This is a revised data model with a published date of June 1999 with subsequent amendments.
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It is the last two points of the above summation in which the concept of a
measurement-based cadastral representation conceivably holds promise.
However, major institutional cultural changes would be required in the
implementation of such a system. A measurement-based approach would be
highly compatible with the nationally-directed approach of multi-layer cadastral
data model, with particular relevance and complementary integration to the
survey entities descriptive section.
Dale and McLaughlin (1990) indirectly add to this argument when discussing
development of a unified land information system, and highlight the previous
point of minimum standards to satisfy management objectives in a practical
manner, thus:
The point has to be stressed, for progress towards the development of unified land information systems is being seriously retarded by a failure to determine what, in the overwhelming majority of cases, are the minimum standards that are both necessary and sufficient for almost all practical purposes. There are, of course, certain circumstances under which precise measurements for detail surveys are right and proper. To argue that all surveys must therefore be to this standard is illogical and leads to a serious waste of resources and lack of productivity. For each task, the most appropriate technique should be used.203
Given the historical development of survey related databases in Queensland, it
is suggested that for all survey related functions (DCDB, Survey Control Data
Base-SCDB, geodetic networks etc) that a tightly integrated information system
in the form of a MBSIS could be implemented with existing standard database
architecture. This could operate within a distributed information network and
suitable interfacing as per the current status of many Queensland Government
information databases dealing with broad location-based data. While Buyong
(1992) has examined benefit/ cost ratio relationships of implementation in a
local district (a rural US county), the issue of so called tight information
integration requires further pragmatic research.
The development of MBSIS concepts has been advanced by the recent
technological development of computers in not only the office environment but
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by the increasing incorporation into surveying instrumentation and database
management software. Quality surveying measurements from total stations or
GPS instruments, instead of processed co-ordinate information, are stored in a
database of a multipurpose cadastral system and form the basis of metric spatial
information. The measurement storage and survey management is but one sub-
set of the larger system. Co-ordinate values are still the most convenient and
easiest to conceptualise. The processing and role of measurements can be seen
as nothing more than a convenient way to supply the co-ordinates and provide a
justification for those co-ordinates.
Figure 3.8: Conceptual relationship between survey measurements and co-ordinates.
This dissertation advocates that co-ordinates are but one representation of a
spatial situation driven by a necessity to summarise a spatial situation. The
addition of a measurement-based information system where the measurements
are consulted for every query adds tremendous strength to local and regional
management of survey problems and cadastral integrity.
203 Dale, Peter & McLaughlin, John, 1990, Land Information Management: An Introduction with Special Reference to
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The cadastral fabric of Queensland is a dynamic entity. With changes
occurring over time, the issue of the integration of this time element to this
system requires further consideration in light of management performance
measures. Al-Taha (1992) discusses various issues and concerns relating to
geometric relationships to time and time integration with cadastral management
in his findings.204 Examples of this time integration theme include such
management issues as:
(a) time representation (the cadastral representation in LCA region 4 at the
31st of December 2000 was …) and,
(b) time perspective (the last two working days of each month indicated
greatest activity).
Although this time integration issue is not seen as an impediment, it could
merely be a requirement that actions (survey measurements) are time-stamped,
so that time requirements necessary for cadastral system operations can be
better managed. This also provides some basis for measures of management
performance as previously indicated in Cook’s (1994) operational
accountability regimes.
Cadastral Problems in Third World Countries. Published by Oxford University Press New York. Page 126. 204 Al-Taha, K., 1992, Temporal Reasoning in Cadastral Systems, Ph.D. Thesis, Department of Surveying Engineering, University of Maine.
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3.5 Summary
The fundamental concepts of a measurement-based spatial information system
with emphasis on the application to cadastral surveying have been explored.
The storage of foundation measurement information within a MBSIS for the
intent of future use and the addition on new quality information for the purpose
of improving the spatial accuracies for a parcel (as an example) have been
shown.
The issue of improving a system’s accuracy over time by increasing the data
population with improvements in input measurement accuracy has additionally
been explored. It is foreseeable that real-time GPS surveys will improve in
quality from the current planimetric accuracy of 15mm- 50mm (approximately)
to 5mm -20mm planimetric accuracy. However, to be of use, a documented
outcome in the form of a GPS vector summary with explicit error analysis
would be required for quality assessment into a MBSIS. Re-analysis issues and
re-adjustment issues with a variety of weighting strategies of previous spatial
information is also possible if the measurements themselves and accuracy
measures have been stored. Further implementation study is required of the
technical issues of applying weighting strategy within the constraints of a least
squares adjustment analysis.
In reinforcing the issue that surveyors often jettison much of the primary
information collected to produce a hard-copy non-digital summary plan, the
concept of a measurement-based survey information system can benefit many
stakeholders over and above the current non-efficient methods of spatial data
production.
It is recommended that a fundamental shift to legislating acceptance of co-
ordinates as positions for cadastral descriptions alone be strongly opposed. This
is justified by the notion of best evidence of boundary location and best-fit
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based on the prescription of the Surveyors Operation Manual (QLD). It is the
art and science of a professional surveyor’s search for evidence (best evidence)
on the ground when conducting a cadastral survey that sets them apart from
amateurs.
It is acknowledged however, that further research is required into the area of
standard data collection formats for electronic total station, GPS techniques and
evolving measurement technology approaches (including verification, test
comparisons or others) that may eventuate.205 Further research is also required
into avenues of digital data lodgement of standardized measurement based
spatial information into a central database in light of national efforts to build
spatial infrastructures including a unified cadastral model.
It is recommended that a measurement-based approach be adopted within local
controlled areas, preferably excluding regions of geological instability
potential. Further research is also required to explore the costs associated with
an implementation and the desired and actual foreseeable benefits (tangible or
other) from such a proposal in a Queensland context. This would normally be
undertaken as part of a detailed pilot study requiring rigorous analysis and
what-if scenarios on a small test area with diverse characteristics. This chapter
has explored conceptual aspects of MBSIS in a Queensland environment with
some emphasis towards issue of GPS derived positioning information.
205 Steggall, S., 2001, Evolution of Digital Reinstatement Methods within Private Organisations, Master of Applied Science (Research) Thesis, Qld University of Technology.
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CHAPTER FOUR
SURVEY CONTROL FRAMEWORKS AND
INFRASTRUCTURE
It is interesting thus to follow the intellectual truths of analysis in the phenomena of nature.
This correspondence, of which the system of the world will offer us numerous examples, makes
one of the greatest charms attached to mathematicall speculations.206
4.1 Introduction The purpose of this chapter is to examine and explore foundation issues in
proposing a measurement-based information system applied to a Local Controlled
Area with suitable geodetic monitoring network. This chapter focuses upon the
survey control frameworks at global and regional scale. A suitable technically
efficient geodetic network would further strengthen and support the efforts of
broadening the Australian Spatial Data Infrastructure (ASDI) and provide
scientific knowledge in the area of regional geodynamics.
206 Pierre-Simon Laplace quotation 1799. Cited in O'Connor J.J, and Robertson E.F., 2000, Biography of Pierre-Simon Laplace and article on Orbits and Gravitation. Published by School of Mathematics and Statistics University of St Andrews, Scotland.
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The linkage between cadastral systems and geodetic networks is not a new
concept. Many government and land related institutions acknowledge that
spatially related information in its various forms be integrated by a common
reference framework At its simplest level, the function of a spatial information system is to answer two questions: “What is Where? And Where is What? Expressed in another way, given a particular object or set of objects, the system should be able to determine where those objects are in space; or given a particular location the system should be able to specify what occurs at any given point. Implicit in such a simple concept is the existence of a frame of reference that can define the “where”.207
GPS measurement techniques are becoming just another instrument in the
modern-day surveyor’s measurement instrument toolbox. Foundation
requirements of geodetic surveying applications are to ensure adequate
redundancy and reliable positional information. Differential GPS provides four-
dimensional, reliable information, with somewhat copious redundant data
depending on the method utilised for an appropriate application without the
traditional angle+distance survey requirements of:
• intervisibility between stations,
• the designing of the network to give near equilateral triangles or braced
quadrilaterals,
• field-work during traditional daylight hours.
GPS measurement approaches can virtually be utilised 24 hours a day dependent
on satellite numbers, geometric quality and a favourable topocentric sky-looking
perspective. However, in the regional context of spatial land information systems,
the function of such a geodetic network is to define a unique reference framework.
This framework then provides a consistent base reference at local, regional and
national scales through which all mapping, field surveys, and other attribute
collection activities are spatially integrated.
207 Dale, Peter & McLaughlin, John, 1990, Land Information Management: An Introduction with Special Reference to Cadastral Problems in Third World Countries. Published by Oxford University Press New York, p.85.
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4.2 Geodetic Positioning Geodetic positioning can be described as the high-precision determination of one,
two or a group of three or more co-ordinate sets of data on land, at sea, or in space
with respect to a predefined co-ordinate system. Defined co-ordinate systems are
usually held fixed for a time until an improvement of knowledge and/or
measurement methods dictate that an improved reference model is better suited to
the users of the co-ordinate system.
In essence, geodetic positioning is about making measurements that link unknown
points to high-precision points of known co-ordinate values that have been
derived from either terrestrial points or extraterrestrial objects such as stars or
satellites or both. Geodetic positioning must be considered as four-dimensional in
nature (X,Y,Z and time T) as physical changes and improved processing
techniques are occurring that effect particular relationships in comparing one
dataset, a model of reality, to another separated by time-span T.
The separation of time between surveys in rural Australia presents a scenario
highly aligned with the statistical “stock” concept. The stock concept involves the
description of a system at a particular instant in time. The “flow” concept
describes changes to the system over a period of time or accounting period.208
Measurements of discrete variables relevant to stock and flow concepts are aids in
describing the dynamic nature of particular phenomenon.209
Geodetic positioning can be classified into point positioning, relative positioning,
and network positioning. These fundamental positioning concepts can be
succinctly summarised as:
• Point Positioning – determining the positional co-ordinates of one point.
208 Cook, J.S., 1999, Urban and Regional Economics Lecture 02 Notes PSB611- Basic Stock and Flow Concepts in Economics, Queensland University of Technology. Available Intranet http://www.dbe.bee.qut.edu.au/people/cookjs/psb611/611/611lec02.htm (accessed Jan 2003) 209 Australian Bureau of Statistics, 2000, 5216.0 Australian National Accounts: Concepts, Sources and Methods, Chapter 7:flows, stocks and accounting rules, variable pp., ABS-Statistical Concepts Library, Available on-line Internet via http://www.abs.gov.au (accessed Jan.2003)
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• Relative Co-ordinates – determining the relative location of one point
with respect to another.
• Network Positioning – determining the relative locations among a group
of three or more points respectively to each other.
A geodetic network in its ideal form can therefore be defined as being any
geometrical configuration of three or more terrestrial survey points that are
connected either by geodetic measurements made among such points as:
• horizontal directions, angles, spatial distances;
• or by astronomical and/or space techniques;
• or a combination of both.
Therefore, it is arguable that the type of point positioning and relative positioning
may be considered special cases within a network positioning approach. This is
relevant to the hypothesis being tested given the issues of co-ordinate collection
techniques and emerging technologies in surveying and mapping applications.
As discussed in the works of Grafarend and Sanso (1985),210Vanicek and
Krakewsky(1986),211 Leick(1995),212 Kuang (1996),213 amongst others, the main
functional area where geodetic control networks are needed include:
• the broad realm of mapping;
• boundary demarcation, for example positioning and survey setting out of
local, provincial and international boundaries);
• urban management;
• mining and engineering projects;
• geographical and land information systems (GIS/LIS);
• hydrography and near-shore environmental studies;
• environmental resource management;
• geophysical applications;
210 Grafarend, E.W., and Sanso, F., 1985, Optimization and Design of Geodetic Networks, published Springer-Verlag:
Berlin. 211Vanicek P. and Krakewsky E.J., 1986, Geodesy: The Concepts, -Second Edition, Elsevier Science Publishing Company, Amsterdam; New York: North-Holland 1986. 212 Leick A., 1995, GPS Satellite Surveying, –Second Edition, John Wiley and Sons Inc., New York/ Chichester/ Toronto/ Brisbane/ Singapore. 213 Kuang, S.L., 1996, Geodetic Network Analysis and Optimal Design: Concepts and Applications, published by Chelsea, Michigan: Ann Arbor Press.
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• ecology studies;
• aerial photography;
• space research and many others.
A common feature for these mentioned applications is a framework of points with
known horizontal and/or vertical co-ordinates with respect to a predefined
reference system. More often than not, it is very recent three dimensional
reference positions that are required to control an application to provide the
necessary spatial information in a homogeneous dataset.
The following figures are derived from practical work undertaken with electronic
total station equipment and GPS instrumentation in the Linthorpe Valley rural
project area.
Figure 4.1: Sample geometry of rural cadastral survey using traditional total-station techniques. Location- Linthorpe Valley, Darling Downs. The small triangles represent 5 traverse stations with dependence on line of sight and contain measurement radiations to cadastral evidence (R.F.P.s , pins/corners, fencing occupation, etc)
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Figure 4.2: Sample geometry of rural survey using modern RTK-GPS techniques. Location- Linthorpe Valley, Darling Downs. The small squares represent controlled base stations (2 in total) and contain measurement radiations to cadastral evidence that is not dependent on horizontal line of sight obstructions. The network geometry is sound, contains closed traverse links and less set-up stations compared to traditional total-station techniques on same land parcel. In this application a number of trees and farm building contained on the subject block that required visibility considerations for total-station traversing. This work involved creating a cadastral database layer and information integration
with field survey observation information and construction of a GIS for a number
of research purposes.214 These figures clearly demonstrate the geometry involved
in conducting a simple rural cadastral survey using a traditional total station
survey compared to utilising an RTK-GPS technique.
214 The following five references outline the main multiple research projects in this geographical area: Hannigan B.J, 1992,
Re-arrangement of Cadastral Boundaries to Facilitate Optimum Rural Land Use, December 1992. 96 pages. Published by School of Surveying, QUT. Final report of research project funded by The Surveyors Board of Queensland, Brisbane.
Hannigan B.J., and Webb R.M., 1993, L.I.S. Technology and the Process of Rural Reconstruction, December 1993. 142 pages. Final report of research project sponsored by The Australian Key Centre in Land Information Studies and The Queensland University of Technology, Brisbane.
Hannigan B.J. and Farmer R., 1995, Rearrangement of Farm Boundaries to Facilitate Beneficial Adjustment in Primary Industries, Final report of research project QUT-2A funded by Rural Industries Research and Development Corporation pp.162. Published by School of Planning, Landscape Architecture and Surveying, Qld University of Technology, Brisbane.
Hannigan B.J. and Webb R.M., 1995, Rearrangement of Property Boundaries to Facilitate Optimal Rural Land Use, Final report of research project UQT-1 funded by Land and Water Resources Research and Development Corporation (LWRRDC R&D Project UQT-1) pp 9. Published by School of Planning, Landscape Architecture and Surveying, Qld University of Technology, Brisbane.
Webb R.M., 1996, 'Mapping for Future Land Management: Mapping for a Proposed Land Boundary Re-Arrangement in a Rural Queensland Catchment.' Proceedings of Mapping Sciences'96 -Mapping for Management, Mapping Science Institute of Australia, Canberra National Convention Centre. pp.397-419.
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Findings from this practical and experimental rural property surveying and asset
data collection work found that although GPS has some limitations, it is
demonstrably an efficient surveying tool producing high quality data for
surveying and mapping applications. GPS has also been an efficient surveying
tool for engineering and cadastral survey applications when utilised by an
informed and educated operator under proper operational conditions.215 This view
is further supported by relevant literature and applied GPS investigation
studies.216
4.3 National Geodetic Framework
Early datum definitions for national geodetic control networks in Australia were
largely achieved by initial astronomical measurements techniques together with
making some theoretical assumptions when processing the first observations for
first order control. In Australia, this was predominantly Clark,217 pre-1965, and
later influenced by works of Bomford (1971)and Mackie (1971) for regional
continental scale geodetic networks. 218
All subsequent survey observations extending and densifying the national
networks relate to the national datum by observations connecting new points with
points fixed within the reference frame. In 1966, the first national datum was
215 Based on the authors 12 years experiences in GPS use (hydrographic and land applications) and recent Trimble Navigation Ltd “Certified GPS Trainer” status 2001, 2003. 216 The following six references support the applied investigation studies: Gerdan, G.P., 1991, ‘Rural Cadastral Surveying
with the GPS,’ The Australian Surveyor, Institution of Surveyors Australia, Sept., Vol.36 No.3, pp184-194. Collins, B., 1992, ‘GPS - The Next Big Thing in Cadastral Mapping? The Application of the Global Positioning System
(GPS) for the Coordination of existing Cadastral Information,’ Proceedings of AURISA'92 - 20th International Conference of AURISA. Gold Coast, Australia pp.238-249.
Hoogsteden C., Denys P. and McDaid D., 1997, 'Cadastral surveys and the GPS option: Origin definition, time and cost comparisons for an urban cadastral survey'. Trans- Tasman Surveyor, jointly published by Australian Institution of Surveyors Australia and Institution of Surveyors New Zealand, vol.1, no.2 July, pp45-52.
Londe M., 1998, ‘Guidelines for using GPS on Large Scale Cadastral Surveys (Wyoming & Nebraska)’, Proceedings of 1998 Trimble User Conference. Trimble Navigation Limited. pp.4.
Stock, K.M., 1998, ‘Accuracy Requirements for Rural Land Parcel Boundaries’, The Australian Surveyor, Vol.43, No.3, September 1998, pp165-171. (Specifically in the Linthorpe Valley project study area).
Large P., 1999, ‘GPS Control Network Design and Logistics for Linear Engineering Projects,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited. pp.13.
217 Clark, David, 1948, Plane and Geodetic Surveying for Engineers – Volume Two, Higher Surveying. 3rd edition 2nd reprint 1948. Published by Constable and Company London. 218 Bomford G., 1971, Geodesy. Third Edition, Published by Oxford University Press, London. In particular chapter 4 Geodetic Astronomy and Chapter 5 the theoretical application of Geometrical Use of Artificial Satellites. ALSO Mackie J.B., 1971, The Elements of Astronomy for Surveyors. Seventh Edition 1971 Published by Charles Griffin & Company, London. In particular the modelling of atmospheric delay of the speed of light into Earths atmosphere depending on elevation above horizon.
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established -The Australian Geodetic Datum (AGD). It was a best fit of the
Australian region at the time, with its reference ellipsoid centre offset from the
Earth’s centre of mass but providing a coherent representation of the Australian
continent.219
Some limitations and problems with this conventional approach for geodetic
network datum definition must be noted.
Firstly, the old positions of the national geodetic control points were obtained at a
time when accuracy of geodetic measurements was lower than that available and
achievable today with modern geodetic instruments. The positioning accuracy
available today could be of one order or better than previous instrumentations and
techniques.
Secondly, there are cases in which the required accuracy of a newly established
network; for example, networks established for high precision engineering and
deformation monitoring purposes where this local network is much higher than
that of the surrounding existing national control. As an example of this point, refer
to:
• the work of Harris (1998) at Karangi Dam (author’s fieldwork
involvement in this project, see Figure 4.4); 220
• Cowie’s (1999) comments on specific regional adjustments; 221 and
• Petersen’s (1992) experiences in a geologically active region; 222
• the author’s involvement in geodetic GPS connections surrounding
McDonald Dam, Pomona region to introduce geodetic control for high
precision structure monitoring.223
219 National Mapping Council of Australia, 1972, The Australian Map Grid Technical Manual, 2nd edition Special Publication number 7, Australian Government Publishing Service, Canberra, introductory chapter. 220 Harris M.W., 1998, ‘GPS and The Karangi Dam,’ Proceedings of FIG Commission 6 (Engineering Surveys) International Surveyors Congress, Brighton, United Kingdom 1998. 221 Cowie M.,1999, ‘The Qld Geodetic Network – Adjusting to GDA94.’ Proceedings of Survey’99 Ccongress, Qld Institution of Engineering and Mining Surveyors Australia. Sunshine Coast October 1999 pp.21. Of special note is the Rockampton-Mackay region with presumed absolute accuracy of AMG84 – referring to graphical presentation of vector shifts as summary. 222 Petersen C., 1992, ‘Precisely San Diego’. GPS World, April 1992, Vol..3,No.4, pp.25-29. Of note is planning and first epoch observations of large geodetic control network with data on PSMs across geologically unstable foundations. 223 Unpublished work in progress and continual monitoring of spillway structures – see Harris 1998 for previous application approach.
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In these cases, it can be argued that adopting the national datum at its assumed
block precision would degrade the results with independent networks required to
be established for project objectives. Often a local datum chosen in an optimal
approach depends on the purpose of a particular network, implementation criteria,
and expected results and outcomes. A more recent example of this situation can
be further explored in the work undertaken by Broadbent and Martin (1999), with
reference to a leading edge application of chart datum for hydrography with GPS
project results of Gladstone region with both land and near-shore points.224 The
quality of the surrounding old datum (AGD84) is questioned when new precision
geodetic networks are established for a particular regional application.
Thirdly, conventional procedures usually over-constrain the network itself, that is,
more co-ordinates are fixed than necessary to provide the new network datum. In
the particular case outlined above, the geometry of the network is affected by the
strains imposed on the network. In Abou-Beih and Al-Garni (1996), arguments
arise when dealing with precise geodetic networks and variable datum
transformation parameters, ……it should be noted that the accuracy of a proposed method depends on the major factors of configuration (coverage and distribution) of the data points and their order of accuracy (first-order, second-order etc).225
This third argument however, can be surmised as to where does the adjustment
process become too overwhelming and the inherit benefits of a fully constrained
GPS network adjustment become so problematic that results are unacceptable for
a majority of further precise applications.
The method of least squares is the most popular in terms of providing an
adjustment to survey measurement information because of the statistical testing
and reportable outcomes including positional error ellipses. Summarising the
foundations of applying a mathematical least squares adjustment process to a GPS
network observation campaign, after the obvious blunders and mistakes have been
224 Broadbent J., & Martin R., 1999, ‘Chart Datum for Hydrography by GPS’, Proceeding of Survey’99 Congress, Sunshine Coast, October 1999, pp.23. 225 Abou-Beih O.M., & Al-Garni A.M., 1996, ‘Precise Geodetic Positioning based on the concept of Variable datum Transformation Parameters.’ The Australian Surveyor, Vol.41 No. 3, 1996, p.214-220.
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removed, two major phases occur in the least-squares procedure. Those phases
are:
(a) Minimally constrained adjustment carried out to detect the internal precision
and consistency of the field observations. Usually no single control point is held
fixed and software packages such as Trimnet will use inner constraints to allow
the adjustment to proceed via using the centroid of the unadjusted co-ordinates to
control co-ordinate translations. In essence, the minimally constrained phase
means that only one set of horizontal co-ordinates are fixed or constrained. This
puts the network in the correct location in space, and the other co-ordinates can be
derived relative to the fixed values.226
(b) Fully constrained adjustments performed to merge the current network into
the existing fixed control. Usually all fixed control points are held fixed to their
known or published positions and the remainder of the network is adjusted to fit
them.227 Typically, this second step of the GPS adjustment process is used to
compute final co-ordinates and estimated errors for the control stations. This
phase is also commonly used for datum transformation of observations, and for
transforming GPS observed delta ellipsoid heights to delta ortho-metric heights.228
A least squares statistical test designed to aid in identifying those observations
which are likely candidates for rejection, is the Tau Criterion. This statistical test
is a reasonable way of answering the old question, ”How big is too big?” when
looking at residuals.229
Consideration will be needed of the decision support criteria for the geodetic layer
becoming populated with newer measurements and presumably improved
226 Hassler R., 1999, ‘Introduction to Network Adjustment,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited, page 14. Note: This document is suitable for undergraduate level geodesy studies in exposure to Least Squares approaches generally and the measures of statistical success or rejection when using Trimble Geomatics Office software. 227 Particular reference is made to chapter 12 Least Squares adjustment of over-determined models and chapter 13 Assessment of results contained within Vanicek P. and Krakewsky E.J., 1986, Geodesy: The Concepts -Second Edition, Elsevier Science Publishing Company, Amsterdam; New York: North-Holland. 228 Useful foundation concepts and explanation of terms can be found in the Surveyors Commentary sections of Trimnet Plus Survey Network Software Users Manual published by Trimble Navigation Ltd (1992+). Of special reference is chapter 8: commentary- the surveyors practical guide to least squares; chapter 9: commentary- GPS error propagation; and chapter 10: commentary- geodetic modelling in TRIMNET. 229 Hassler R., 1999, ‘Introduction to Network Adjustment,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited, page 12.
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precisions over time. Another area requiring mathematical research is to address
the question of at what practical level is adjustment required to decide when new
measurements are forced to fit old measurements and when to perform a larger
adjustment of a region and the justification for doing so.230
Surveyors are educated and trained to collect spatial data using accurate and
reliable measurement tools following proper field procedures. Surveyors also
require observation redundancy and statistical analysis of the solutions to resolve
any problems associated with some poor data sets. With proper field practice and
processing techniques, the surveyors overall confidence in the results of their
work increases.
However, when problem GPS data sets do occur, they are often related to
variations in predicted modeling of ionosphere, troposphere, multipath effects and
centering with height estimates of the geodetic antennae. Of these the most
prevalent and hardest to detect and provide corrective action for is the error
associated with multipath effects. According to Leroy and Peronto (1999), the
best solution would obviously be to avoid it with careful planning and execution
of surveys.231 Practical experiences have shown longer occupation and
observation data allows selected editing and dismissal of the questionable data
based on threshold criteria.
230 Blair, G, 1996, ‘Mathematical Checks’, Proceedings of Seminar'96, Re-Instatement: Principles and Practice, Association of Consulting Surveyors, Queensland, Brisbane. 231 Leroy E., and Peronto, S., 1999, ‘Graphically Analyzing and Recovering Suspect Data,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited, page 2.
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4.3.1 International Compatibilities
The International Association of Geodesy (IAG) is a scientific organization in the
field of geodesy. It promotes scientific cooperation and research in geodesy on a
global scale and contributes to it through its various research bodies. It is an
active member of the International Association of Geodesy and Geophysics
(IUGG) which itself is a member of the International Council for Science
(ICSU).232
In 1988, the Intergovernmental Committee on Surveying and Mapping (ICSM)
decided that Australia would move to the earth-centred co-ordinate system,
GDA.233 In line with recommendations by the International Association of
Geodesy, a geocentric datum for Australia should be based on, and aligned with,
the International Terrestrial Reference System (ITRS) and the ellipsoid associated
with this datum will be the Geodetic Reference System 1980 (GRS80) ellipsoid.
In 1990, the International Federation of Surveyors recommended that its members promote and support the adoption of a global geocentric reference system proposed by the International Association of Geodesy. In 1991, the 56 member maritime nations of the International Hydrographic Organisation (IHO), recommended the production of future navigational charts on a geocentric datum. In May 1994 at the UN Regional Cartographic Conference for Asia and the Pacific, all member countries resolved to adopt a geocentric datum as soon as possible. The International Civil Aviation Authority (ICAO) has decreed that WGS84 will be used for its activities, commencing 1 January 1998.234
Arguably, the Australian surveying industry and others are now realising the
benefits of the Geocentric Datum of Australia (GDA). The GDA is a ‘status
realisation’ of the International Terrestrial Reference Frame 1992 (ITRF92) at
epoch 1994.0.235
The International Earth Rotation Service (IERS) has been established since 1988 -
jointly by the International Astronomical Union (IAU) and the International
232 Schwarz K.P., 2002, ‘What is the IAG?(International Association of Geodesy),’ Proceedings of Geodesist’s Handbook 2000 – Manuel du Geodesien, Available on-line Internet http://www.gfy.ku.dk/~iag/HB2000/summary.htm (accessed Dec 2002) 233 ICSM, unknown date, International Support – Intergovernmental Committee for Surveying and Mapping – Geocentric Datum for Australia GDA homepage. Available on-line Internet http://www.icsm.gov.au/icsm/gda/index.html#IntlSupport (accessed Feb. 2003) 234 ibid. 235 ICSM, 2002, Geocentric Datum Australia (GDA) Technical Manual, version 2.2 February 2002. available on-line Internet http://www.icsm.gov.au/icsm/gda/gdatm/ (accessed May 2003) variable pp.
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Union of Geodesy and Geophysics (IUGG).236 The IERS mission is to provide to
the worldwide scientific and technical community reference values for Earth
orientation parameters and reference realisations of internationally accepted
celestial and terrestrial reference systems.
The concept of ITRF has only been in accepted existence since 1991. A
cornerstone paper by Boucher & Altamimi (1996) for the ITRF concept and its
relationship to the GPS outlines specifics of datum definitions, transformation
parameters between ITRF solutions and ITRF and GPS relationships. 237 ITRF is
a global network of accurate positioning facilities communicated in the form of
co-ordinates and their site velocities, maintained by the IERS and derived from
other geodetic observations techniques such as:
• V.L.B.I. – Very Long Baseline Interferometry;
• S.L.R. – Satellite Laser Ranging;
• G.P.S. – Global Positioning System; and
• D.O.R.I.S. – Doppler Orbitography and Radio positioning Integrated by
Satellite.238
Reference System Realisation Datum International Celestial Reference System
(ICRS)
International Celestial Reference Frame
(ICRF)
International Terrestrial Reference System
(ITRS)
International Terrestrial Reference Frame
(ITRF), current realisation is ITRF2000
International Terrestrial Reference System
(ITRS) ---Geocentric Datum of Australia239
Geocentric Datum of Australia (GDA94) based
on ITRF1992 reference frame at epoch 1994.0;
GRS80 Ellipsoid.
Grid Co-ordinates recognise as Universal
Transverse Mercator using GRS80 ellipsoid-
Map Grid of Australia (MGA94).
Table 4.1 Hierarchy of Internationally recognised reference systems applicable to Australia.
236 Information on International Astronomical Union and its related activities is available on-line, Internet http://www.iau.org/ (accessed December 1999) Further information on Union of Geodesy and Geophysics is available on-line, Internet http://www.obs-mip.fr/uggi/ (accessed December 1999) 237 Boucher C., Altamimi Z., 1996, ‘The ITRF and its relationship to GPS.’ GPS WORLD Magazine, Volume 7, Number 9, September 1996. Also available on-line, Internet http://lareg.ensg.ign.fr/ITRF/ITRF-GPS.html (accessed April 2000) 238Further information on this IERS service is available on-line, Internet http://hpiers.obspm.fr/ (accessed February 2000) 239 Further Information on GDA94 Specifications can be found at GeoScience Australia On-line Internet http://www.auslig.gov.au/geodesy/datums/gda.htm#specs (accessed Jan 2003)
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It is in line with these global infrastructures that medium and long time-series of
acquired knowledge about how regions behaviour that ultimately leads to better
modelling of the surface of the planet. Distributed from this statement is the
application of this knowledge towards geodetic networks and its relationship to
the reference datum. This section has laid a foundation towards knowledge about
geodetic frameworks operated at celestial, global and regional (Australian) scales.
This framework acknowledges stock and flow concepts along with improving
methods of analysis towards refining these frameworks to what they are today.240
4.4 Datums - Static or Dynamic?
Evidence is emerging that the earth’s fabric, which holds the monuments of the
cadastre, is in fact moving, be it very slowly, due to the effects of crustal
deformation, localised geological conditions and/ or tectonic motions.241 This is a
cultural change from the assumption that the earth’s fabric (and the monuments
contained on it) was fixed. Fences and building structures will 'creep' over a fixed
definition line as this slow 'creep' movement can amount to a very significant
movement over a time-scale period of several decades. To account for this
movement, cadastral boundaries should also move given the relationships
between the cadastral monuments and the available evidence found by the
surveyor.
In any discussion relating to geodetic GPS positioning, the geodetic datum
parameter requires investigation of its origin and definition. In essence, the datum
of a geodetic network is defined, as the basic or minimum parameters needed to
define the network in space or to position the network relative to a pre-determined
co-ordinate system. For example, with conventional geodetic measurements
horizontal directions and distances contribute internal measurements between 240 Cook J.S., 1999, Urban and Regional Economics Lecture 02 Notes PSB611 – Basic Stock and Flow Concepts in Economics, Queensland University of Technology. Available Intranet http://www.dbe.bee.qut.edu.au/people/cookjs/psb611/611/611lec02.htm (accessed Jan.2003) 241 Exampled by evidence of others including Dawson, J, 2002, ‘South West Seismic Zone 2002- GPS Analysis’, GPS data analysis of 300km by 200km area of South West of Western Australia, published online by Geoscience Australia GPS Geodetic Technical Reports http://www.ga.gov.au/geodesy/reports/gps/ (accessed July 2004). Also Davies, R.G., 1995, Analysis of the Effects of Terrestrial Network Design and Length of Observation Time on Global Positioning System Derived Positional Values. Master of Science in Civil Engineering Thesis, School of Engineering, California State University.
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network points and therefore can only really define the relative positions of points
in a network. On the other hand, the absolute co-ordinates of a network point are
external quantities where they are measured relative to a larger pre-defined co-
ordinate system.
Arguably, many practicing surveyors are not well exposed to the term “geodetic
network datum”. Although recent changes from AMG84 to MGA94 and a
promotion campaign by national and state surveying and mapping organisations
appear to have improved the situation considerably.242
From a practical perspective, surveyors took it for granted that some points in a
newly established network have to be known in order to compute the co-ordinates
of unknown points. This approach is largely instilled in the surveyors practice and
can be shown to be mutually supported, for instance, wherever a local horizontal
or vertical network of a certain order of accuracy is established to provide control
for a mapping or large construction project. These large projects often detail
requirements according to various specifications, including that the new network
be tied to a certain number of appropriately distributed existing geodetic control
points of a certain order of accuracy.
242 For example the promotion of GDA work of Intergovernmental Committee on Surveying and Mapping ICSM, on-line Internet http://www.anzlic.org.au/icsm/index.html (accessed Jan. 2000) and the Australian & New Zealand Land Information Council ANZLIC spatial information council, on-line Internet http://www.anzlic.org.au/ (accessed Jan. 2000). ALSO ICSM, 1999, Going Geocentric – Understanding Australia’s New Coordinates, Video media production -10 minutes duration, produced by Intergovernmental Committee on Surveying and Mapping, June.
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This generalised approach is borne from conferring to such documentation as:
• Federal Geodetic Control Subcommittee and GPS Interagency Advisory
Council FGCS “Bluebook” (USA); 243
• GPS guidelines for Cadastral Surveys (New Zealand);244
• Specifications for Geodetic Network Design (New Zealand);245
• Accuracy Standards for Geodetic Control Surveys (New Zealand); 246 and
• Standards and Practices for Control Surveys (SP1) intended for
Australia.247
This generalised approach is to keep the existing control point co-ordinates fixed
in the network adjustment and to inherently provide datum information (usually a
minimum of three points in agreement) for the newly established datum. From
this point on the surveyor would not have to deal further with the datum
translation problem.
For example, Hoogsteden et al (1997) discuss using a GPS option for urban
cadastral redefinition survey. They raise a critical point in the relationship
between GPS co-ordinate system and the local co-ordinate system. In New Zealand, surveys which may involve replacing cadastral boundary pegs require that surveyors relocate and verify a survey origin; such an origin consisting of at least three existing marks from a previous survey.248
243 Of particular use and background conceptualization to integration of spatial datasets is the research study by Epstein, E.F., and Duchesneau, T., 1984, The Value and Use of a Geodetic Reference System, by University of Maine April 1984. Federal Geodetic Control Subcommittee, variable date, Input Formats and Specifications of the National (USA)Geodetic Survey Data Base- the NGS "Bluebook", available online Internet http://www.ngs.noaa.gov/FGCS/BlueBook/ (accessed Nov. 1999) 244 Office of Surveyor-General (NZ), 1999, GPS Guidelines for Cadastral Surveys OSG Technical Report 11, July 1999, Land Information New Zealand, available on-line Internet http://www.linz.govt.nz/rcs/linz/6121/gps_guidelines_cadastral_surveys.pdf (accessed Jan. 2003) 245 Office of Surveyor-General (NZ), 2002, Specifications for Geodetic Network Design, Version 1.8, June 2002, Land Information New Zealand, available on-line Internet http://www.linz.govt.nz/rcs/linz/23733/spec4designv18.pdf (accessed Jan. 2003) 246 Office of Surveyor-General (NZ), 1998, Accuracy Standards for Geodetic Control Surveys OSG1: (1998) available on-line, Internet http://www.linz.govt.nz/services/surveysystem/ osgpublications/osg_std1.pdf (last accessed Feb. 2000) 247 ICSM, 1999, Standards and Practices for Control Surveys, SP1, version 1.3, Intergovernmental Committee on Surveying and Mapping, available on-line, Internet, http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (accessed Sept. 1999) ALSO ICSM, 2002, Standards and Practices for Control Surveys, SP1, version 1.5 May 2002, Intergovernmental Committee on Surveying and Mapping Australia available on-line, Internet, http://www.icsm.gov.au/icsm/publications/sp1/sp1.htm (accessed May 2003) 248 Hoogsteden C., Denys P., McDaid D., 1997, ‘Cadastral Surveys and the GPS option: Origin definition, time and cost comparisons for an urban cadastral survey.’ Trans Tasman Surveyor Vol. 1, No.2 July 1997 p.47.
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They later comment that only three marks are required by New Zealand regulation
to establish relationships. Thus when using GPS, establishing a survey origin actually has a dual purpose. Firstly, as with conventional surveys, it enables the relationship and reliability of the existing marks to be proved. However it also establishes the important relationship between the GPS coordinate system (WGS84) and the local coordinate system (NZGD49) – New Zealand Geodetic Datum 1949.249
They continue that greater care is required in establishing a sound relationship
between the GPS operating datum and the National datum, thus …….often the GPS approach of establishing an origin is markedly different to the conventional method. Basically, the conventional approach simply requires the measurement of the angle and two distances between three existing survey marks. These are then compared with the existing bearings and distances from the underlying survey to prove the relationship. However, since GPS is a 3-dimensional positioning system, great care is necessary to establish a sound WGS84-NZGD49 relationship.250
Recognition is occurring that the earth’s fabric is subject to gradual movements,
be they very slowly in the Australia region, due to the effects of crustal
deformation, localised geological conditions and/or tectonic motions. The ‘fixed’ assets of landowners are in fact not fixed. Buildings, fences and boundary marks are moving very slowly relative to each other and relative to the survey control system. One of the principle aims of the cadastre must be to protect the ownership and use of the land and the assets that are attached to the land. Therefore cadastral boundaries must also be allowed to move.251
Empirical observations using repeated measurements of cadastral monuments in
the predominantly blacksoil Valley floor Linthorpe study area, Darling Downs
region, indicate a trend that cadastral monuments do move over time, (decades)
mainly because of the dominant role given to cadastral monuments over
measurements. This empirical result is based on the somewhat tentative
assumption that the measurement technique is sound and of sufficient precision
and quality, and a highly stable geodetic network is available for comparison
against. However, the magnitude of this casual observation is only in the order of
a few millimetres to centimetres given the above assumptions and associated
unknown variables. Even allowing for attrition of survey marks and
monumentation over time, cadastral boundaries are usually redefined either by
249 Ibid., p.47. 250 Ibid., p.51. 251 Grant, D.B., 1995, ‘A Dynamic Datum for a Dynamic Cadastre,’ Trans-Tasman Surveyor, Vol.1, Number 1, December 1995, p. 23.
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agreement with surrounding existing boundary monuments or from adjacent
survey marks within a few kilometres in rural areas or a few hundred metres in
urban areas. Over these relatively short distances, the deformation is usually
insignificant (except adjacent to earthquake ruptures or land slippage areas) even
after periods of 100 years.
Grant (1995) draws many parallels in cadastral systems between New Zealand
and Australia operating under a Torrens Title approach, such that: .... the present cadastral system is very tolerant of earth deformation. The many survey monuments that result from the present regulations and the primary role assigned to monuments and observations, ensure that the “fixed” assets of landowners, witness marks and boundaries move together. This maintains high spatial definition while accommodating the dynamics of earth deformation. However distortions in the present datum make it difficult to generate accurate boundary coordinates.252
For public trust and confidence in the modern cadastral system, the cadastre is to
remain somewhat constant with the movements of the earth’s fabric requiring
monitoring. This can be realised through re-observation over time at certain
epochs to gather data for modelling these movements. Using consistent re-
observation techniques, it is possible to attain more accurate descriptions, since
the position is defined by all the survey measurements rather than being adjusted
to the original.
This re-observation activity can be achieved from two sources:
• Precise re-observation of the geodetic survey control of acceptable and
significant monumentation standards that underpins the cadastre;
• Re-observation with each cadastral survey associated with individual
marks.
Co-ordinates of a uniform global quality and precision would be suitable to
represent movements of the earth’s fabric through these re-observation
techniques. However, this is somewhat difficult to achieve for the practicing
surveyor as the precision limits of total station traversing techniques may be as
good as 20 millimetres plus 2 parts per million in a rural survey environment.
252 Ibid., p.23.
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From a practical basis, the field measurements would need to be in the order of
sub two centimetres or better in order to add significance to this re-observation
activity.
The derivation of these field measurements also assumes a stable permanency of
the so-called permanent survey marks (physical ground mark) in question. New
technology approaches, such as Trimble Virtual Reference Station (VRS), claim
to provide centimetre accuracy across the entire VRS network with reference
stations spaced at 50km to 70km for the RTK-VRS techniques.253 This technique
then places higher importance on the quality of description and permanency of the
local base-station reference variables.
In association with other professionals, it is technically possible to monitor
motion related to seismic activity. With precise measurement of deformation it
then becomes possible to emulate its effects upon the Queensland geodetic
network and hence the linked cadastre. The application of geodetic GPS
techniques (especially permanent continuous tracking base stations) has real
potential to provide a more complete foundation to addressing more fundamental
questions, such as - What are the driving mechanisms for deformation within a
plate boundary? Or alternatively within the Bowen Basin region of Qld? The
relationship to the testing of the hypothesis is the question of whether or not the
crustal stability, or localised geological movement models, within Australia such
that a dynamic datum needs to be adopted. This is explored in the next two
sections of this chapter.
In areas such as Tibet, the movement of crustal fragments has dimension of tens
to hundreds of millimetres, in directions oblique or orthogonal to the overall
direction of convergence between India and Asia. This phenomenon then poses a
larger question - How is the cadastre maintained over a long time-period in these
regions? Much knowledge and application can be learned from problems and
challenges encountered by countries such as Tibet and New Zealand.
253 Trimble Navigation Limited, 2001, Trimble Virtual Reference Station (VRS) brochure, Available on-line Internet http://trl.trimble.com/dscgi/ds.py/Get/File-11464/VRS_brochure.pdf (accessed Jan 2002). The VRS technical specifications also outline detailed system components and configurations, available on-line Internet http://trl.trimble.com/dscgi/ds.py/Get/File-11465/VRS_Spec_Sheet.pdf (accessed Jan. 2002)
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Geodetic challenges arose in New Zealand in the moderately deforming zones
along the Australian/ Pacific plate boundary. Before 2000, New Zealand had been
using the New Zealand Geodetic Datum 1949 (NZGD49).254 After some fifty
years relative deformation across the boundary had amounted to 2~3m (about half
a metre per decade) and was becoming increasing difficult to fully constrain
geodetic networks to the 1949 adjustment straddling the plate boundary.255
The New Zealand approaches to these challenges have explored three options in
terms of institutional business plans and risk management processes. These three
options are summarised below, thus:- Another high level decision which can be made regarding key characteristics of the new datum, is that of the management of the coordinate changes, either due to earth deformation, from improved survey information or a combination of the two. Option 1 - Static Datum Under this option, the new datum is defined by the coordinates of key geodetic stations. The coordinates of these stations are held fixed. NZGD49 is an example of a static datum with the 1st Order trig coordinates being defined in 1949 and subsequently held fixed. Option 2 - Semi-dynamic Datum Under this option, the datum is defined by its relationship to a dynamic global reference frame at a specified epoch. The datum definition is frozen at this epoch and does not include time dependencies. Coordinates at the reference epoch may change slightly on acceptance of new data in order to maintain the defined relationship between the datum as a whole and the global reference system. Such changes would primarily be as a result of improved accuracy. However, larger coordinate jumps may be required as a result of earthquakes or localised mark movement. Modelling of more uniform time dependencies may be applied during calculations in order to remove systematic errors due to earth deformation. This modelling would be based on a velocity model and would effectively be a time-dependent transformation. All results would be converted back to the reference epoch and expressed in terms of that epoch. Option 3 - Dynamic Datum Under this option, the datum is defined by its relationship not to a specific reference frame at a specific epoch but continuously to a dynamic global reference system such as the International Terrestrial Reference System (ITRS). Time dependencies are included in the definition such as station velocities, rates of change for transformation parameters, etc. Coordinates, velocities, transformation parameters, etc., change as required to ensure that the datum axes, and thus the coordinates of points, closely maintain their defined relationship to those of the global reference system.256
254 Land Information New Zealand, 2000, New Zealand Geodetic Datum 2000 - Fact Sheet Available on-line Internet http://www.linz.govt.nz/rcs/linz/pub/web/root/core/SurveySystem/GeodeticInfo/GeodeticDatums/nzgd2000factsheet/index.jsp (Accessed Dec 2002) 255 Office of Surveyor General (NZ), 1998, A Proposal for Geodetic Datum Development, OSG TR2.1, Land Information New Zealand, pp. 11-12. Available on-line Internet http://www.linz.govt.nz/rcs/linz/6133/osgtech2_0.pdf (accessed Dec 2002) 256 Office of Surveyor General (NZ), 1998, A Proposal for Geodetic Datum Development, OSG TR2.1, Land Information New Zealand, pp.15. Available on-line Internet http://www.linz.govt.nz/rcs/linz/6133/osgtech2_0.pdf (accessed Dec 2002)
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A review of these New Zealand proposals found that the greatest resistance to
change was the method of management for dynamic systems. The review of
theses proposals also found that the dynamic datum option would involve a high
level of complexity right from the start for managing co-ordinates.257 Serious
concern was raised such that it would increase the complexity required of the
automated system in order to generate those co-ordinates and would also
complicate the management of external spatial databases.258 Other issues of
concern in introducing a dynamic datum included increased risk to government in
the short term and additional costs associated with education and change of
existing land administration systems.
Consideration is required at the design stages of an MBSIS of how the geodetic
information layer and the cadastral information layer interact with change. A
system that can accommodate change by incorporating the latest information as
and when it becomes available with regular updates is obviously a value-adding
system. A system design that handles change on a regular basis whereby the
persons trained in performing the function can achieve it routinely. This is a
different management culture from the process of changing datums every 20 years
or so, whereby the institutions probably will not have the individuals who
acquired specialist knowledge for implementation from the last change process.
The divide between a dynamic and semi dynamic datum may narrow depending
on the frequency of the adjustment process. A semi dynamic datum that can
accommodate new information into the adjustment processes may take place on a
more regular basis when the criteria for undertaking the adjustment can be
justified through direct and indirect benefits to the wider community.
Northern regions of Papua New Guinea may be more suited to idealistic dynamic
datums where multiple plates converge and observed ground deformation rates are
deemed large in magnitude. The concept of local controlled datums also has
potential for implementation to these instability areas. A feasibility study into the
implementation of a dynamic geodetic datum in Papua New Guinea, based on 257 Ibid., p.37
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repeated high-precision GPS measurement campaigns, is currently being
researched and assessed through Australian National University.259
As various geological studies have shown, although Australia is influenced by
tectonic motion, it has been generally assumed that Australia is on a single
tectonic plate. The entirety of the country generally moves in unison, in one
general direction, in one general velocity, at the limits of measurement precision
currently available to determine this finding.260 This motion is described as the
slow and general deformation that is continuous in time as summarised in Table
4.2. This motion, although small in magnitude and slow in time, still has some
influence in distortion of the geodetic control network that underpins the cadastre.
From a study of the literature on the topic of dynamic cadastres, advocates discuss
that the benefits of a dynamic cadastre would go a long way towards resolving
problems where the original co-ordinates may be in error (assuming a full co-
ordinated cadastre), where boundary monuments have been misplaced or where a
previously accepted observation was in error. With a dynamic cadastre there is an
inherent allowance made for the movement of the earth’s fabric and therefore
allowing positions (represented by four dimensional co-ordinates) to change with
time.
Supplementary to previous investigation of the measurement-based multipurpose
cadastre, there is an improved opportunity for new geodetic measurements to be
merged into the existing geodetic database to provide better quality results, as and
when they become available and to extract statistical information on the
improvement or converse degradation of the geodetic network in a local region.
However, a changing datum on a monthly basis can cause mammoth confusion
when dealing with four-dimensional spatial information. It can create some level
258 Ibid., p.37 259 Stanaway R., 2002, Implementation of a Dynamic Geodetic Datum in Papua New Guinea – A Feasibility Study. Interim Report for Master of Philosphy study, School of Earth Sciences, Australian National University. Link to PNG Dynamic Geodetic Datum project page, Online Internet http://wwwrses.anu.edu.au/~rich/pngdatum.htm (April 2003) 260 This assertion is justified by the graphical analysis plots relating to absolute co-ordinate positions of the Australian Regional GPS Network.(An evolving document). Geoscience Australia, 2002, Australian Regional GPS Network (ARGN) Co-ordinate Time Series, Space Geodesy Analysis Centre, National Mapping Division. Available on-line Internet http://www.auslig.gov.au/geodesy/sgc/gps/pdf/austect.pdf (accessed March 2002)
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of complexity when attempting to merge spatial data from various times into a
coherent model of what is the best representation of reality. The introduction of a
dynamic datum into a large region, such as the whole of the state of Queensland
for geodetic and cadastral purposes would create many management problems and
further translation levels of complex operations to the existing approach or a
measurement-based approach.
It is suggested that at a practical and management culture level, a semi dynamic
datum would be useful in design considerations for land administration functions.
A land administration system that can accommodate change on a regular basis
with the simple aid of time-stamping of information/data would provide benefits
to the data acquirers and users of such a system. Change to a datum definition
should be considered whereby the benefits outweigh the action of not doing
anything at all.
An alternative management approach is to conduct periodic datum adjustments,
whereby the working datum is stable for a time-period (for example 4 to 7 years)
before a datum adjustment or re-alignment is proposed and introduced (possibly
on a local controlled area). This management approach has some similarities to
the change processes from AGD84 to GDA 94 introduced in year 2000. However,
the timing of such a change is dependent on global influences such as redefinition
of the ITRF and the offset relationship to a suitable datum in Australia.
Institutional knowledge of this change process can be effectively managed
through education and training of land administration staff and advice to users of
the spatial information. However, at a practical level, the greatest resistance will
be from staff and users unfamiliar with change management principles and/or the
perceived benefits.
Therefore, in consideration of adopting a measurement-based approach, a
dynamic datum cannot be justified for a whole of state implementation in terms of
the ideology of the pursuit of the most recent up-to-date datum information. It is
recommended that a periodic adjustment to the datum definition, a semi-dynamic
datum, with accepted and confident transformation parameters, would allow
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continuity with the current geodetic and cadastral approaches. With the large
capacity and speed driven computing technology available today, the calculating
processes of re-adjustment are not a major aspect when completed on a regular
basis. Any proposal for provision of a measurement-based survey information
system would be acceptable to a semi-dynamic reference datum.
4.4.1 Limitations of Model Precision
Millimetre and sub-millimetre measurements with GPS are currently difficult to
achieve for short observation sessions. Long time-series of GPS datasets
collected from continuously operating stable sites and meeting strict location and
site environs, such as those discussed by CORS monitoring system: station
selection criteria;261 and New Zealand GPS continuous tracking stations;262 can
provide a reliable scientific base for geodetic analysis.
Analyses of continuous measurements at this level are affected by intricate and
often not completely understood motions and influences, such as:
• the relationship between the celestial reference system and the International
Terrestrial Reference System (ITRS), such as the rotation of the earth
• a-priori co-ordinates of the sites
• tectonic plate motion model used to account for site velocities
• adapted geo-potential model for the earth’s gravity fields
• tidal influences and tidal loading of near-shore crustal mass
• solar radiation pressure
• post-glacial isostatic rebound
• global climate change
• atmospheric effects and modelling for GPS measurements
• GPS antenna variations and offsets from GPS satellite centre of mass
• polar motion.263
261 National Oceanic & Atmospheric Administration (NOAA), 1999, National Geodetic Survey CORS System: Station Selection Criteria, National Geodetic Survey Division. Available on-line Internet http://www.ngs.noaa.gov/CORS/ (accessed Sept. 2001) 262 Office of the Surveyor General (NZ), 2000, Specifications for the Installation of GPS Continuous Tracking Stations, Version 1.1, November 2000, Land Information New Zealand. Available on-line Internet http://www.linz.govt.nz/rcs/linz/6256/gps_installation.pdf (accessed Feb 2003) 263 This list is not exhaustive and is based on introduction and summary information from the works of Manning J., Govind R., Holland P., 1998, ‘The Monitoring Of National And Regional Geodetic Networks’, Proceedings of International Workshop in Advances in GPS Deformation Monitoring. Perth, Australia September, 1998; and Vanicek P. and Krakewsky
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Various geodetic quantities affected also by other phenomena with influencing
effects based on their modelling ability (predictable). Therefore, uncertainty
imposed by these various models of a situation do influence the ability of
surveyors to extract millimetre and sub-millimetre precision with this
measurement tool.
These global representative models reinforce the notion that the earth’s fabric is
dynamic in nature. Measurement sample points located within a recognised plate
region indicate that compression and expansion of the earth’s surface is occurring
at magnitudes far greater than first speculated twenty years ago. High precision
GPS technology is increasingly being utilised for continuous data collection
purposes to model regional deformation areas264. Other high precision geodetic
techniques (VLBI, DORIS, and SLR) are generally more expensive to establish
and maintain relative to high precision continuous tracking GPS data networks.
The Australian Regional GPS network is starting to produce increased knowledge
on compression and expansion of the earth’s surface with the production of data
analysis “trends” indicating absolute movement velocity for each monitoring
location.265
E.J., 1986, Geodesy: The Concepts -Second Edition, Elsevier Science Publishing Company, Amsterdam; New York: North-Holland, pp. 607-610; and Torge W.,1986, Geodesy, An Introduction, Published by de Gruyter, Translation from German by Christopher Jekeli. 264 A high initial capital expense in establishing regional GPS networks is the Japanese example GEONET, Geographical Survey Institute, Japan. Available on-line Internet http://mekira.gsi.go.jp/ENGLISH/index.html (accessed Oct 2001) 265 Geoscience Australia, 2002, Australian Regional GPS Network (ARGN) Co-ordinate Time Series, Space Geodesy Analysis Centre, National Mapping Division. Available on-line Internet http://www.auslig.gov.au/geodesy/sgc/gps/pdf/austect.pdf (accessed March 2002)
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Table 4.2: Derived summary details of selected continuous GPS monitoring stations in Australia. Note that only GPS stations with more than 2 years of data (most in the period from start 2000 to March 2002). Displacements and 2D vector distance are in units of millimetres. Solutions based on trend line over the period Start 1998 to March 2002. Co-ordinate values aligned to ITRF2000 with reference epoch 1 January 2000. Source data synthesised from Australian Regional GPS network (ARGN) Co-ordinate Time Series at March 20, 2002.266
Table 4.2 and Figure 4.3 provide some evidence of this motion and deformation
of the Australian continent with emphasis on the precision of the GPS derived
measurements. Of particular note is the 2D vector distance of the ARGN sites. It
would have been expected that these values would all be similar in magnitude
given the resolution of measurement uncertainty. However, it is strongly inferred
from the differential displacement evidence that deformation of the Australian
continent is not uniform. This analysis reveals that compression appears to be
occurring from Townsville across to Darwin and to a lesser extent Townsville to
Alice Springs. The derived summary data also indicates some apparent expansion
of landmass between Perth/ Yaragadee and stations in the ACT.
266 Ibid., p.1-25.
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Figure 4.3: Townsville ARGN Co-ordinate Time Series Graph January 1998 to March 2002. Note: to be considered with the notes from page one of the original source document.267 This is the only continuous ARGN station in QLD. Preliminary data analysis is being conducted by the author for the QUT GPS community base station using time-series techniques with AUSPOS positioning service. The results of such analysis attempt to replicate the trend indicators above for the continuous tracking GPS operation of the Townsville ARGN station.
267 Ibid., p.23.
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Of concern to Queensland is the lack of other continuous monitoring stations to
deduce technically detailed comparisons about likely deformation in this region.
The Townsville ARGN graph (Figure 4.3) has been included to demonstrate the
consistency of data with relatively small variation of the error bars at one-sigma
level and the trend indicator of displacement.
Figure 4.4: The author undertaking geodetic control survey - Karangi Dam, NSW. Survey used dual frequency geodetic GPS equipment utilizing a network approach and multiple geodetic instruments. 268
With very recent advances in measurement techniques and processes, it is now
becoming possible to observe to some precision how continental plates are
moving relative to each other and deforming internally within a plate region. This
relatively new body of information, commonly known as regional and global
geodynamics, enables a greater understanding of the dynamics of planet earth’s
processes, including the distribution of displacements, finite strain and various
parameters creating the cause and effect of strains responsible for natural earth
processes.
268 More information on this survey project and analysis of combined results can be found Harris M.W., 1998, 'GPS and The Karangi Dam', Proceedings of F.I.G. Commission 6 (Engineering Surveys) International Congress, Brighton, United Kingdom.
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The application of geodetic techniques to a cadastral survey measurement
function will undoubtingly add to the measurement precision of the task
performed by the field surveyor. It must be acknowledged that certain advantages
can be achieved given this high precision technique applied to an application
(cadastral surveying) not requiring such measurement accuracies as prescribed by
legislative criteria, such as Queensland Surveyor Regulations 1992.269 These
advantage characteristics are inclusive of such elements as one person operation,
automation of calculations in embedded software, the short occupation times
(dependent on technique), redundancy of observation data allowing predictive
modelling to observation data, and limited requirement of direct visibility between
measurement points or traverse connections.
Arguably, the cadastral survey approach in Qld could be simplified if it could be
assumed that the marks placed by the original surveyor remain in the exact
location where it has been stated they have been placed. This fundamental
assumption cannot be made due to influencing factors such as seismic activity in
the form of earthquakes, tectonic plate motions, and others.
Surveyors have the ability to note and measure these seismic or other deforming
activities through repeat observation techniques. However, it is how and what
surveyors do with this modern measurement data that will allow for inferences
and patterns in the data to be analysed. Also noteworthy is that the marks
themselves may be disturbed by more direct means, for example, local soil
characteristics causing the movement of marks, effects of earthmoving equipment
operating in near vicinity, information deterioration, and others. However, the
reinstatement process generally accommodates small changes in mark location
caused by local soil characteristics and surveyors assignment of weight on
particular evidence found on the ground.
4.5 Indicators of Surface Movement 269 Queensland Government, 1992, Queensland Surveyors Regulations 1992, can be accessed on-line Internet http://www.legislation.qld.gov.au/LEGISLTN/CURRENT/S/SurveyorsR92_05A.pdf (accessed December 2001) Note that
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The analysis of the spatial distribution of earthquake epicentres can provide
knowledge of regions likely to or potentially likely to be prone to surface
movements induced by seismic activity. However, seismic characteristics of both
magnitude and depth of energy release moment both impact on the observation of
surface movements encountered. The Queensland region contains areas of
differential movement induced partial by rapid seismic and slower aseismic
deformations. The following mapping graphics and modelling, focusing on the
Queensland region, graphically supports this argument.
Figure 4.5: Australian Regional Earthquake Hazard Map with enlarged view of Earthquake Hazard - Southern Queensland.270 The Gladstone to Harvey Bay region shows the increased risk of earthquake influences. A small band of increased risk of similar magnitude also exists between Mackay and Cairns (not indicated in this figure).271
The geo-hazard risk contour map (National Geoscience dataset), as selectively
shown in Figures 4.5, based on earthquake measurements taken from the AGSO
World Earthquake Database, owned by the Australian Seismological Centre of
AGSO. It shows the acceleration coefficient of a 10 percent chance of being
exceeded in the next 50 years. As an example, a value of 0.05 means that in any
50-year period, there is a 90% chance that the peak ground acceleration will not
exceed 0.05. Peak ground acceleration is a dimensionless coefficient of
acceleration used by civil engineers and structural designers to estimate forces on the electronic versions of legislation (including endnotes) on this site are not recognised as the official or authorised version of legislation. 270 Ibid., map graphic enlarged for southern Queensland. 271 Geoscience Australia, 1998, Geohazard Risk Contour Map (National Geoscience Dataset), Dataset No. 2393, Custodian: AGSO - Geoscience Australia, based on modelling and interpretations at nominal 1:1,000,000 scale. Metadata abstract available, September, 1998
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building structures. High values of this calculation represent higher risk areas of
earthquake occurrence and consideration at the design stage of structures and
foundations.272
According to the QUAKES organisation (Queensland University Advanced
Centre for Earthquakes Studies), Australia is seismically active and earthquakes pose a substantial risk as demonstrated by the deadly magnitude 5.6 Newcastle earthquake of 1989. When compared to plate margin regions such as California or Japan, the rate of earthquakes is lower, but relative to other intraplate regions, Australia's earthquake activity is moderate to high. The level of the earthquake hazard of Australia's more active regions is roughly comparable to that of well known seismic zones in central USA. This is around 5 to 10 times lower than in California measured in engineering terms (horizontal ground acceleration with 10% probability of exceedance in 50 years). The largest earthquake that can occur in Australia is not yet known but is expected to be above Richter Magnitude 7, roughly similar to large Californian earthquakes. For example, the 1988 Tennant Creek earthquake had a Richter magnitude around 6.9, slightly larger than the 1994 Northridge earthquake near Los Angeles (Mw=6.7) that resulted in $US 15 billion and cost 57 lives. Earthquakes offshore southeastern Australia have exceeded ML=7.273
The following map-figures illustrate a view of earthquake activity to the study
area of interest (Queensland). Higher risk is identified in the Bundaberg region.
The spatial distribution of recorded seismic activity is of importance towards the
design of geodetic networks for the purpose of future Zero-Order network design
criteria and the organisation of Local Controlled Areas based on partial seismic
activity and the relationship to median and major earth faults.
272 Ibid., derived from Metadata for the dataset.
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Figure 4.6: Queensland Earthquake map indicating events larger than Richter magnitude 2.0.274
Figure 4.6 demonstrates the spatial distribution of all recorded earthquakes
in Queensland and …. … shows above magnitude 2 earthquakes in Queensland for the period 1866 - June 2000. Most earthquakes shown on the map were recorded since 1977 when seismographs started to be installed around the State's large dams. From 1977 until 2000 when the Queensland seismic network ceased to function, the Queensland seismic network detected and located over 110 earthquakes per year
273 QUAKES, 2001, Earthquake activity and level of risk in Australia: Earthquake Information, QUAKES web-site information includes various models and earthquake maps useful to this study, accessed on-line-Internet http://quakes.earth.uq.edu.au/seis_maps/index.html (Accessed Sept. 2001) 274 Ibid.
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on average. A small fraction of these events were also located by the national seismic network of the Australian Geological Survey Organisation which involved around 3 instruments in Queensland compared to around 30 within the Queensland network managed by QUAKES. The earthquake maps give a rough indication of the level of the earthquake hazard within the region. However, comparison between different sub-areas based on the density of epicentres is not possible without analysis to account for the sparseness and variable density of the seismic network. Furthermore, the presence or absence of small or large earthquakes is not necessarily indicative of the future potential of a large earthquake due to the combined effect of network limitations and complexity of the earthquake process. The Queensland earthquake map shows that the State is seismically active and suggests the highest hazard region lies along the populated eastern coast and near offshore regions. The largest earthquakes on the map are the offshore Gladstone 1918 earthquake (Richter magnitude estimate of ML=6.3 based on felt area and ML=6.0 based on an instrumental recording), and the 1935 Gayndah earthquake (Richter magnitude ML=6.1). Earthquakes with the potential to cause serious damage or fatalities (ML > 5) have occurred on average about every 5 years during the last century with several near misses to the State's large population centres.275
Of concern to geodetic infrastructure is this occurrence of a ML>5 about every 5
years. The linear correlation of seismic activity should be noted as a comparison
to the foundation design-work of LCA boundaries model as depicted in the next
section.
The Bundaberg region contains a high level of seismic activity particularly
running through a belt just inland of Bundaberg spanning downwards from
Gladstone through Gayndah and beyond. The closest moderate sized recent
earthquake struck about 40km from Bundaberg in 1985 and had a Richter
magnitude of 3.1.276 During the production of this thesis, an earthquake event
occurred in the Brisbane area with Richter magnitude of 2.8 at latitude -27.384
longitude 152.983; approximately 5 kilometre depth below Samford valley region
north west of Brisbane, on 14th December 2002.277 Reports in local newspapers of
minor wall and ceiling cracking experienced and shaking of home fixtures
reportedly experienced by householders within the Samford Valley catchment.
The mapping graphics produced by QUAKES and subsequent scientific analysis
and geo-hazard identification have clearly shown that the Queensland region is
275 Ibid. 276 Ibid. 277 GeoScience Australia, 2003, Recent Earthquakes Monthly Report, Published by Australian Geological Survey Organisation. Available online Internet http://www.ga.gov.au/bin/listQuakes?month=12&year=2002 (accessed May 2003)
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not a stable environment (seismically speaking) with a reported moderate to high
earthquake risk in global terms.278 As previously outlined, Australia lies within
one of these outer crust lithospheric plates that are roughly only 100km in vertical
thickness. The movement of the lithospheric plates induces stresses in the crust
and causes mountains and fault creation both at plate margins and within plates.279
The Australian plate has been subjected to stresses over thousand of years with
the now visible mountain ranges formed and the present remanent stresses are
sufficient for earthquakes to occur.
278 QUAKES, 2001, Earthquake activity and level of risk in Australia: Earthquake Information, QUAKES web-site information includes various models and earthquake maps useful to this study, accessed on-line-Internet http://quakes.earth.uq.edu.au/seis_maps/index.html (Accessed Sept. 2001) 279 Skinner, BJ., Porter SC., Park, J., 2004, Dynamic Earth: An Introduction to Physical Geology, 5th Edition, John Wiley and Sons. Chapters 10 and 12.
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4.6 Concept of Local Controlled Areas (LCA)
The purpose of this section is to outline the conceptual nature of Local Controlled
Areas (LCA). This conceptual aspect has been refined through identification of
physiographic areas and loosely described geological regions across Queensland.
The model has not considered Local Government boundaries as these are
considered of an arbitrary administrative nature that does not well fit the design
criteria. The Queensland Government regional description was discounted due to
the poor geometrical relationship of the central and western regional area
depictions.
This LCA identification method has been influenced by the acknowledged work
of Japanese Geographical Survey Institute;280 various publications from FIG
Permanent committee on GPS Reference Networks,281 South California Integrated
GPS Network; 282 Geophysical research relating to Pacific plate boundary
deformation investigations;283 Neotectonics of the Adelaide region;284 the
Australian Geological Survey Organisation long term studies in the Flinders
ranges of South Australia.285
280 Geographical Survey Institute, 2001, ‘Crustal Deformation of Japan detected by GEONET’, paper available from Japanese Geographical Survey Institute. Available on-line Internet http://mekira.gsi.go.jp/ENGLISH/index.html (accessed Oct 2001) 281 For example Imakiire, T., Nakahori, Y., 2001, 'GPS Earth Observation Network (GEONET) of Japan', Proceeding of FIG Working Week International Conference: New Technology for a New Century, Session 11 - Permanent GPS Reference Networks, May, Seoul, Korea. Also available on-line Internet http://www.fig.net/figtree/pub/proceedings/korea/full-papers/session11/(accessed June 2001) 282 South California Integrated GPS Network, 2003, SCIGN main index website, links to various journal articles and analysis. Available online Internet http://scign.jpl.nasa.gov (accessed May 2003) 283 Beavan J., Tregoning P., Bevis M., Kato T., Meertens C., 2002, ‘Motion and Rigidity of the Pacific Plate and Implications for Plate Boundary Deformation’, Journal of Geophysical Research, Vol. 107, No. B10, 2261 ETG 19-1 to ETG19-15. Available online Internet http://rses.anu.edu.au/geodynamics/gps/papers/beavan02.pdf (accessed Feb 2003) 284 Sandiford, M., 2003, Neotectonics of South-eastern Australia: linking the quaternary faulting record with seismicity and in situ stress, Evolution and dynamics of the Australia Plate, Geological Society of Australia, special publication 22, pp.101-103. Available on-line Internet: http://jaeger.earthsci.unimelb.edu.au/msandinfo/Publications/Manuscripts/AJES/GSA_2003a.pdf 285 Geoscience Australia, 2003, GA Earthquake Hazard and Neotectonics Project, AUSGEO News No. 70, June 2003, pp. 30-33.
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The base map of Qld for practical estimates of potential linear alignments forming
extents of LCA in QLd has been influenced by the neotectonics mapping
approach by Bird (1999)286. Additional influence has been the combination of the
base map with Holmes (1986) physiographic regions of Qld.287
The concept of these LCAs may be useful as a building block within a larger
hierarchical information system. From a logistical point of view and as an aid to
data management, the division of the LCA boundaries can equally be based on
effective differential capability range of a permanent GPS base station or Virtual
Reference Station network coverage.288 Each lot on plan information is contained
within a parish that in turn is contained within a suburb in a local authority
administration area and in respective turn contributes to a LCA based on a
geological or physiographic region. The LCA can be considered as a separate
business unit that aggregates data to higher administration levels. This is a
territorial information hierarchy. Accuracy of cadastral information in one LCA
can be used as one management performance metric for benchmarking or
comparison to other LCAs. This territorial structure promotes management
statistics to measure improvement or decay within a manageable LCA region.289
Exploration of prior research into local controlled cadastral areas by Cook (1996)
contributes to the understandings of the changing nature of geo-parameters and
strengthening the cadastral linkage to geodetic modelling.
286 Bird, P., 1999, Thin-plate and thin-shell finite elements program for forward dynamic modelling of plate deformation and faulting, Computers and Geosciences Journal, Vol. 25, No. 4, pp.383-394. ALSO Guide to making a Dynamic NEOTECTONIC Modelling MAP with Shells online Internet http://element.ess.ucla.edu/guide/step_01.htm 287 Holmes, J.H., 1986, Queensland: A Geographical Interpretation, Royal Geographical Society of Australia, 4th Series, Vol.1, 1986, Boolarong Publications, Brisbane. Page20. 288 Trimble Navigation Limited, 2001, Trimble Virtual Reference Station (VRS), Available on-line Internet http://www.trimble.com/vrs.html (accessed Jan. 2002). Contains links to VRS technical specifications and marketing brochure. ALSO OF INTEREST TO THIS CONCEPT IS THE QLD VRS PILOT NETWORK Higgins, M.B., 2001, 'An Australian Pilot Project for a Real Time Kinematic GPS Network using the Virtual Reference Station Concept', Proceeding of FIG Working Week International Conference: New Technology for a New Century, Session 11 - Permanent GPS Reference Networks, May 2001, Seoul, Korea. Also available on-line Internet http://www.fig.net/figtree/pub/proceedings/korea/full-papers/session11/higgins.htm (accessed June 2001)
289 Rajabifard, A., Escobar, F., and Williamson, I.P., 2000. ‘Hierarchical Spatial Reasoning Applied to Spatial Data Infrastructures,’ Proceedings of MSIA National Conference, Sydney, Mapping Science Institute Australia, December 2000. Available on-line Internet http://www.geom.unimelb.edu.au/research/publications/IPW/4_00Rajab_MS.pdf (June 2002)
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GPS derived cadastral surveys can be an efficient measurement tool in boundary
surveys especially in developing countries where many new cadastral portions
and large area subdivisions develop. The concept of Local Controlled Area (LCA)
is introduced to set the scene whereby surveyors are applying a geodetic
technique to a cadastral application and to assist with the organization of survey
information based on a local area. This is of key complimentary benefit to the
Measurement Based Spatial Information System development in Chapter 3 and
the influence of co-ordinate collection technologies being explored.
Of early note are the comments by Dowson and Sheppard (1952) in which they
suggest: ….it is the points in the reference framework fixed on land throughout the territory concerned that constitute the indispensable links between
(a) the measurements made and recorded on paper, in field books, or plans etc, in the course of land survey and;
(b) the ground itself. It is only through the establishment and maintenance of those ground points, in enduring form and suitably distributed, that land parcels defined during the process of cadastral survey can be located again reliably and authoritatively at need…….. boundary beacons on erection should be tied in by appropriate measurements to the adjoining points on the original reference framework and become incorporated in it. It this way the boundary beacons are made to serve a wider public purpose.290
These comments presume that the earth’s fabric is fixed in time within the
mentioned reference framework. These boundary beacons could arguable be
replaced by a network of continuously operating GPS monitoring stations with
internal relative measurements to this local control network forming a local
reference framework. This local reference framework can also be analysed higher
up the hierarchy to the Australian Fiducial Network. With knowledge of global
monitoring at high precision levels captured in the past thirty years or so, the
scientific community are now able to better model and provide some
predictability (broadly speaking) to regional geodynamics.
The engineering surveying description of dynamic models sets context for
geodetic monitoring. Dynamic models are the most general and comprehensive
models because they aim to describe the reality of dynamic systems completely.
290 Dowson, Sir E., and Sheppard,V.L.O. (1952) Land Registration, Her Majestys’ Stationary Office London. Cited by Dale 1990, p.86.
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The movements and distortions of the object can be considered a function of both
load and time.291 This implies time varying stresses and time varying re-actions
such as the regional changes to a geodetic network before and after a rapid
seismic event.
In recent years engineering sciences have established a standardized mathematical description of the temporal behaviour of dynamic systems according to system theory. In the following the variants of dynamic systems are characterized:
• Dynamic (cause-response) systems: Changes of input signals release a time-dependent process of adaptation of the system with the consequence that the reaction of the output side is delayed: a dynamic system has a memory. This is the general case. Special cases can be distinguished with respect to the factor time. There are two kinds of dynamic systems:
(a) dynamic systems as such react as in the general case: the deformations as the output signal are a function of time and (varying) loads. The knowledge of the memory of the system is the basis for prediction;
(b) static systems can be seen as a special case of dynamic systems. They react immediately (without a memory) to the change of the causative forces: the new state is a state of equilibrium. The deformations are a function of changed loads only.
• Autonomous (free) systems are not subject to acting forces. These systems can nevertheless be in motion. There are two kinds of autonomous systems:
(c) kinematic systems are in motion; the motion can be described as a function of time;
(d) random walk systems are in motion, but the motion is random, a function of time cannot be established apriori.
Modeling a dynamic process is by far more comprehensive than modeling solely the deformation as the reaction of the object in space and time. The complexity of dynamic modeling makes the requirement of interdisciplinary cooperation obvious.292
Figure 4.7: Hierarchy of models in geodetic deformation analysis.293
291 For example, the author and associate supervisors involvement in ongoing high precision survey monitoring of McDonald dam, Noosa Shire, where various flood loads effect the spillway structure over time. (cause –response monitoring) 292 FIG, 2001, Models and Terminology for the Analysis of Geodetic Monitoring Observations: Publication No. 25. Official Report of the Ad-Hoc Committee of FIG Working Group 6.1 Published by The International Federation of Surveyors (FIG), February 2001, Frederiksberg, Denmark. Available on-line Internet http://www.fig.net/figtree/pub/figpub/pub25/figpub25.htm (accessed March 2002) 293 Ibid. figure 7.
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The central issue of insufficient geodetic control for such high precision
application is seen as a frustration to realise the benefits and advantages of
modern survey technology. The author agrees with Cook’s (1994) assertion that: In essence, the conventional approach to deriving digital land boundary information requires that public funds should be used to establish control surveys. These need a density of marking and a pre-ordained specification for precision that allows coordinates of all salient points to be established absolutely within a map projection and for an indefinite period into the future…. The fact is that it has been neither economically viable nor politically acceptable for control surveys to precede development surveys in the manner suggested by conventional thinking. Traditionally surveyors have blamed governments for short-sightedness in not allocating sufficient public funds for control survey purposes. The real problem seems to be that the economic arguments for public funding of geodetic control surveys are not entirely convincing. At the same time private control surveys are being performed by comparatively small firms and agencies on a fairly regular basis. They are being done to control the apportionment of measurement errors to acceptable limits and obtain the advantages of modern surveying technology. This private control survey information is not readily accepted into public records, and it therefore serves no broader public purpose. At the same time that frustration is felt over failure of government to supply funding for control surveys, the information from private control surveys is effectively jettisoned.294
Arguably, the introduction of the concept of Local Controlled Areas could
improve the organisation of the state of Queensland’s survey related information.
The organisation of that specialised information should be based around
recognised local areas or regions in a hierarchical manner. Surveyors have had
some exposure to this notion in the past (previously know as Proclaimed Survey
Areas) whereby these problem areas included special situations in which short to
medium term corrective action was undertaken to improve the integrity of the
cadastre. This previous process created certainty for all registered owners and
their successors in title as to the position of boundaries and their respective rights
in title.
The measurement-based spatial information system concept operating in a local
controlled area, as discussed in chapter three, could be seen as an organisational
enticement for private firms to be supported in submitting work of geodetic
measurements and cadastral-geodetic connections to ultimately improve the
integrity of the Queensland cadastre.
294 Cook, J.S., 1994, A Cybernetic Approach to Land Management Issues. Ph.D. Thesis. p.128.
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The logic of incorporating latest spatial measurement information and geodetic
control could be suitable to the following framework of control systems.
Celestial Reference Framework
International Terrestrial Reference Framework
System of Continential High Precision Geodetic Control (ie. AFN, CORS)
System of Regional and State Geodetic Control
(ie. Qld 100km and 500km network) Local Controlled Areas based on a
manageable size and within a recognized region
Special Local Controlled Areas at fringe regions between recognized
geological regions Cadastral Surveys
within each Local
Controlled Area
"As-Constructed"
surveys within Local Controlled
Area directly dependent on
the control and deemed
cadastral survey
independent
Subsidiary "As-
Constructed" surveys deemed cadastral survey
dependent
Cadastral Surveys
within each Local
Controlled Area
"As-Constructed"
surveys within Local Controlled
Area directly dependent on
the control and deemed
cadastral survey
independent
Subsidiary "As-
Constructed" surveys deemed cadastral survey
dependent
Table 4.3: LCA placement within hierarchical reference frameworks. The cadastral process would be simplified if it could be assumed that the marks
placed by the original surveyor remain in the exact location where it has been
recorded they had been placed. This fundamental assumption cannot be
definitively made due to influencing factors such as seismic activity, aseismic
activity, human interference and many others. Also noteworthy is that at the scale
of a local survey, the marks themselves may be disturbed by more direct means,
for example, local soil characteristics causing the movement of marks, effects of
earthmoving equipment operating in near vicinity, information deterioration, and
others. However, the reinstatement process (through weighting of evidence on the
ground) generally accommodates small changes in mark location caused by local
soil characteristics.
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The criteria for success and statistical indicators of success, as previously outlined
in section 3.2.2 and 3.2.3, are extremely useful as measures of a system’s
improvement. A centralised State Government organised section (geodetic
information section for example) can monitor and examine the relationships
between adjoining proposed LCAs and the AFN on the scale of regions and whole
of State (including marine interests) and feed information upwards to National
and International efforts of global monitoring and geodynamic studies.
From a geodetic perspective, the scientific community is gaining an increased
understanding of the geodynamics of the Australian mainland and its territories.
Rather than examining the relative accuracies of control points within a local
controlled area, it is perhaps of more importance to look at long time-series of
absolute positioning data.295 Associated with this analysis is how the precision
attributes with the absolute position of a point are improving over time.296
This analogy can also apply at the local controlled area level whereby the
precision of positions (relative to the AFN) associated with each monitored
control point within a local controlled area is improving with time (with highly
developed data analysis techniques).297 Of equal importance is the accuracy of the
cadastre relative to the one or two monitored control point within the LCA. This
improved knowledge is beginning to be realised with the GeoScience Australia
production of time series ARGN graphs depicting continental movement trends
and the improving associated standard errors.298
It is proposed that each LCA contain its own database of the contained geodetic
measurements and the cadastral links to the geodetic infrastructure. Very large
database sizes (the scale of all of Queensland) are often viewed as overwhelming
when dealing with routine inquiries. The notion is that an LCA forms a
manageable and workable size for spatial data and information technology
295 For example, refer to previous analysis table 4.2 296 For one example of this point, figure 4.3 indicates reducing error-bar magnitudes from 1998 to 2002 when examining the Townsville co-ordinate time series graph. 297 Bird, P. and Liu, Z., 2002, Finite element modelling of Neotectonics in New Zealand, Journal of Geophysical Research Vol. 107, p 2328. 298 See the recent graphs of Geoscience Australia, 2002, Australian Regional GPS Network (ARGN) Co-ordinate Time Series report, Space Geodesy Analysis Centre, National Mapping Division, February 2002, Geoscience Australia. Available on-line Internet http://www.auslig.gov.au/geodesy/sgc/gps/pdf/austect.pdf (accessed March 2002)
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management in a region. The local users of the MBSIS, with local memory of
events and problem areas, would work as a team to improve the business units
overall cadastral performance metric, namely error ellipses.299
The designs and ideas presented in the following optimised model with base
mapping layer have been synthesised and influenced from published literature on
the principles of geodetic network optimisation contained in Grafarend (1974);300
Cross (1985);301 Schmitt(1985);302 Schaffrin(1985);303 and Wells, et,al.(1986).304
A number of simulations and input design criteria have been explored, mapped,
reflected upon, refined and developed to obtain the following network map
covering QLD and its marine interests. The location of monitoring points are not
central within the LCA (in an ideal world) and the preferred location/ site
selection based on preliminary scan results and zero order network design analysis
of topographic mapping and state/commonwealth owned land holdings.
299 Refer to sample Linthorpe Valley DCDB with error ellipses after adjustment in figures 3.3 and 3.4. 300 Grafarend, E.W. ,1974, Optimisation of Geodetic Networks. Bolletino di Geodesia a Science Affini, 1974 Vol.33 No4 pp.351-406 Cited in Kuang, p.196. 301 Cross, P.A., 1985, ‘Numerical Methods in Network Designs,’ Optimisation and Design of Geodetic Networks, edited by Grafarend and Sanso. Springer:Berlin 1985 pp.429-435. QUTGP526.33 302 Schmitt G., 1985, ‘A review of network designs, criteria, risk functions and design ordering,’ Optimisation and Design of Geodetic Networks, edited by Grafarend and Sanso. Springer:Berlin 1985 pp.6-10. QUTGP526.33 303 Schaffrin B.,1985, ‘Aspects of network design,’ Optimisation and Design of Geodetic Networks, edited by Grafarend and Sanso. Springer:Berlin 1985 pp.548-597. 304 Wells, D., Langley, R., Vanicek, P., Craymer, M., 1986, "GPSNET" A Program for the Interactive Design of Geodetic GPS Networks, Contract Research Report for Geodetic Survey of Canada, 63 pages.
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Figure 4.8: Optimised Monitoring Network B based on 13 LCA. This monitoring network exhibits bias towards the population centres (east-coast fringe) with one primary monitoring station proposed per LCA. Model indicating optimised network for primary control location within LCA and the baseline geometry forming the network. Compiled base-map used for development of LCA models. Physiographic regions are also shown. Interpretations based on the composite works of Holmes;305 and AGSO.306 The only Fiducial Control mark (AFN) of the ARGN is shown near Townsville. 305 Holmes, J.H., 1986, Queensland: A Geographical Interpretation, Royal Geographical Society of Australia, 4th Series, Vol.1, 1986, Boolarong Publications, Brisbane. Page20. 306 Geoscience Australia, 2001, Online Maps: Geohazards, Geoscience Australia is the national agency for geoscience research and information. Department of Industry, Tourism and Resources. On-line access available http://www.agso.gov.au/map/ (accessed May 2001)
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Figure 4.9: Model of 200km usability zones from 13 monitoring sites. This refined model provides coverage to the population centres along the coastal fringe and development areas such as resources mining in central and north-west Qld. This model best suits the broad coverage goal for kinematic GPS techniques and static observation campaigns for densification of geodetic networks. This useability model also proves approximately 70% coverage of Qld marine interests. An additional investment of a Monitoring station near Weipa would provide around 92% coverage of marine interests, but negligible geodetic monitoring knowledge being on existing LCA.
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Useability aspects and modelling based on 500km static solutions and 200km
radius kinematic solutions have been examined and refined.307 This examination
has not included localised site-specific Real-Time Kinematic (RTK) techniques.
One major advantage of GPS infrastructure development is the multi-modal
aspect and provision of datasets to multiple users. These aspects have been
reviewed through the literature in part by the co-ordinated investment and
deployment of permanent GPS base station network (GPSnet) in Victoria.308 One
component of the Victorian geodetic strategy is the GPSnet, which can provide
centimetre accurate positions (depending on equipment and techniques used).
GPSnet can provide coverage to the entire Victorian state with an average base
station spacing of approximately 160km.309
Most use of GPS control is highly likely in population areas and anticipated
development regions. As such GPS networks can provide benefits to many users
in these developed population areas. A progressive rollout of infrastructure
approach aids the capital expenditure justification given government departmental
budgetary priorities and future project planning cycles (2-4 years). For example,
the pilot project of the VRS concept covers the rapid land development areas of
South-East Qld.310 This approach demonstrates similarity with the rollout of the
GPSnet infrastructure in Victoria.311
307 Based on manufacturers current recommended usage and range depending on GPS technique. Also Kirk G., 1999, ‘Guide to Successful GPS RTK Surveying,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited. pp.6. 308 Hale, M., and Mowlam, A., 2001, ‘Using the Victorian Cooperative GPS Base Station Network.’ Proceedings of 2001 - A Spatial Odyssey including 42nd Australian Surveyors Congress, p.2, Institution of Surveyors Australia, Brisbane Convention and Exhibition Centre. 309 Land Victoria, 2002, Information Pages on GPSnet and Geodetic Strategy. Department of Natural Resources and Environment, Victoria. Available on-line Internet http://www.land.vic.gov.au/gpsnet/ (accessed March 2002) 310 Higgins, M.B., 2001, 'An Australian Pilot Project for a Real Time Kinematic GPS Network using the Virtual Reference Station Concept', Proceeding of FIG Working Week International Conference: New Technology for a New Century, Session 11 - Permanent GPS Reference Networks, May, Seoul, Korea. Also available on-line Internet http://www.fig.net/figtree/pub/proceedings/korea/full-papers/session11/higgins.htm (accessed June 2001) 311 Hale, M., and Mowlam, A., 2001, ‘Using the Victorian Cooperative GPS Base Station Network.’ Proceedings of 2001 - A Spatial Odyssey including 42nd Australian Surveyors Congress, p.2, Institution of Surveyors Australia, Brisbane Convention and Exhibition Centre.
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4.7 Summary
This chapter has presented a two part discussion. The first part is an overview of
geodetic positioning and national and international geodetic level frameworks. It
has been shown that in the last decade, improved knowledge has been acquired as
to the dynamics of regions and globally, whereas a datum by its definition is a
standing representation at a point-in-time that models the dynamics of this planet.
The introduction of a dynamic datum into a local controlled area or state region
for geodetic and cadastral purposes would certainly create untold problems and
create a further complexity to operations of existing approach or a measurement-
based approach. An improved manageable approach is to conduct periodic datum
adjustments, whereby the working datum is stable for a time-period (for example
15 to 20 years) before a datum adjustment or re-alignment is undertaken.
The second part of the discussion was a review of seismic indicators of the earth’s
surface centred on the state of Queensland. A summary of the conceptual ideas of
Local Controlled Areas (LCA) was introduced that related to potential movement
characteristics and useability of previously classified rural land. Seismic
influences have been discussed and it is has been shown that the changing nature
of the earth’s fabric needs to be reflected in a well sampled geodetic network
underpinning the legal cadastre. This review has indicated that analysis of
monitoring station time-series in the ARGN are demonstrating the earth’s fabric
in Queensland are subject to periodic movements and should not be assumed as
fixed.
The cadastre of Queensland is a maturing and ever evolving systemically, both on
land and in maritime environments. GPS is bringing measurements that are more
accurate into the cadastre, but the current systems behind the processing of this
data can only make limited use of higher quality data being produced due to some
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inadequacies of the system.312 The system is seen as fulfilling the user
requirements as is, but with future technology developments, such as dual
positioning receivers (GPS/GLONASS) and pseudolite technology to name a few,
it could become the basis for a much greater range of integration applications
within the broader Australian spatial data infrastructure.
312 Inadequacies of Qld cadastral system have in part been studied by Steggall 2001. The concern is still the paper based cadastral plan within a digital IT environment. Steggall, S., 2001, Evolution of Digital Reinstatement Methods within Private Organisations, Master of Applied Science (Research) Thesis, Qld University of Technology, Brisbane.
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CHAPTER FIVE
GPS MEASUREMENT TECHNOLOGY ISSUES
With his marine clocks, John Harrison tested the waters of space-time. He succeeded, against
all odds, in using the fourth - temporal - dimension to link points on the three-
dimensional globe. He wrested the world's whereabouts from the stars, and locked the
secret in a pocket watch.313 5.1 Introduction Improved GPS survey techniques offer better ways of knowing where
something is located with increased precisions and smaller uncertainties. GPS
is becoming another scientific instrument in the modern surveyor’s toolbox.
The requirements of geodetic surveying are to ensure adequate redundancy and
reliable positional information. Survey quality GPS provides four-dimensional
reliable information, with abundant redundant data (dependant on the method
313 Sobel, D., 1995, Longitude,p.175, published by Fourth Estate Limited, London.
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utilised) without the traditional traversing requirements of intervisibility
between stations and designing of the network to give equilateral triangles.
Previous arguments highlighted that entities and features were once assumed
‘fixed’ are actually moving (be it very slowly) due to the macro-scale effects of
the earth’s crustal deformation or tectonic motion. Evidence of this is
becoming available through temporal studies involved with monitoring of
national geodetic networks.314
At the micro-scale, over a prolonged period of time, fences and buildings will
‘creep’ over coordinated, single-epoch boundaries. This slow movement can
amount to very significant amounts with temporal considerations. Cadastral
boundaries should also move with their spatial relatives to account for this slow
movement. For the cadastre to remain constant, it needs to move with the
regional ‘fabric’ of the earth.
This salient point reinforces the ‘monuments over measurements’ belief in
weighting strategies for the collection of cadastral evidence in boundary
reinstatement. This aspect is particularly relevant in the rural cadastre where
there are often long periods between successive surveys.
The cadastral reinstatement process can be simplified if it could be warranted
that the marks placed by the original surveyor remain in the exact location
where it has been recorded they had been placed. Obviously, this warranty
cannot be made without considerations of real-world variable factors.
Additionally, this simplified assumption cannot be made due to influencing
factors such as seismic and aseismic activity in the form of earthquakes,
tectonic plate motions, or the survey marks themselves being disturbed by
more direct means. For example, local soil characteristics causing the
314 Manning J., Govind R., Holland P., 1998, ‘The Monitoring Of National And Regional Geodetic Networks’, Proceedings of International Workshop in Advances in GPS Deformation Monitoring. Perth, Australia September, 1998. Also available on-line Internet http://www.auslig.gov.au/geodesy/techrpts/techrpts.htm (accessed December 2000) ALSO worthy to note is Office of Surveyor General (NZ), 2000, Specifications for the Installation of GPS Continuous Tracking Stations Version 1.1, November 2000, Land Information New Zealand. Available on-line Internet http://www.linz.govt.nz/rcs/linz/6256/gps_installation.pdf (accessed Feb 2003)
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movement of marks, effects of earthmoving equipment operating in near
vicinity, information deterioration, human interference through vandalism and
other influences.315
New knowledge, commonly known as regional and global geodynamics,
enables a greater understanding of the dynamics of planet earth processes. This
includes the distribution of displacements, point velocity vectors, finite strain
and various parameters creating the cause and effect of strains responsible for
natural earth processes.
5.2 Australian and International Framework relating to Measurement
The purpose of this section is to examine measurement traceability work
conducted overseas and how this may be realized in an Australian scene. It is
acknowledged that others have examined this issue in an Australian context.
The logical incremental step in this realization is that the term ‘position’ has
recently become a recognized value standard in Australia.316
The national measurement system is the infrastructure that ensures a consistent
and internationally recognised basis for measurement throughout Australia. The purpose of the national measurement system is to enable individuals and organisations to make measurements competently and accurately, to demonstrate the validity of such measurements and to coordinate Australia’s measurement system with the measurement systems of other countries. Australia is in the fortunate position of possessing a well-developed national measurement system. The system is made up of four national organisations which are complemented by trade measurement authorities and verifying authorities.317
315 See table 2.3 section 2.3.2 Issues of Integrity. 316 National Standards Commission (Australia), 2001, Determinations of Recognised-value Standards of Measurement, Other Publications:Determinations ,Sydney, NSW, August 2001 6pp. Available for download via Internet http://www.nsc.gov.au/PAGES/Info/info_sales_other.html (accessed December 2001) 317 National Standards Commission (Australia), 2002, Australia’s National Measurement System, Leaflet No 24, Sydney, NSW, February 2002 4pp. Available on-line internet, http://www.nsc.gov.au/PDF_WORD/Info/L24.doc (accessed March 2002)
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The national organisations are:
• the National Standards Commission responsible for legal metrology;318
• the Commonwealth Scientific and Research Organisation (CSIRO)
responsible for physical standards;319
• the National Association of Testing Authorities, Australia (NATA)
responsible for laboratory accreditation;320 and
• Standards Australia International Ltd responsible for standards
specifications.321
Also of special interest to spatial science professionals is the Commonwealth
Department of Transport and Regional Services (DOTARS),322 Australian
Global Navigation Satellite System Coordination Committee (AGCC).323
The AGCC have developed national strategic policy in terms of Satellite
navigation and application areas. Of additional interest to the arguments of
verification of GPS signals, the: Legal Issues Working Group (LWG) has investigated the way in which GPS position and time is derived and how it relates to the GPS data collected and processed by Geoscience Australia and to coordinated universal time (UTC) as measured by the CSIRO National Measurement Laboratory (NML) in Australia. The group investigated whether the data collected and the tracing of GPS time in this way was sufficient for the purposes of evidence in Australian courts for signal verification. The LWG concluded that the CSIRO NML and Geoscience Australia record and maintain sufficient data to support the accurate and reliable calculation of timing and position data, and that these records may provide appropriate evidence for the verification of GPS signals.324
318 National Standards Commision, 2003, NSC web site, on-line Internet http://www.nsc.goc.au (accessed March 2003) 319 CSIRO, 2003, National Measurement Laboratory Overview index page, Available on-line Internet http://www.nml.csiro.au/ (accessed March 2003) 320 National Association of Testing Authorities, 2003, NATA overview web site, on-line Internet http://www.nata.asn.au/ (accessed March 2003) 321 Standards Australia International Ltd, 2003, Standards Australia Overview web site, on-line Intenet http://www.standards.com.au/STANDARDS/INFO/SAIOVERVIEW/SAIOVERVIEW.HTM (accessed March 2003) 322 Commonwealth Department of Industry Tourism and Resources, 2003, National Measurement Institute web site, Available on-line Internet http://www.measurement.gov.au/index.cfm (accessed June 2003) 323 Commonwealth Department of Transport and Regional Services, 2003, Australian Global Navigation Satellite System Coordination Committee, index page, available online Internet http://www.agcc.gov.au/policy.htm (accessed May 2003) 324 Commonwealth Department of Transport and Regional Services, 2003, Verification of Timing and Signals index page, Australian Global Navigation Satellite System Coordination Committee, available online Internet http://www.agcc.gov.au/Verification.htm (accessed May 2003)
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The National Measurement Laboratory of CSIRO undertakes GPS integrity
monitoring, GPS time transfer functions and continual documentation.325
Much of the groundwork involved in quantifying and progressing the quality
“position” has been undertaken by the ICSM and the legal metrology section of
the National Standards Commission. This verification process has not yet been
realized through the verifying authority or the state government survey
authority nor legislative amendments (June 2003).
5.2.1 International Measurement System
The first arguable attempt to analyse and describe the concept of a
measurement system was made in 1967 by Dr Robert D Huntoon, a former
Director of the Institute for Basic Standards, the (US) National Bureau of
Standards (NBS).326 Dr Huntoon adopted a systems approach to examine the
components and structure of the measurement infrastructure in the United
States. He described the infrastructure as comprising two interacting systems,
namely: ..the conceptual and operational systems. The conceptual system is a rational, ordered structure of rules, definitions, laws, conventions, or procedures which provides the fundamental basis upon which the operational system can be built. The operational system is an ordered structure of functional elements – that is, organizations of people – interacting with one another under central guidance to perform a function. It is national in scope; it assumes a character suited to the nation it serves, and one that is consistent with the requirements of the conceptual system.327
The International System of Units (SI) is the realisation of this conceptual
system, which has been adopted internationally because of the international
agreement Convention of the Metre.328 This system provides a comprehensive
325 CSIRO, 2003, National Measurement Laboratory Overview index page, Available on-line Internet http://www.nml.csiro.au/ (accessed May 2003) Integrity monitoring can be found on-line Internet ftp://time1.tip.csiro.au/pub/timedata/gps/APMP_data/GPS_Integrity/ (accessed May 2003) 326 US National Bureau of Standards (NBS) was renamed in 1988 to the National Institute of Standards and Technology (NIST). Index web-site entry via Internet http://www.nist.gov (accessed June 2001) 327 Huntoon, R.D., 1967, ‘Concept of a National Measurement System,’ Science, vol.158, no.3797, October, pp.67-71 (Cited in Boey 1999, p.29) 328 Further information on the Convention of the Metre can be found through the BIPM site on-line Internet http://www.bipm.org/enus/1_Convention/ (accessed June 2001)
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set of rules and specifications for the definition and realisation of units of
measurements. The operational system is that part of the system that
implements the conceptual elements and is usually described as a country’s
national measurement infrastructure.329
The international measurement system of today is composed of four main
organizations, namely the General Conference on Weights and Measures
(Conference Generale des Poids et Mesures, CGPM), the International
Organisation of Legal Metrology (Organisation Internationale de Metrologie
Legale, OIML), the International Organisation for Standardization (ISO) and
the International Laboratory Accreditation Cooperation (ILAC).330 The origin
of the international measurement system can be attributed to the signing of the
Convention of the Metre (Convention du Metre). This convention is an
International treaty signed in 1875 by 17 countries in recognition of the
benefits to be derived from the universal adoption of a single, rational system
of units of measurement, particularly the metric system, based on the metre, the
second and the kilogram.331 The metric system has since matured into its
modern counterpart commonly known as the International System of Units
(Systeme International, SI).332 Some fifty-one nations, known as member
states, including Australia, conform to the international treaty.333
The international organisation responsible for the legal aspects of
measurements is the International Organization of Legal Metrology (OIML).
The OIML cooperates closely with the BIPM and has a general secretariat
329 For example: Federal Geodetic Control Subcommittee, Input Formats and Specifications of the National (USA) Geodetic Survey Data Base- the NGS "Bluebook", available online, Internet http://www.ngs.noaa.gov/FGCS/BlueBook/ (accessed Nov. 1999) AND National Oceanic & Atmospheric Administration (NOAA), 1999, National Geodetic Survey CORS System: Station Selection Criteria, National Geodetic Survey Division. Available on-line Internet http://www.ngs.noaa.gov/CORS/ (accessed Sept. 2001) 330 As at April 2003. 331 Further information on the Convention of the Metre can be found through the BIPM site on-line Internet http://www.bipm.org/enus/1_Convention/ (accessed June 2001) 332 Further information including definitions, historical context and international aspects of the Systeme International can be found through US National Institute of Standards and Technology (NIST) – on-line Internet http://physics.nist.gov/cuu/Units/ (accessed June 2001) 333 At April 2003.
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named the International Bureau of Legal Metrology (Bureau International de
Metrologie Legale, BIML).
Legal metrology is the entirety of the legislative, administrative and technical procedures established by, or by reference to public authorities, and implemented on their behalf in order to specify and to ensure, in a regulatory or contractual manner, the appropriate quality and credibility of measurements related to official controls, trade, health, safety and the environment.
The International Organization of Legal Metrology (OIML) was established in 1955 in order to promote the global harmonization of legal metrology procedures. Since that time, the OIML has developed a worldwide technical structure that provides its Members with metrological guidelines for the elaboration of national and regional requirements concerning the manufacture and use of measuring instruments for legal metrology applications.334
The BIPM is the focus of a network of scientific and technical linkages
between industrialised countries. Under the authority of the Convention of the
Metre, the BIPM is delegated with the task of warranting world-wide
uniformity of measurements and their traceability to the SI.
At a meeting held in Paris on 14 October 1999, the directors of the national metrology institutes (NMIs) of thirty-eight Member States of the Metre Convention and representatives of two international organizations signed a Mutual Recognition Arrangement (MRA) for national measurement standards and for calibration and measurement certificates issued by national metrology institutes.
This Mutual Recognition Arrangment[sic] is a response to a growing need for an open, transparent and comprehensive scheme to give users reliable quantitative information on the comparability of national metrology services and to provide the technical basis for wider agreements negotiated for international trade, commerce and regulatory affairs.335
This Mutual Recognition Arrangement (MRA) introduces the concept of
international equivalence of national measurement standards. Equivalence is a
term used to link measurements or standards at the same level. Unlike the
concept of traceability, there is minimal hierarchical relationship between
equivalent standards or measurements between organisations. The comparison
structure within a nation appears unchanged with the MRA focused on
334 OIML, 2001, Legal metrology and the OIML, Introductory information on International Legal Metrology, available on-line Internet http://www.oiml.org/oimlstructures/IntroductiontoOIML (accessed Nov 2001) 335 BIPM, 2001, Mutual Recognition Arrangement (MRA), JCRB and BIPM key comparison database, on-line summary document of the MRA, available http://www.bipm.org/enus/8_Key_Comparisons/key_comparisons.html (accessed June 2001). Further technical detail on the key comparisons is contained in the document by CIPM, March 1999, Guidelines for CIPM Key Comparisons, available on-line Internet http://www.bipm.org/pdf/guidelines.pdf (accessed June 2001)
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comparisons between nations. Key comparisons appear to be utilised as a
means to achieve equivalence of national measurement standards.
Whilst surveyors and other spatial science professionals often view metrology
as the specialisation of mechanical engineering disciplines, it is worthy to
accept an appreciation of the International and Australian efforts and linkages
to metrology and national standards generally.
It is important to gain an appreciation of these international efforts,
undertakings and guidelines in proposing a local (state level) comparison
method of a measurement technology. The recent issue of the concept of
equivalence and not the traditional hierarchical approach, as seen with EDM
traceability, is arguably noteworthy of further technical investigations at a local
level.
5.2.2 Australian Framework Relating to Measurement
Currently there is a requirement in most survey legislation for measurements of
length to be traceable to the National Primary Standard of length through
approved calibration methods.336 The National Measurement Act 1960, s.10
stipulates that measurements be required to be legally traceable if they are to
form the basis for litigation.337
For GPS derived positions to be traceable, the appropriate standards of
measurement must be identified and approved calibration/verification methods
must be developed. However, with the recent adoption of recognised-value
standard for position relative to the Australian Fiducial Network and
Geoscience Australia (formerly AUSLIG) being appointed as the verification
authority, there would be a need for ‘acceptable means’ to establishing the
336 Boey, S.S., and Parker, J.R.,1996, 'A review of current Australian survey legislation in the face of modern measuring technology.' The Australian Surveyor. Vol.41, no.4 December, pp.278-287. 337 Commonwealth of Australia, variable date, National Measurement Act 1960, Commonwealth Government Printer, Canberra. Section 10. An on-line copy of the Act and amendments may be view through http://scaleplus.law.gov.au/ (accessed October 2000)
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legal traceability of GPS derived positions.338 This will undoubtedly require
amendments to jurisdictional legislation relating to cadastral survey operations.
Particular to this point, relative positions principally derived from known and
accepted continuously monitored control position utilising differential carrier-
phase GPS methods requires recognition.
Rueger(1991) has principally undertaken previous research on this Australian
framework relating to distance measurements topic.339 Processes and
procedures for determining legally traceable measurements (pre GPS) have
been implemented in Australia to ensure measurements are what they
represent. These concepts are generally contained within s.10 of the National
Measurement Act 1960, which requires measurements used for legal purposes
to be made traceable to the appropriate national standards of measurements
through a hierarchy of comparisons and documentary evidence.340 The
comparison process examines standards of an increasingly higher order of
accuracy as demonstrated in figure 5.1.
338 National Standards Commission, 2003, Verifying Authorities for Reference Standards of Measurement, Information webpage, specifically the appointment of Geoscience Australia for the physical quantity: position. Online Internet http://www.nsc.gov.au/PAGES/Nms/nms_appointed.html#rsm (accessed June 2003) 339 Rueger, J.M. 1991, ‘Legal Calibration of Electronic Distance Meters in Australia’. The Australian Surveyor, Vol 36, No.3, Sept. 1991, pp.195-212. 340 This documentary evidence is outlined in the NSC Inspectors handbook – procedure no.10 for length measuring instruments, fixed or flexible, and applies to surveyors tapes and bands. National Standards Commission (Australia), 1990, Uniform Test Procedure for Length Measuring Instruments (Inspectors Handbook), First edition May 1990, 8pp. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/test_proc/tp_10.pdf (accessed December 2001)
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Figure 5.1: Australia’s hierarchy of physical units and standards.341
The national context of measurement comparisons and operational framework
has been examined. The Australian national measurement system is similar in
structure to overseas measurement systems. The national measurement system
is a coherent formal system that ensures that measurements can be made on a
consistent basis throughout the country. This system provides a reference for
physical measurements such that the quantitative data about a land parcel in
Tasmania, for example, is consistent with the quantitative data about a land
parcel in Torres Strait and visa-versa.
The current (May 2003) situation is that the Geoscience Australia (formerly
AUSLIG) organisation has just recently been appointed as a verifying authority
for reference standards of measurement for the physical quantity ‘position’.342
341 National Standards Commission, 2002, Australia’s National Measurement System, Leaflet No 24, February 2002 Available on-line internet, http://www.nsc.gov.au/PDF_WORD/Info/L24.doc (accessed March 2002) 342 National Standards Commission, 2003, Verifying Authorities for Reference Standards of Measurement, Information webpage, specifically the appointment of Geoscience Australia for the physical quantity: position. Online Internet http://www.nsc.gov.au/PAGES/Nms/nms_appointed.html#rsm (accessed June 2003) Also of interest is National Standards Commission, 2002, Conditions Relating to the Appointment of Verifying Authorities for Reference Standards of Measurement. 23 pages Available online Internet
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Australia has two principal methods of disseminating standards of
measurement to prove traceability to Australian primary standards of
measurement held and maintained by CSIRO’s National Measurement
Laboratory. One method is through the National Association of Testing
Authorities, Australia (NATA), and the other is through the appointment of
verifying authorities by the National Standards Commission.343
The Commission appoints verifying authorities under Regulation 77 of the Regulations in force under the Act. Verifying authorities are appointed where there is a need for legally traceable measurement, such as measurements that form the basis for government regulation, agreements, contracts and court proceedings.
A verifying authority is empowered to issue certificates under Regulation 13 that attest to the verification of a standard of measurement. Such a certificate is evidence of the matters stated in it and may be received as evidence in any court of law.
An increasing number of measurements are being made for regulatory purposes, and these require traceability within the meaning of section 10 of the Act, e.g. vehicle speed, breathalyser measurements and measurements for environmental monitoring. Many of the measurements are made by laboratories that have not been appointed as verifying authorities, but which may be able to demonstrate a chain of calibrations to Australian primary standards.
Advice from the Attorney General indicates that measurements from a particular laboratory, although being able to demonstrate a chain of calibrations, may not comply with section 10 of the Act, and could be excluded from legal proceedings on the basis of the hearsay rule of evidence. Certificates issued under Regulation 13 are always admissible as evidence in legal proceedings.344
In essence, the National Standard Commission appoints the verifying
authorities that hold standards of measurement for various physical quantities
for which there is a legal requirement to demonstrate the value and uncertainty
of the quantity that has been measured. The standards they hold must be legally
traceable to the Australian primary standards.345
http://www.nsc.gov.au/PDF_WORD/NMS/varsm_conds.doc (accessed June2003) 343 More specifically are the details contained in National Standards Commission (Australia), 2002, Conditions Relating to the Appointment of Verifying Authorities for Reference Standards of Measurement, National Standards Commission of Australia. 23 pages. Available online Internet http://www.nsc.gov.au/PDF_WORD/NMS/varsm_conds.doc (accessed June2003) 344 National Standards Commission (Australia), 2002, The National Measurement Act, NSC information leaflet no.25, Sydney, NSW. November 2002, page 5. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/L25.pdf (accessed May 2003) 345 For the quantity position, this is equivalent to the recognised value standard. National Standards Commission (Australia), 2002, Australian National Measurement System, NSC information leaflet no.24, Sydney, NSW, February 2002, page 4. Available online Internet http://www.nsc.gov.au/PDF_WORD/Info/L24.pdf (accessed May 2003)
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A critical extract from the NSC handbook relates to the term “verify” and the
use of the common term ‘certify’, such: This Verifying Authorities Handbook is intended for use by verifying authorities which are appointed under the provisions of Regulation 73 of the National Measurement Regulations 1999 (the Regulations) in accordance with the National Measurement Act 1960 (the Act) to verify reference standards of measurement under the provisions of Regulations 13, 30 and 31. Note that for the purposes of Commonwealth legislation the term ‘verify’ is employed, however the term ‘certify’ is commonly used in State and Territory legislation to describe an equivalent function.346
Of special interest to this dissertation is chapter eleven of the Verifying
Authorities Handbook outlining approved methods of verification of reference
standards of measurement for position. It is speculated that the GeoScience
Australia organisation will collect baseline data for these purposes prior to any
formal forthcoming statement on the matter.
In terms of the national measurement system, the Australian legal units of
measurement may be formed only for the physical quantities listed in the
National Measurement Guidelines (1999), of which position is the most recent.
Of particular policy interest is the note attached to the term “position”. Note Position is defined in terms of a group of 3 coordinates. The Australian Fiducial Network has been determined as a recognised-value standard of position by the Commission at the request of the Inter-Government Committee on Surveying Measurements.347
346 National Standards Commission, 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003, page iv. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003) 347 National Standards Commission (Australia), 1999, National Measurement Guidelines 1999, National Standards Commission,Sydney, NSW. Page 5. Available online Internet http://www.nsc.gov.au/PDF_WORD/NMS/Guidelines.pdf (accessed December 2001)
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5.3 Calibration and Traceability discussion associated with GPS derived Measurements
It could be argued that calibration is to determine the deviation from a
standard, and implies relating the measurements taken with an instrument to
that standard through a process known as the term “traceability”. Traceability
is required to be pre-defined and if it is to serve a legal purpose, made into law.
Traceability of a measurement can also be described as a process of
comparisons of a range of values from the normal working range presented by
the instrument that measures a physical quantity and assessed against the legal
Commonwealth standards for that physical quantity, as per the comparisons
approach made using EDMI on a calibrated pillar range.
GPS is a fundamentally different technology to Electronic Distance Measuring
Instruments (EDMI), however the calibration process for EDMI does not deal
with the technological intrinsic properties of the instrument but rather with
comparing the measurements obtained with the supposed instrument to some
appropriate standard.
The term “distance measuring devices” can be widely used to discuss such
instruments as a ruler, a tape, a thermometer, a micrometer, a scale. The
methods, reference standards and associated tools for calibrating distance-
measuring devices may be similar, which is not surprising as they are utilised
to measure the same magnitudes.348 The calibration process of a particular
instrument is similar in nature to looking for a deviation from a standard within
a confidence level or a degree of uncertainty associated with the measurement.
348This assertion is justifiable given the technical details associated various measuring device within National Standards Commission (Australia), 1990, Uniform Test Procedure for Length Measuring Instruments (Inspectors Handbook), First edition May 1990, Sydney, NSW, 8pp. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/test_proc/tp_10.pdf (accessed December 2001)
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The literature review relating to the GPS NAVigation Satellite Timing And
Ranging (NAVSTAR) system shows that the clock mechanism is the
fundamental source of the quality of time pulse signals and distances derived
by carrier phase measurements.349
Arguably, when one queries the derived length between two GPS receivers or
the positional measurement of a single GPS receiver, are you necessarily
asking about the accuracy (and quality) of the atomic clocks on the satellites
and the receivers being used? This line of questioning could be further
extended to the validity of Einstein’s theory of general relativity.350
The relative movements during signal transit time can be summarised,
assuming that the celestial movement of the Earth is fixed, by the following
useful theoretical example: Both the satellite clocks and receiver clocks experience error. The satellite clock corrections are transmitted to the receiver in the navigation message. The receiver clock errors are unknown, however. Therefore, we must model these errors and compute the corrections. ......Timing for GPS focuses on how long it takes a particular wave to travel between a satellite and a receiver, the transit time. ......The average transit time between a GPS satellite and receiver is about 80 milliseconds. During this time space, the earth rotates approximately 30 metres (this value varies with latitude). In that same amount of time, the satellite moves approximately 300 metres. Therefore, the computed transit time must also be corrected for earth rotation as well as the satellite’s motion. Luckily, GPS survey receivers compute their own clock errors using pseudoranges and include that information in the datafile. These stored receiver clock offsets are accurate to better than 2 nanoseconds. 351
The importance of the precise timing and the satellite clocks cannot be
overstated. They are “driven” by reference to atomic clocks at the United
States Naval Observatory that are tied directly to the SI second and Universal
349 United States Department of Defence, 2003, NAVSTAR Global Positioning System Joint Program Office, index page. Available on-line Internet http://gps.losangeles.af.mil/jpo/index.htm (accessed May 2003) 350 A biography of Albert Einsteins' life and a brief summary of his concepts of general relativity and tensor calculus. O'Connor J.J, and Robertson E.F., 2001 Available on-line Internet http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/General_relativity.html#38 and biography http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Einstein.html 351 Trimble Navigation Limited, 1994, GPS Surveying General Reference, chapter 2 pages 2-12 & 2-13, Survey & Mapping Division, 1994. This extract is used in the teaching of Advanced Geodesy unit, undergraduate surveying and postgraduate geomatics programs at QUT.
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Time.352 Therefore, the transit times of the satellite signal through the L1
wavelength to the receivers may be matched and converted to ranges in SI
metres in an ideal world.
Recently, the notion of a position has reached a recognised value standard in
Australia. This recognised value standard importantly has not been included in
a base or derived SI unit to date (March 2003). The key difficulty arises in that
the GPS signals are not in direct control by the user, nor is the ionosphere or
troposphere variable precisely modelled or predictable that the GPS signals
must transit for ultra-precise time transfer.
As such, numerous jurisdictions have recommended best practice guidelines to
cover the instrumentation that can be controlled by the user for a particular
application. The assertion is made that the professional surveyors’ approach
should be cautious and to validate the correct operation of the ground-based
GPS measurement instrumentation.
The performance and assessment functions below are recommended to spatial
science professionals utilising carrier phase GPS. These consolidated functions
are drawn from Australian, Canadian, United States, New Zealand and
Malaysia documents relating to comparisons and checking of GPS surveys. 353
352 Reference made to USNO time comparisons to SI second made to BIPM. On-line Internet http://www.tycho.USNO.NAVY.MIL/ (Accessed Nov. 1999; Feb. 2000; April 2000) and http://tycho.usno.navy.mil/master.html (accessed March 2003) 353 Further information can be found on this investigation on-line Internet http://www.gmat.unsw.edu.au/snap/work/cadastral_surveys.htm and also See,S., Kadir,M., Chia,W.T., Teng,C.B., & Rizos, C., 1999, 'Potential use of GPS for Cadastral Surveys in Malaysia.' Proceedings of 40th Australian & 6th South-East Asian Surveyors Congress, Fremantle, Australia, 30 October - 5 November, p.176-184.
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Recommended Performance and Assessment Summary Functions
A Perform GPS measuring using a zero baseline test to examine the
correct operation of the antenna and internal receivers performance
under an identical satellite geometry and radio reception
configuration.354
B Perform GPS measuring using a derived length comparison against an
approved EDM calibration baseline that has been shown to provide a
traceability link to a national standard.
C Perform GPS measuring over a special test network that includes at least
3 geodetic control points (four or more points provide a degree of
redundancy and consistency of the internal stability) with known three
dimensional position. This includes documented uncertainties of those
control point positions and with preferably several independent
connections to the Australian Fiducial Network (AFN) through the
Australian Regional GPS Network (ARGN).
D Examine and assess the integrity monitoring reports derived
from the continuous ARGN to ensure reasonable operation during the
testing performed at steps A,B,C and E and during subsequent field
surveying operations.
E Examine the traceability of GPS receiver time frequency through the
period of testing at steps A,B and C using an Australian authorised
metrological laboratory.
Table 5.1: Recommended performance and assessment summary functions for
testing of static GPS survey networks.
The above testing functions only apply to static and rapid-static GPS
observation techniques. This testing approach would require all functional
steps performed at regular intervals, perhaps annually. However, this approach
354 United States Department of Commerce, 2003, GPS Antenna Calibration resources, National Oceanic and Atmospheric Administration, National Geodetic Survey, Geosciences Research Division. Available online Internet http://www.ngs.noaa.gov/ANTCAL/ (accessed April 2003) ALSO noteworthy are the characteristics of GPS antenna test results contained in Mader, G.L., unknown date, GPS Antenna Calibration at the National Geodetic Survey, National Geodetic Survey, National Oceanic and Atmospheric Administration. 15pp. Available on-line internet http://www.ngs.noaa.gov/ANTCAL/Files/summary.pdf (accessed April 2003)
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fundamentally presumes that during the intervening field production period, the
GPS measurement hardware configuration will operate in a consistent and
reliable manner. This approach is in agreement with other measurement
instrumentation relating to the testing and certifying functions outlined in
National Measurement Guidelines 1999.355
Figure 5.2: The author undertaking geodetic GPS measurements for length comparison purposes on an annual basis at Coombabah EDM baseline range, 2002. In essence, the approach adopted from recommendation B and C above.
In the case of the GPS space segment, there is no basis for such presumption as
the transmission signals from the GPS Satellite is not in the direct control of
the users and can at times endure unpredicted system problems. As an example
of this point, the literature has reported the following rare and unusual
identified incidents:
355 National Standards Commission (Australia), 1999, National Measurement Guidelines 1999, National Standards Commission, Sydney, NSW. 10pp. Available online Internet http://www.nsc.gov.au/ PDF_WORD/NMS/Guidelines.pdf (accessed December 2001)
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• Unhealthy satellites and constellation status;356
• Increased ionospheric activity;357
• Intentional ground based military (or other) jamming and interference
including intentional local area signal exclusion.358
Three GPS verification methods currently adopted by several counties for
measurement testing purposes include:
• Electromagnetic Distance Measurement Calibration ranges /networks;
• Special test networks;
• The geodetic network.
Several countries have either adopted or recommended the use of special test
networks for the exclusive purposes of evaluating GPS measuring systems.
These special test networks are usually established with conventional geodetic-
precision survey techniques with the derived high-precision results used as the
basis of comparison. Published Australian results for the practical
implementation of special test networks for measurement equivalence
approaches have been investigated by Curtin University,359 and University of
New South Wales.360
356 Operated by the men and women of the 2d Space Operations Squadron (2 SOPS) at Schriever AFB, CO (formerly Falcon AFB), GPS is also the world's largest military satellite constellation. 2 SOPS has three missions: global navigation, time transfer, and nuclear detection. Status information available on-line Internet http://WWW.SCHRIEVER.AF.MIL/GPS/ (December 2001) Several incidents of behavioural anomalies, technical faults and out-of tolerance transmissions have been reported and documented. 357 Knight M., Finn A., Cervera M., Thomas D., 1999,‘The Performance of GPS in the Presence of Ionospheric Scintillations’, Session 8-Multipath and Ionosphere, Proceedings of 4th International Symposium on Satellite Navigation Technology & Applications, Brisbane-Australia. July 1999. This paper is useful in identifying unpredicted modelling in an Australian context. SEE ALSO Wang, Yue-jin,1999, ‘GPS-observed Ionospheric Disturbances around the Australian Region during Magnetic Storms in Early May 1998’, Session 8-Multipath and Ionosphere, Proceedings of 4th International Symposium on Satellite Navigation Technology & Applications, Brisbane-Australia. July 1999. 358 Finn, A., 1999, ‘The Vulnerability of GPS and Dependent System’, Session 3-Interference, 4th International Symposium on Satellite Navigation Technology & Applications, Brisbane-Australia. July 1999. 359 Featherstone, W.E., et.al., 2001, ‘Establishment of a GNSS Testing and Validation Facility in Perth, Western Australia’, Timepiece, Spring 2001, pp14-17. Paper first presented to the 5Th International Symposium on Satellite Navigation Technology and Applications (SatNav2001), Canberra, July 2001. 360 See,S., Kadir,M., Chia,W.T., Teng,C.B., & Rizos, C., 1999, 'Potential use of GPS for Cadastral Surveys in Malaysia.' Proceedings of 40th Australian & 6th South-East Asian Surveyors Congress, Fremantle, Institution of Surveyors Australia, 30 October - 5 November, p.176-184.
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Boey et.al. (1997) has previously examined several countries approach to GPS
verification networks: In the United States, the Federal Geodetic Control Committee (1986:1988) has established special test networks to provide GPS manufacturers with an opportunity to test and verify quoted accuracy specifications for their receiver hardware and software positioning systems. In Canada, Craymer (1990:1993) reports that Geodetic Survey of Canada, in cooperation with the provinces, have established several test networks, known as GPS validation networks or basenets, to validate the qualifications of potential contractors to perform GPS surveys. In Greece, Katsambaleos and Savvaiolis (1996) recommend the use of small calibration networks for the purposes of ensuring quality control for EDM devices and GPS receivers. Land Information of New Zealand (LINZ), formerly DSCI, has published two sets of guidelines recommending the use of the national geodetic network for verifying surveys performed with GPS. (Specifically) cadastral surveys performed using GPS are required to connect to at least three geodetic central points in order to verify the reliability of origin marks. (DSLI 1994:6) GPS surveys that are to be added to the national control framework may be required to prove receiver hardware, field procedures and processing through a system test, which entails connecting surveys to at least four geodetic control points(DSLI 1996:7).361
Recent changes at international levels in adopting the concept of equivalence,
the notion of measurement standardisation with comparative models and the
Australian status of recognised value standard of position, have culminated in a
need to examine the issue at the surveying practice level. Arguably, the notion
of gaining confidence in measurements over a special test network for
comparison purposes by competent operators and employing suitable data
analysis methods and techniques is gaining justifiable support from many in
the industry, both locally and overseas.
With a recognised value standard for position formally recognised by the
National Standards Commission (NSC), the spatial sciences industry awaits the
NSC appointed responsible organisation (Geoscience Australia), for suitable
and acceptable procedures and techniques to allow for verification of the
361Boey S., Gerdan G., and Talbot N., 1997, ‘Verification Methods for Establishing Legally Traceable GPS Measurements in Australia’. Proceedings of 1st Trans Tasman Surveyors Conference, Newcastle, N.S.W. April 1997 page 17.5.
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quantity “position”.362 The recently published NSC Verifying Authorities
Handbook details requirements and required documentation and data formats
for a verifying authority to issue certification under Regulation 13.363 Policy
issues of the broader Global Navigation Satellite System in Australia is guided
by the Commonwealth Department of Transport and Regional Services, Australian
Global Navigation Satellite System Coordination Committee.364
Without pre-empting the methods and procedures of the verification authority
(Geoscience Australia), it is obvious that, with improving GPS measurement
systems entering the market-place, measuring systems require verification
and/or comparison to three-dimensional and four-dimensional rigorous results
and documented uncertainties. These measuring systems may include radio
links, wireless communication technologies, psuedolite and other augmentation
technology, virtual reference station technology and other evolving
technologies. From a traditional total station approach, this has been achieved
through comparison to fixed pillars with forced centring using calibrated EDM
baselines. It would appear that special test networks incorporating a
combination of EDM baselines and parts of the geodetic network would satisfy
the verification and/or comparison requirements of results obtained by the
hardware, software and trained operator. An examination of relevant and recent
literature in New Zealand and Canada supports this argument.365
362 It should be noted that the NSC verifying authorities handbook has just been published at the very conclusion of this research thesis. As such details of what a verifying authorithy may or may not provide in terms of documentation and other legal traceability issues has not been explored in the time available. 363 National Standards Commission (Australia), 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003, page iv. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003) 364Commonwealth Department of Transport and Regional Services, 2003, Australian Global Navigation Satellite System Coordination Committee, index page, National Strategic Policy for GNSS available online Internet http://www.agcc.gov.au/policy.htm (accessed May 2003) 365 Office of Surveyor-General (NZ), 1999, GPS Guidelines for Cadastral Surveys - OSG Technical Report 11, July 1999, Land Information New Zealand, available on-line Internet http://www.linz.govt.nz/rcs/linz/6121/gps_guidelines_cadastral_surveys.pdf (accessed Jan. 2003) See Also Federal Geodetic Control Subcommittee,1984, The Value and Use of a Geodetic Reference System, Research Study by University of Maine, April pp.46. Available online, Internet http://www.ngs.noaa.gov/FGCS/tech_pub/UseandValue.pdf (accessed Oct. 1999) Londe M., 1998, ‘Guidelines for using GPS on Large Scale Cadastral Surveys (Wyoming & Nebraska)’, Proceedings of 1998 Trimble User Conference. Trimble Navigation Limited. pp.4.
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This discussion gains support with the recent efforts and results of researchers
at Curtin University, Western Australia,366 in establishing a Global Navigation
Satellite System (GNSS) testing and validation facility.367 An aspect of that
facility is that the users are requested to conduct the GPS survey in a
production mode ensuring a faithfully replication of the procedures that are
likely to be used in survey practice. Another unusual aspect is the mixed
monuments approach incorporated into the survey testing design. One part of
the test facility uses permanent forced-centring pillars connected geodetically
to an EDM calibration range. The other part of the test facility uses a
combination of standard survey marks of the Western Australia geodetic
network, some of the fixed pillars, and some other ground marks. This
approach allows validation of the user to place the measurement system
antennas accurately and vertically over the ground marks.
In consideration of the arguments above, it is highly likely that the broad
spatial sciences industry will see amendments made to specific land surveying
legislation. Amended legislation adopting the principles of position verification
applied to the conduct of cadastral surveys may occur in the near future. These
amendments will most probably include concepts of positional and local
uncertainty associated with reporting of positions in a consistent manner.368
366 Featherstone, W.E., et.al., 2001, ‘Establishment of a GNSS Testing and Validation Facility in Perth, Western Australia’, Timepiece, Spring 2001, pp14-17. Paper first presented to the 5Th International Symposium on Satellite Navigation Technology and Applications (SatNav2001), Canberra, July 2001. 367 Commonwealth Department of Transport and Regional Services, 2003, Australian Global Navigation Satellite System Coordination Committee, index page, available online Internet http://www.agcc.gov.au/index.htm (accessed May 2003) 368 ICSM, 2002, Standards and Practices for Control Surveys, SP1 Australia version 1.5, available on-line, Internet, http://www.icsm.gov.au/icsm/publications/sp1/sp1.htm (accessed Dec. 2002) variable pp. New section on positional uncertainty.
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5.4 Timing Issues associated with GPS Instrumentation
Surveyors have previously used and gained familiarity with the UTC time
correction service for positional astronomy and sun observations for cadastral
work. This linkage of the time variable has identical linkage to GPS time
comparison (with the appropriate fixed offset) back to the SI second. This issue
was examined in some detail in a previously published paper with relevance to
the impending year 2000 problem, and the UTC and GPS time offset, insertion
of leap seconds and associated variance.369
Lombardi (1999) summarises the traceability question often required in society
for low accuracy timing measurement in a logical manner where the acceptable
uncertainties may be as large as parts per hundred. For example, the mechanical and electronic timers found in parking meters, coin operated laundries, car washes, taxicab meters and other devices where customers pay for “time” require traceability, but the acceptable uncertainty may be 5% or higher. These devices are calibrated with field standard stopwatches or interval timers with an acceptable uncertainty of about 2x10 (-4). Law enforcement agencies use tuning forks to calibrate radar equipment used to measure vehicle speed. Maintained traceability within 1x10(-3) is adequate for measuring speed within 0.1km/h.370
Accordingly, from the ISO definition relating to traceability, that the
traceability is the property of “the result of a measurement”.371 The magnitude
of the uncertainty quantity can vary widely depending upon the GPS receiver
used to perform the measurement along with the procedure used to perform the
measurement. In support of this line of inquiry, recent research findings discuss
the similarities and differences of the commercially available GPS models.372
369 Webb, R.M., 1999, ‘Surveyors and the Year 2000: Scare Mongering or Opportunity for Change’. The Queensland Surveyor. Journal of the Institution of Surveyors Australia, Queensland Division Vol. 1999, No.5 pp.46-52. 370 U.S. Dept. of Transportation, 1980, ‘Police Traffic Radar Issue Paper’,National Highway Traffic Safety Administration, Dept. Of Transportation HS-805 254, February 1980 (by way of Lombardi 1999, p.36) ALSO Young, W.L., Legal Calibration (Certification) of Police Traffic Control Devices (RADAR, LASER, VASCAR), Proceedings National Conference Standards Laboratory, 1998, pp199-201. (By way of Lombardi 1999, p.36) 371 International Organization for Standardization (ISO), 2000, What is ISO and Why are International Standards needed? Available on-line Internet http://www.iso.ch/iso/en/aboutiso/introduction/index.html (Accessed December 2000) 372 Lombardi M.A., 2000, ‘Using a Global Positioning System (GPS) receiver as a NIST traceable frequency standard’, National Institute of Standards and Technology (NIST), Time and Frequency Division, Boulder, United States. June 2000. Publication available on-line Internet http://www.boulder.nist.gov/timefreq/service/gpscal.htm (accessed Sept 2000) ALSO Recent research in remote calibration processes using GPS time transfer is summarised in Lombardi M.A., 2002, NIST Time and Frequency Services, NIST Special Publication 432, January 2002. pages 69-70. Available
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The following section is of importance to GPS measurement technology,
applied by surveyors and others, and more specifically to survey quality GPS
hardware. One of the foundation issues to this argument is the quality of the
instrumentation’s timing oscillator. A review of available survey quality
geodetic GPS instrumentation has shown that some are equipped with
reasonably stable timing oscillator technology.
Table 5.2: Summary of time and frequency links used to establish traceability to UTC (modified from Lombardi 1999).373 on-line Internet http://www.boulder.nist.gov/timefreq/general/pdf/1383.pdf (accessed April 2002) ALSO Lombardi M.A., Nelson L.M., Novick A.N., Zhang V.S., 2001, ‘Time and Frequency Measurements using the Global Positioning System (GPS), CAL-LAB’, The International Journal of Metrology, July-September 2001, pages 26-33. Available on-line Internet http://www.boulder.nist.gov/timefreq/general/pdf/1424.pdf (accessed April 2002) 373 Lombardi, M.A., 1999,’ Traceability in Time and Frequency Metrology’, National Institute of Standards and Technology, Time and Frequency Division, Boulder United States. October 1999. On-line publication available Internet http://www.boulder.nist.gov/timefreq/ service/publications.htm (accessed July 2000)., modified from p.37.
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Following on from the central argument is the quality issue of the
instrumentation’s timing oscillator. The following technical points further the
timing characteristics argument of high-end GPS receivers. This includes
survey quality units used by surveyors throughout Australia for survey control
networks. Most GPS receivers have poor short-term stability. The models with the best short-term stability typically discipline an oven controlled quartz oscillator (OCXO) or a rubidium oscillator to the GPS signal. However many receivers do not discipline an oscillator at all. Instead they divide the output of a small temperature controlled crystal oscillator (TCXO) to 1pps, and then synchronize the 1pps to the GPS signal. The TCXO free runs and the receiver accumulates time errors until the total time error approaches a threshold (a multiple of the half period of the oscillator), and then generates a phase step that reduces the time error to a minimum. Some receivers step phase in increments of 100 nanoseconds or less, but some use increments of 1 µs or larger. If the TCXO is offset in frequency by 1x10(-7) (typical), a 100nanosecond phase correction is needed every second. The short-term stability of these models is very poor, but their long term performance may be equivalent to models that discipline a quartz or rubidium. ...... since the deactivation of the Selective Availability program on May 2, 2000, most GPS receivers now produce a 1pps output with a standard deviation of 10nanoseconds or less. This is still enough noise to cause the short term (stability) of a GPS receiver to be poor, but the long-term stability is usually excellent. Many receivers produce frequency with an uncertainty of <1x10(-12) when averaged for one day. Two key factors that contribute to receiver performance are the quality of the receiver’s internal oscillator, and the quality of the software algorithms that process data acquired from the satellites.374
A direct performance comparison of timing information could be made
possible through the continuously operating GPS network operated by
Geoscience Australia known as ARGN.375 The United States NIST- Time and
Frequency Division have implemented the practical transfer notion of remote
calibration using automated Internet technology. 376 Creating a linkage using
automated Internet communication and appropriate software to allow an
individual geodetic survey-quality GPS receiver to make timing comparisons
374 Lombardi M.A., 2000, Using a Global Positioning System (GPS) receiver as a NIST traceable frequency standard, On-line Internet Article June 2000. Http://www.boulder.nist.gov/timefreq/service/gpscal.htm (accessed Sept 2000) 375 GeoScience Australia , 2002, Australian Regional GPS Network, ARGN Internet web-page entry point, on-line Internet http://www.auslig.gov.au/geodesy/argn/ (accessed April 2002) 376NIST Frequency Measurement & Analysis Service, available online internet http://www.boulder.nist.gov/timefreq/service/fms.htm (accessed June 2003) See also Ehrlich C.D., and Raspberry S.D., 1998, 'Metrological Timelines in Traceability', NIST Journal of Research, vol. 103, no. 1, January-February 1998. Available online Internet http://www.boulder.nist.gov/timefreq/service/fms.htm (accessed August 2000)
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(a typical minimum may be 6 hours of continuous data in parallel to the
AUSPOS on-line GPS processing) with the ARGN would be extremely useful
in adding value for survey practitioners in undertaking documented timing
comparisons.377 This avenue would require further technical and detailed
research on timing transfer techniques and potential direct use of or
collaboration with United States NIST- Time and Frequency Division using
Internet communications as part of the linkage into The Australian National
Time System.378
Boeys’ (1999) work also postulated an appropriate and practical means for
establishing the legal traceability of GPS measurements through the adoption
of time as the fundamental physical quantity. He proposed a model showing
the potential manner in which GPS measurements are traceable to UTC in a
direct manner. Lombardi (2000) and others have also supported this pathway in
attempts to include GPS time as a recognised reference source. GPST
measurement model directly contributes to this issue, such:
In [the figure below], the transfer of units to the working level GPS measurements is direct. The satellite atomic clocks, used to define GPST, are used to generate timed signals for GPS measurements. In other words, GPS measurements are determined directly from a standard of measurement. This approach obviates the need to establish a relationship with a standard through the conventional hierarchical comparison method. In order to ensure the accurate measurements of time in GPS, the performance of the satellite and receiver clocks must be acceptable. In the normal course of operation, the satellite and receiver clocks perform to very high standards. Normal clock errors can be effectively eliminated by observation differencing, particularly in the double differenced solution. Satellite positions, broadcast as satellite ephemerides, of acceptable tolerance are required for the determination of accurate receiver coordinates. …... The term effectively is used as a qualification, since some residual errors, as a result of differencing, will be present; however, their magnitude is insignificant, in view of the relatively low accuracy requirements of cadastral surveying, which are unlikely to be better than 50ppm.379
377 Further information of this new GPS resource can be found in the overview paper by Dawson, J., et.al., 2001, 'The AUSLIG Online GPS Processing System', Proceedings of 2001 - A Spatial Odyssey including 42nd Australian Surveyors Congress, pp.11, Institution of Surveyors Australia, Brisbane Convention and Exhibition Centre. On-line Internet access to the resource http://www.auslig.gov.au/geodesy/sgc/wwwgps/ (Acessed Nov. 2002) 378 This timing infrastructure could exist within the current national time-transfer framework as demonstrated by the diagram on page 9 of National Standards Commission (Australia), 1995b, The Australian National Time System, NSC information leaflet no.8, Sydney, NSW, April, 10pp. 379 Further discussion on regional GPS integrity monitoring for accurate timing is discussed pages 147 to 149 of Boey, S.S., 1999, A Model for Establishing the Legal Traceability of GPS Measurements for Cadastral Surveying in
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Figure 5.3: A potential model developed by Boey (1999) for traceability of GPST measurements.380
To improve GPS aspects of integrity, accuracy and availability, system
designers and researchers have enhanced operations in many ways. These
augmentation avenues include broadcast differential GPS, combined GPS and
GLONASS operations, integrated inertial measurement systems, and proposed
Wide Area Augment Systems (WAAS). However, ground-based positioning
transmitters had been used in marine applications up to the early 1990s, around
the same time that the GPS constellation reached maturity. Prior to the wide
scale adoption of GPS alone positioning in the late 1980s, other radio-based
positioning systems dominated the positioning market. Systems such as
Omega, Loran, Hifix or Mini-ranger systems were often used in the 1970s and
1980s for hydrographic survey applications.381 GPS positioning is unmatched
in its cost effectiveness, geographical coverage, accuracy and reliability in
normal operational regimes.
Australia, UNISURV Report, S-55, November 1999, School of Geomatic Engineering - University of New South Wales. 380 Ibid., p.148 381 The author has been involved in hydrographic survey operations using mini-ranger and hifix positioning solutions in the late 1980s.
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The concept of augmentation systems is not overly new but the innovation lies
in the integration of multiple positioning inputs into the fundamental position
plus time solution. A growing focus of research innovation is to supplement
conventional GPS with ground-based transmitters, called pseudo-satellites.
Pseudo-satellites have been quickly shortened to the general term pseudolites. A pseudolite transmits a signal with code-phase, carrier phase and data components with the same timing as the satellite signals and with nearly the same format. A GPS receiver acquires this signal and derives code-phase, pseudo-ranges or carrier-phase measurements to be used in a navigation algorithm. The major differences are that a pseudolite typically does not contain a high accuracy atomic clock and that the pseudolite position must be described in geographic terms rather than in orbital elements!382
Increasing complexity of measuring systems using augmentation methods must
require valid testing and calibration of all variables (including precise time) to
achieve quantification of inherent systemic errors and conditional criteria. A
performance test over known geometric lengths and configuration is strongly
recommended in the previous section. This recommendation is equally
applicable to a measurement system incorporating pseudolite technology. It is
further acknowledged that the precise measurement of pseudolite components
is beyond the scope of almost all surveyors and more aligned with the field of
metrology and electronic system engineering.
Recent and rapid advances in applications of pseudolite technology can be
found through rigorous research work conducted at Stanford University.383
Applied research into pseudolite technology includes a particular interest in
integrity monitoring of local area augmentation systems using pseudolite and
other technologies;384 indoor navigation systems;385 wide and local area
382 Cobb S. and O’Connor M., 1998, ‘Pseudolites Enhancing GPS with Ground-based Transmitters', GPSWORLD, July 1998, pp. 55. Published by Avanstar Communications. Available on-line internet http://www.Gpsworld.com/columns/0398/column/0398column.html (accessed September 2000) 383Stone J., LeMaster E., Powell J., Rock S., 1999, ‘GPS Pseudolite Transceivers and their Applications’, Proceedings of ION National Technical Meeting 1999, San Diego, CA. Authors from Department of Aeronautics and Astronautics, Stanford University. Available on-line Internet http://einstein.stanford.edu/gps/ABS/gps_pl_apps_jms_1999.html (accessed December 2001) ALSO of interest is the arguable world leader in pseudolite design and construction, The GPS Laboratory is in the Department of Aeronautics and Astronautics, Stanford University. Online Internet access http://www.stanford.edu/group/GPS/ (accessed November 2001) 384 LeMaster E., Matsuoka M., Rock S., 2002, Field Demonstration of a Mars Navigation System Utilizing GPS Pseudolite Transceivers. Proceedings of IEEE Position, Location, and Navigation Symposium, Palm Springs, CA, April 2002. Available on-line Internet http://sun-valley.stanford.edu/papers/LeMasterMR:2002.pdf (accessed June 2002)
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augmentation systems;386 and to deformation monitoring in mine-site
applications.387
The International GPS Service (IGS) and the Bureau International des Poids et
Mesures (BIPM) have established a joint pilot project for time and frequency
comparisons using GPS.388 The goal of this pilot project is to investigate the
use of GPS phase and code measurements to improve worldwide availability of
accurate time and frequency, including timing calibrations to the scientific
community.
Figure 5.4: Direct spatial connection to the Zero-order AFN.389 This approach is suggested by the National Standards Commission through the Verifying Authorities Handbook.
385 Cobb, S., 1997, GPS Pseudolites: Theory, Design, and Applications, PhD Doctoral Dissertation, Department of Aeronautics and Astronautics, Stanford University, 1997. Available online Internet http://waas.stanford.edu/~wwu/papers/gps/PDF/stuthesis.pdf (accessed Dec. 2002) ALSO Enge, P., Fan, Tiwari, Chou, Mann, Sahai, Stone, Van Roy, 2001, ‘Improving GPS Coverage and Continuity: Indoors and Downtown,’ Proceedings of Sep 2001 Institute of Navigation's GPS Conference, Salt Lake City, Utah. Available online Internet http://waas.stanford.edu/~wwu/papers/gps/PDF/engion01.pdf (accessed Dec. 2002) 386 Mitelman, A., Phelts, R.E., Akos, D., Pullen, S. and Enge, P., 2000, ‘A Real-Time Signal Quality Monitor for GPS Augmentation Systems,’ Proceedings of Sept 2000 Institute of Navigation's GPS conference, Salt Lake City, Utah. Available online Internet http://waas.stanford.edu/~wwu/papers/gps/PDF/sashaion00.pdf (accessed Jan. 2003) 387 Dai L., Wang J., Rizos C., Han S., 2002. ‘Pseudo-satellite applications in deformation monitoring’. GPS Solutions, Vol. 5 no. 3, pp80-87. Available on-line Internet http://www.gmat.unsw.edu.au/snap/publications/dai_etal2001b.pdf (accessed May 2002) 388 Ray, J., and E.F. Arias, 2001, IGS/BIPM Pilot Project to study time and frequency comparisons using GPS phase and code measurements, Interim Report to the 15th meeting of the consultative Committee for Time and Frequency (CCTF), at BIPM, Sèvres, France, 20-22 June 2001. Report also available on-line Internet http://maia.usno.navy.mil/gpst/refs/cctf01-a.doc (accessed March 2002) 389 National Standards Commission (Australia), 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003, page 66. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003)
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During the next few years it is highly likely fiducial timing facilities will be co-
established with the Australian Fiducial GPS network and other stations
forming the ARGN.390 Surveyors would determine not only relative
positioning to a nearby station within the ARGN, but also precise time
comparisons with documented uncertainties for their work. This functionality
will allow more rigorous precision of time-keeping in accordance with the
recommendations of the Interim Report to the 15th meeting of the Consultative
Committee for Time and Frequency (CCTF).391 This co-establishment facility
will offer broad benefits to the scientific community and if easily accessible via
internet access, the elusive GPS time comparison solutions will be more
enabled for the survey/spatial data-gathering practitioner.
390 This timing infrastructure has already started to be added to ARGN primary sites GeoScience Australia , 2002, Australian Regional GPS Network, ARGN Internet web-page entry point, on-line Internet http://www.auslig.gov.au/geodesy/argn/ (accessed Feb. 2003) 391 Ray, J., and E.F. Arias, 2001, IGS/BIPM Pilot Project to study time and frequency comparisons using GPS phase and code measurements, Interim Report to the 15th meeting of the consultative Committee for Time and Frequency (CCTF), at BIPM, Sèvres, France, 20-22 June 2001. Report also available on-line Internet http://maia.usno.navy.mil/gpst/refs/cctf01-a.doc (accessed March 2002)
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5.5 Legal Acceptance of Measurements
The following arguments and literature review of legal findings focus on the
central argument that for a challenge in a civil court action about a boundary
dispute derived from GPS measurements, that the GPS measurements
themselves are not legally traceable is accompanied by a burden of proof that
the measurements are not accurate. This section is included because of its
inherit relevance to the dissertation hypothesis and the application of scientific
measurements covered by state, territory and federal legislations relating to
land measurements.
A summary of rules of evidence and presumption of accuracy is expressly
included to set the background context before introducing material from an
“appeals” process about geographic position. The literature review process
undertaken for this section of the thesis (1998, end 2000 and early 2003) found
very little reporting in Australia of direct use or legal questioning of GPS
instrumentation (or derivations of the same technology). Overseas cases from
New Zealand, Canada and Italy have been reviewed but considered
contextually removed from the Australian land administration system.
Horlin (2000) has previously challenged the statements made by Boey and
Talbot (1996),392 and provides sufficient argument to the presumption of
accuracy for trustworthy scientific instruments.393 The selected reporting of
findings in the case Chinn Yaou Fa v Morris (1987) 87 FLR 36 Supreme Court
of Western Australia - Court of Appeal, is of particular relevance to surveyors
and highlights the relatively new legal precedent of the accuracy of a satellite
navigator used to determine the position of the vessel at the relevant time.394
392 Boey,S.S, and Talbot,N.C., 1996, ‘GPS for Cadastral Surveys - a position paper prepared for the Surveyors Board of Victoria’, presented at the 1996 Conference of the Reciprocating Surveyors Boards of Australia and New Zealand. (By way of Horlin 2000). 393 Horlin, Eric, 2000, ‘GPS- Presumed Accurate Until Proved Guilty,’ The Queensland Surveyor, vol.2000, no.1 February, pp.41-46.
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The research and critical opinions expressed by Horlin (2000) are included as it
provides a logical structure from a legalistic viewpoint towards the issue of
traceability of GPS measurements.395 His assertions relating to other
measurement instruments are supported by selected reported findings.
However, not all of these are include in this dissertation, but instead focus on
the issues most relevant to GPS instrumentation and the notion of proof related
to the term ‘position’ at a given point in time.
5.5.1 Rules of Evidence
Horlin (2000) speculates that most of the misinformation about legal
traceability and cadastral surveys seems related to ignorance of the rules of
evidence, especially rules associated with the burden of proof and the standard
of proof requirements.396 In criminal proceedings the burden of proof, sometimes referred to as the onus of proof, generally rest with the prosecution and should never shift. In almost all civil actions the party who has the legal onus also has the evidential onus.397
Horlin (2000) comments on the important distinction of the standard of proof
and includes critical opinions on the very limited reporting of such issues,
such: In criminal proceedings (including prosecutions of statutory offences) the standard is "beyond reasonable doubt" which is very high (say in the order of 85% or more) whilst in civil actions the standard of proof is "on the balance of probabilities" which is considerably lower standard (nominally 51% or higher). Boey and Hill (1995) quote Harvey of the National Standards Commission as describing the phrase 'for any legal purpose' in Section 10n of the National Measurement Act 1960 (Cth) as referring to:-
…situations in which the validity of measurements is likely to be challenged in a court of law. 398
394 Access to cases and decisions of the Supreme Court of Western Australia - Court of Appeal is available on-line Internet http://www.austlii.edu.au/au/cases/wa/WASCA/ (accessed November 2001) 395 Edited as necessary from Horlins’ (1999) original work in Timepeace. 396 Horlin, E., 2000, GPS- Presumed Accurate Until Proved Guilty, The Queensland Surveyor, vol.2000, no.1 February, pp.41-46. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter Spring 1999 397 Waight,P.K., and Williams,C.R., 1985, Cases and Materials on Evidence. Second Edition. The Law Book Company, Australia. (Cited by Horlin 2000) 398 Boey, S.S., and Hill, C.D., 1995, 'Can GPS measurements be legally used for cadastral surveying?' The Australian Surveyor, Vol.40, no. 2, pp.101-111
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Boey and Talbot stated:-
Legal traceability of measurements is required by the National Measurement Act 1960 in situations where the measurements may be challenged in the court of law ie. The measurements must be proven beyond reasonable doubt that they are what they purport to be.399
The standard of proof to which the statements above refer can clearly only
apply in criminal proceedings. This is clearly outside of the normal cadastral
surveying activities associated with land administration function, except for
maybe extra-ordinary arguments associated with criminal trespass.
Horlin (2000) continues the debate, thus:
The Harvey statement and the words [-] measurements may be challenged when used in isolation [-] ignore the imposition of the onus of proof (of the facts) associated with such a challenge. Such statements are only appropriate for criminal proceedings and even then the burden of proof may still rest with the party making the challenge. A challenge in a civil action, such as a boundary dispute, that GPS measurements are not legally traceable is accompanied by a burden of proof that the measurements are in fact inaccurate.
In Pearce v Dennis [1997] QCA 239 Supreme Court of Queensland - Court of
Appeal, dealing with evidence of an alcohol breathalyser instrument, the court
stated that:- The fact that at the hearing of a charge under s.16(1) the breathalyser or breath analysis instrument used to produce a certificate under s.16A(15D) and (15G) [under Traffic Act 1949] is not proved to have been calibrated using equipment verified or authenticated under the National Measurement Act 1960 (Cth.) does not serve to discharge the onus resting on a defendant under s.16A(15H) of proving that that instrument was either defective or not properly operated. To establish that some form of testing for accuracy has not been carried out is not to prove that the instrument in question is defective or not being operated properly. It simply means that there is no evidence at all on those matters. In the absence of affirmative evidence of defect or improper operation, the defendant fails to discharge the onus imposed by s.16A(15H).400
399 Boey,S.S, and Talbot,N.C., 1996, ‘GPS for Cadastral Surveys - a position paper prepared for the Surveyors Board of Victoria’, presented at the 1996 Conference of the Reciprocating Surveyors Boards of Australia and New Zealand. (Cited by way of Horlin 2000). Horlin, E., 2000, GPS- Presumed Accurate Until Proved Guilty, The Queensland Surveyor, vol.2000, no.1 February, page 42. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter Spring 1999 400 Supreme Court of Queensland - Court of Appeal, 1997, Pearce v Dennis [1997] QCA 239, 8th August 1997, Appeal No. 229 of 1997. Available on-line Internet http://www.austlii.edu.au/au/cases/qld/QCA/ (accessed May 2003)
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The standard of proof and the associated probabilities is an important critical
distinction depending on the nature of a dispute, be it related to criminal
proceedings or in civil actions. The natural progression of this argument is to
review the presumption of accuracy of scientific instruments.
5.5.2 Notion of a Presumption of Accuracy Horlin (2000) continues this interesting line of argument with the active
assertions and supporting justifications, such that: At common law the readings of scientific or technical instruments are prima facie evidence of the facts which they purport to register; this rule is sometimes referred to as the presumption of accuracy of scientific instruments. When an instrument is relied on for the first time evidence will normally be required as to its nature and function in order to persuade the court of its reliability (See Chiou Yaou Fa v Morris, infra).401
After some time the experience and confidence of the courts will be such that this evidence may be dispensed with and courts will take judicial notice of such instruments.402
This so-called presumption applies to instruments that are part of the:-
…class of instruments of a scientific or technical character which by general experience are known to be trustworthy, and are so notorious that the court requires no evidence to the effect that they do fall into such a class before allowing the presumption in question to operate with regard to the readings made thereon.
Per herring, CJ in Porter -v- Kolodziej [1962]VR 75.
Instruments that have been held to fall in that class include:- • a clock, Gorham -v- Brice [1902] 18 TLR 42-1: • a speedometer, Peterson -v- Holmes [1927] SASR 419: • a thermometer, Thompson -v- Kovacs [1959] VR 229: • a pair of scales, Giles -v- Dodds [1947] VLR 465: • a loadometer, Cheatle -v- Considine [1965] SASR 231: • an amphometer, Zappia –v- Webb [1974] WAR 15: and • a parking meter, Circo –v- Carmine unreported case, WA Supreme
Court Lib No. 98(X)961.
401 Ibid. p43. 402 Byrne, D. and Heydon,L.D., 1991, Cross on Evidence. Fourth Australian edition. Butterworths. Australia. (Cited by way of Horlin 2000).
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In Breedon –v- Kongras (1996) 16 WAR 66 the court held that a 'sheridan gauge' used to measure rock lobsters was not a scientific or technical instrument and the presumption didn't apply.403
However according to Horlin (2000), Justice White, in Mehesz –v- Redman
[1980] 26 SASR 244 White J., abstracted the following principles from the
case law :- 1. If the instrument falls within the class of instrument known as notorious
scientific instruments, the court will take judicial notice of its accuracy, so that the operator merely proves that he handled it properly and read it properly on the particular occasion.
2. If the instrument is not a notorious scientific instrument, its accuracy can be established by evidence: (a) that the instrument is within a class of instrument generally accepted by experts as accurate for its particular purpose:
(b) that the instrument, if handled properly, does produce accurate results:
(c) that the particular instrument was handled properly and read accurately by the operator on the particular occasion:
(a) and (b) must be established by expert testimony, that is, by experts with sufficient knowledge of that kind of instrument: and upon proof of (a) and (b), a latent presumption of accuracy arises which allows the court to infer accuracy on the particular occasion if it is proved. (c) can be established by a trained and competent person familiar with the operation of the instrument, not necessarily the type of expert who proves (a) and (b).
3. Where the actual accuracy of the measurement can be inferred from all
of the proved circumstances, it is not necessary to rely upon the presumption arising from (a) and (b), proof of which is superfluous.
He also stated in obiter:-
Quite apart from the questions of expense and delay in the administration of justice, the Court is entitled to rely upon evidence of measurements made by instruments which reputable scientists accept as accurate, whether those scientists have direct knowledge of the reasons for the instrument's accuracy or not, provided they have knowledge that the instrument's measurements are accurate according to a known standard, or are accepted as accurate by reputable scientists.404
Justice White’s comments reflect the foundation requirements for expert
witness testimony relating to instruments measurements and related accuracy.
403 Horlin, E., 2000, GPS- Presumed Accurate Until Proved Guilty, The Queensland Surveyor, vol.2000, no.1 February, page 42. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter, Spring 1999. 404 Supreme Court of South Australia, 1980, Mehesz v Redman , 26 SASR 244, White J., Available on-line Internet http://www.austlii.edu.au/au/cases/sa/ (Feb. 2003) Also reported by Horlin, E., 2000, ‘GPS- Presumed Accurate Until
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Horlin’s original work continues on to present selected relevant reported cases
relating to trade measurement devices. These other reported cases dealing with
qualifying accurate measurements from scientific instruments are not presented
here, however the situation can be summarised by stating that the National
Standards Commission is the responsible authority in regards to qualifying
trade measurement devices and the associated uncertainties through issue of
certification under regulation 13 of the National Measurement Act 1960.405
Recent developments (June 2003) have occurred at institutional levels for the
evidentiary needs of verifying measurements used for legal purposes.
According to the Commonwealth National Standards Commission: Certificates of verification of reference standards of measurement are legal instruments under the Regulations in accordance with the Act. As such they may be used as prima facie evidence in all legal proceedings. They constitute a useful evidentiary facility which can obviate the need for legal proceedings to utilise the full scope of the rules of evidence and the common law. It can also obviate the need for witnesses and/or experts to be called to attest to the veracity of verifications of reference standards of measurement used to support measurements made for legal purposes.406
A detailed review of a case (arguably an Australian precedent in this matter)
dealing with a question of geographical position is explored in view of the
burden of proof for satellite-derived positions. This burden of proof was
examined as part of this dissertation at a time prior to knowledge of verifying
standards of physical quantities of position, or recognised value standard of
position in Australia and its territories. The testing of the veracity of an
acceptance of a regulation 13 certification for the physical quantity ‘position’
as a recognised value standard or other has not occurred in legal proceedings to
date (June 2003).
Proved Guilty,’ The Queensland Surveyor, vol.2000, no.1 February, pp.43-44. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter Spring 1999 405 See Commonwealth Department of Industry Tourism and Resources, 2003, National Measurement Institute web site, Available on-line Internet http://www.measurement.gov.au/index.cfm (accessed June 2003) with a link to National Measurement Policy Standards. 406 National Standards Commission (Australia), 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003, Introduction section on Certificates as Evidence, page vii. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003)
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5.5.3 Appeal of Evidence relating to Geographical Position
This section reviews the central argumentative issue of the evidential
requirements for proof associated with a geographical position. Further it
should be noted that the literature review found extremely little Australian
reporting on this issue, but several latter cases have cited the Chinn Yaou Fa -
V- Morris (1987) case. It should be noted that the Supreme Court of Western
Australia - Court of Appeal,407 references the case in question as Chinn Yaou
Fa -V- Morris (1987) 87 FLR 36 Supreme Court of Western Australia - Court
of Appeal with the original case no.540 of 1985 as Chinn Yaou Fa –v- Morris
[1987] 46 NTR 1, supreme court of Northern Territory.
Some relevant details of the case challenging the geographic position of the
fishing vessel include: On 24 March 1985 a foreign fishing vessel the “Ming Yang 21” was intercepted by HMAS Bunbury off the west coast of Western Australia. It is alleged that at the time that the vessel was intercepted she was in the position 12 degrees 12 minutes south, 124 degrees 20 minutes east. Assuming, for the moment, the correctness of that position the vessel was then in an area of proclaimed waters comprised in the Australian Fishing Zone pursuant to the Commonwealth Fisheries act 1952. HMAS Bunbury was under the command of Lieutenant Commander David Oliver.408
The master of the vessel Ming Yang 21 was convicted and subsequently
appealed to the Supreme Court. Included in the grounds for appeal were the
following important claims relevant to evidence relating to geographical
position: (g) accepting evidence of a geographical position of the Appellant's said fishing vessel at the relevant time on the evidence of a reading from an electronic device namely a Satellite Navigator without any or any proper or sufficient proof of the accuracy of the device or any electronic or navigation system of which it constituted a part.
407 Supreme Court of Western Australia - Court of Appeal, 2003, Internet database of cases, precent cases on this issue, Available online Internet http://www.austlii.edu.au/au/cases/wa/WASCA/ (accessed Feb. 2003) 408 Supreme Court of The Northern Territory, 1985, Chinn Yaou Fa –v- Morris, No.540 of 1985, Statutory Interpretation – Commonwealth Fisheries Act- Evidence- International Law- Constitional Law(1987) 46; NTR 1;(8 May 1987) paragraph 1.
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(h) that there was no or not sufficient evidence that the Appellant was within the said zone at any material time.409
The judgement of Justice Asche (1985) contains much relevant
information relating to evidence of geographical position. Relevant and
important extracts are included in this dissertation as it contributes to
the testing of the hypothesis. The comments included are critical to the
central legal argument surrounding “scientific instruments” commonly
known as GPS for derivation of position and time with associated
uncertainties. At para. 21 through 32:
Ground (g) alleges that the Magistrate was in error in accepting evidence of a geographical position of the Appellant's said fishing vessel at the relevant time on the evidence of a reading from an electronic device namely a satellite navigator without any or any proper or sufficient proof of the accuracy of the device or any electronic or navigation system of which it constituted a part.
Ground (h) alleges that "…there was not or no sufficient evidence that the appellant was within the said zone at any or any material time."
These two grounds are taken together by Mr McCormack [counsel for the appellant] as being interdependent. They depend upon the nature of the evidence given on behalf of the prosecution which related to the use of an instrument known as a satellite navigator to fix the positions of the vessels at the time of the apprehension of the Ming Yang 21 [the vessel]. It is one of Mr McCormack's points that no proper description of a satellite navigator system was given to the court below. It is sufficient I think, for the purposes of this appeal, to appreciate the general principle that transmissions passing between orbital satellites and ground tracking stations can be received and translated by this instrument in such a way as to fix the position on the earth's surface where that instrument is at the time it receives the signals. Mr McCormack submits:-
1. that the instrument known as a satellite navigator, if it is a scientific instrument, is not one of that class of "notorious" scientific instruments as to which there is a common law presumption of accuracy and regularity.
2. that if it is not a notorious instrument it accuracy must be established by expert evidence.
3. expert evidence of a properly admissible nature was not forthcoming in this case.
4. there is therefore not sufficient evidence of the position of the Ming Yang 21 at the time of her interception.
As to the first proposition I am inclined to agree with Mr McCormack' that a satellite navigator does not yet fall within "a class of instruments of a scientific or technical character, which by general experience (are) known to be trustworthy, and are so notorious that the court requires no evidence to the
409 Supreme Court of The Northern Territory, 1985, Chinn Yaou Fa –v- Morris, No.540 of 1985, Statutory Interpretation – Commonwealth Fisheries Act- Evidence- International Law- Constitional Law(1987) 46; NTR 1;(8 May 1987)
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effect that they do not fall into such class before allowing the presumption in question to operate with regard to readings made thereon." Per Herring C.J. – Porter v Kolodzeij (1962) VR 75 at 78.
In Crawley v Laidlaw (1930) VLR 370 at 374 Lowe J. treats this presumption as based upon the concept of judicial notice. “I do not doubt that in appropriate cases the Court will use its 'general information and…knowledge of the common affairs of life which men of ordinary intelligence possess.' – Phipson on Evidence (6th Ed.). p 19 – and that of the nature of most if not all, of the instruments mentioned in the paragraph cited from Taylor the Court would require no evidence in order to raise the presumption relied on.”
The "instruments mentioned" in Taylor's work on Evidence 10th Ed. to which His Honour was referring include watches, clocks, thermometers, pedometers, aneroids, anemometers and "other scientific instruments". The expression "other scientific instruments" however is not in the context of blanket admission of the class but on the contrary clearly carries the meaning "other scientific instruments which have achieved judicial recognition". The very insistence that such instruments should be "notorious" obviously disqualifies new or comparatively recent inventions no matter how precise or accurate they may be. This despite the probability that generally the newer the device the more accurate it is likely to be. The water power of the clepsydra was replaced by the mechanical power of clockwork which in turn was replaced by electronic devices; with a marked improvement in efficiency and accuracy at every stage. But the law is cautious – perhaps sometimes overcautious – rather than inconsistent. Once an instrument gains sufficient recognition the law will permit the shorthand of judicial notice. Until then it must be the more strictly proved. ….. para.29. While it might be suggested that the common law takes an unconscionable time to recognise many scientific instruments in common and accepted use, parliament can, and often does, accelerate that process by building in various presumptions into legislation based upon the accuracy of such instruments. ….. No doubt a satellite navigator instrument may one day fall into the class of notorious instruments but on the principle set out above I must rule that that day has not yet dawned. Mr McCormack makes the point that the Commonwealth parliament has not so far provided by legislation for the recognition of the instrument itself without further proof, or for readings taken from the instrument to be prima facie evidence of position. It may well be, in view of the importance attached to these instruments and their readings that in this case and no doubt others to follow that the legislature should give its attention to these matters.
Para 31. Meanwhile however the position is as set out by Herring C.J. in Porter –v- Kolodzeij (supra) at p 78:- “Where, however, the instrument in question does not fall within the notorious class, then…evidence must be given to establish that it is a scientific or technical instrument of such a kind, as may be expected to be trustworthy, before the presumption (i.e. of its working accuracy) can be relied upon.”
How far should such evidence go? A complicated scientific instrument may require a battery of experts in various fields if the rule against hearsay is to be strictly applied.410
410 Ibid., para. 21-32, p.5-7
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Returning to the appeal case arguments (1987), insufficient evidence and
expert testimony surrounding the geographical position of the Ming Yang 21
[the vessel] at the time of interception.
Lieutenant Commander Oliver and Lieutenant Victor [officers of the arresting navy vessel] gave evidence of their training and experience in navigation. But neither, he says, "explained the general function" of a satellite navigator or "testified to its acceptance as a reliable unit". Certainly they testified as to its accuracy. Lieutenant Victor said:- “Satellite navigation, the accuracy of the system was confirmed the day before, on approach to Ashmore Reef, when I conducted a celestial observation that morning and my position was within [0].75 of a mile of the satellite derived position.” So he gave direct evidence on this aspect. Lieutenant-Commander Oliver said:- “The satellite navigator will depend on your movement at the time, and the number of passes that it goes through, but its accuracy will be guaranteed to well under two miles. And if you're near stationary it can be exact as a few hundred yards.”411
Justice Asche comments that these statements sound rather more like hearsay
although it may be a summation of the witnesses own direct observations.
Justice Ache continues by introducing totality of evidence to the arguments:
I am of the view that Mr McCormack is correct that it was not sufficiently proved to the court exactly what a satellite navigator was, how it functioned and whether it is accepted as a reliable instrument in its field. Had the ship's position depended entirely on the satellite navigator readings it may well be that on the evidence before the Court of Summary Jurisdiction there was not a sufficient basis to make a finding of that position. But in my view the argument of Mr McCormack that it must follow that there was no sufficient evidence of the position of the appellant completely falls down when one looks at the totality of the evidence on this point placed before the court. The totality of evidence did not entirely depend upon the use of the satellite navigator system. It depended on a number of uncontradicted matters which together build up a very strong case – indeed in my view a case beyond reasonable doubt - that the position of the appellant's vessel at the appropriate time was where the expert witnesses called for the respondent said she was.
Both Lieutenant-Commander Oliver and Lieutenant Victor must be accepted as skilled navigators. Lieutenant-Commander Oliver has had 20 years experience in the navy and has done courses in navigation and has had substantial practical experience and has even been responsible for the navigation training of junior officers. He has kept up his navigation experience and says that prior to his current posting he spent a "four week concentrated navigation revision".412
411 Ibid., para. 40-42, p.8 412 Ibid., para.44-46, p.8-9.
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Justice Asche then explained in some detail the requirements of the rules of
evidence relating to the admissibility of expert testimony. Paragraph 54
summarises the situation of this case.
In the face of this evidence, and accepting that reliance was certainly placed on the satellite navigator, (which along with all other navigational aids had been checked and was within acceptable standards) and accepting the expertise in navigation of the two officers the conclusion on the totality of the evidence is that the positions given of the appellant's vessel when intercepted were correct.413
Horlin (2000) directly adds to the summary arguments with:
The appeal was dismissed and it was held that the prosecution had established a prima facie case that at the time of interception the vessel was in the prohibited zone. The accuracy of the satellite navigator used to determine the position of the vessel at the relevant time could be inferred from all the proven circumstances. The Mehesz case referred to in the judgement is also a leading authority on the sufficiency of evidence of experts that use the instruments in question, instruments with computerised components and where there is no evidence as to the correctness of the instrument's programme.414
In essence, the geographic position of the appellant vessel was not proved by
solely relying on the readings of a satellite navigator. This case also
highlighted that it was not sufficiently proved to the court exactly what a
satellite navigator was, how it functioned and whether it is accepted as a
reliable instrument in its field for determining a geographic position.
The current efforts (June 2003) of the National Standards Commission are
beginning to address this legal determining of a geographic position at a point
in time. These efforts appear to be progressing through a verifying authority,
such as GeoScience Australia, to issue certificates of verification of reference
standards of measurement (for position) as legal instruments under the
Regulations in accordance with the Australian National Measurement Act.415
413 Ibid., para.54, p.11. 414Horlin, E., 2000, ‘GPS- Presumed Accurate Until Proved Guilty,’ The Queensland Surveyor, Institution of Surveyors Australia- Qld Division, vol.2000, no.1 February, page 46. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter Spring 1999. 415 National Standards Commission (Australia), 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003. page vi. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003)
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5.5.4 Discussion Legal traceability of measurements is required in any criminal proceedings
except where reliance can be made on the common law presumption of the
accuracy of scientific or technical instruments. A challenge in a civil action,
such as a boundary dispute, that GPS measurements are not legally traceable is
accompanied by a burden of proof that the measurements are in fact inaccurate. Australian courts have indicated that the common law presumption of accuracy of scientific or technical instruments co-exists with the National Measurement Act 1960 (Cth). If the presumption of accuracy is relied upon it is not absolutely necessary to show a direct link to a national standard. The rules of evidence set out in Mehesz (supra) need only apply whereby instruments not regarded by the courts as "notoriously accurate" need accompanying evidence of accuracy and use. It is in my opinion that legal traceability of GPS measurements in cadastral surveys is in reality an extremely minor issue. In the whole scheme of the legal cadastre, measurements and their traceability are generally subordinate to other evidence. In basic terms, reliable crown monuments and freehold abuttals usually have priority over measurements.416
Horlins concluding remarks provide an opinion on the debate independently of
the recent international concept of measurement equivalence, such:
Provided surveys conform to recognised best practice the presumption of accuracy may be relied on and legal traceability shouldn't need to enter the equation.417
These remarks are in direct contrast to the organisational efforts reviewing and
assessing requirements towards legal traceability. The arguments previously
presented on traceability (chapter 5 section 5.2-5.4) support the logical notion
of regular comparative testing of a measurement system against a high quality
geodetic test-range network using a combination of stable pillars and ground
monuments allowing sufficient equipment and software validation with
documentation. A documented performance report supported by suitable
416 Horlin, E., 2000, ‘GPS- Presumed Accurate Until Proved Guilty,’ The Queensland Surveyor, Institution of Surveyors Australia- Qld Division, vol.2000, no.1 February, page 45. Reprinted from Timepiece – Western Australian Institution of Surveyors newsletter Spring 1999. 417 Ibid., p.45.
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statistics should ensure conformance that the equipment is in technical working
order and would be additionally be suitable as evidence that should survive a
civil court challenge. The most recent concept on this issue appears to create an
indirect link to the AFN by connection to at least three existing Regulation 13
positions, which have been either directly or indirectly connected to the
AFN.418 The positional uncertainty on the existing Regulation 13 positions
must be commensurate with the required uncertainty for the new point.419
The specific wording provided by the ICSM group in the Standards and
Practice for Control Surveys (SP1) version 1.4 issues a qualifier statement to
the limitations section on the use of GPS for legal purposes. This statement
appears to have been adopted, in various similar forms, by state statutory
bodies such as the Queensland Surveyors Board. These guidelines are specific to utilising the Global Positioning System (GPS) in circumstances that follow a quality assurance approach. …… Because approved methodologies for establishing legal traceability of length measurement for GPS do not currently exist under the Australian National Measurement Act (1960), GPS should not be used as the sole method of measuring length in legal surveys within Australia. Surveyors using GPS for legal purposes within Australia must adhere to the requirements of the appropriate verifying authority in the State or Territory.420
It is clear that this current status-quo will prevail for the professional surveyor
until formal recognition of an alternative confidence and verification process is
established by the responsible verifying authority and approved by the National
Standards Commission under regulation 13 of the National Measurement Act
1960.
418 refer figure 5.4. 419 National Standards Commission (Australia), 2003, Verifying Authorities Handbook, National Standards Commission of Australia, third edition 2003. Section 11.4.2 page 67. Available on-line Internet http://www.nsc.gov.au/PDF_WORD/Info/Documents/vah.doc (accessed June2003) 420 Section 2.6.2 page B-17 is on noteworthy inclusion that qualifies the common stand on using GPS for legal purposes. ICSM, 2000, Standards and Practices for Control Surveys, SP1 version 1.4, Intergovernmental Committee on Surveying and Mapping, Australia, available on-line, Internet, http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (accessed Nov. 2001)
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5.6 Summary
This chapter has presented a two-part discussion. The first part is an overview
of measurement systems with principle measurement concepts examined in
order to gain an appreciation of the underlying principles of a measurement
system.
International traceability of measurements can be achieved by way of
international comparisons and key comparisons of national measurement
standards. The concept of international traceability has been reviewed because
of its importance in the context of a global positioning system and as a location
and precise time transfer tool. The standards of measurement, particularly those
associated with time, used in the global positioning system are realised and
maintained by appropriate organizations, largely in the United States.
Legislative statements relating to quantitative measurements made in relation
to cadastral activities have been reviewed with the specific requirement of GPS
methods acceptable to the state authority highlighted. Standards of accuracy
prescribed by state surveyors boards is summarised by way of Boey’s (1999)
investigation. It is noted that only three of the eight jurisdictions make mention
of the position quantity. The critical review highlights the need for satellite-
based technology, such as GPS, to meet requirements relating to verification of
survey measurements, calibration and standardisation of survey equipment and
for such technology to be adequately described in suitable terms including
accuracy standards relating to position and time.
The second part of this chapter examines the traceability of the quantity
‘position’ through the National Measurement Act 1960 and explores the timing
issue as the technology matures. Section 5.5.4 examined the appeal of evidence
relating to geographical position. It furthered the discussion on a potential
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challenge in a civil court action such as a boundary dispute relying on GPS
measurement positions. The premise that the GPS measurements themselves
are not legally traceable is accompanied by a burden of proof that the
measurements are what they purport to be.
It is recommended that surveyors continue to follow best practice guidelines in
performing GPS for control and engineering surveys. Surveyors undertaking
GPS measuring should regularly perform a zero-baseline test to examine the
correct operation of the antenna and internal receiver’s performance under an
identical satellite geometry and radio reception configuration.
Arguably of more importance, surveyors to perform GPS measuring over a
special test network that includes at least 3 geodetic control points of known
three dimensional position with documented uncertainties associated to those
control point positions. However, four or more points provide a degree of
redundancy and consistency of the internal network stability. It is also strongly
recommended that several independent connections be made to the Australian
Fiducial Network (AFN) through the spatial data infrastructure known as the
Australian Regional GPS Network (ARGN).
It is becoming evident that surveying statutory authorities, at some point in the
near future, will need to come to terms with the issue of satellite-based survey
techniques utilised for extensive cadastral measurement activities. Suitably
qualified and trained surveying professionals are the best people to undertake
coordinate collection technology applied to rural cadastral surveys. The
operational and logistical environment of rural surveys is one that would
benefit most from such a regulatory change, provided the performance
indicators of the measurement system are regularly monitored to ensure
conformance to accuracy standards.
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213
CHAPTER SIX
CONCLUSIONS AND FUTURE DIRECTIONS
So strong was the support from the combination of my labor of seventeen years
on the observations of Brahe and the present study, which conspired together, that at first I
believed I was dreaming, and assuming my conclusion among my basic premises.421
6.1 Conclusions and Recommendations
In conclusion, the major aim of this dissertation has been to explore the following
hypothesis:
GPS co-ordinate survey control methods can provide efficient rural
cadastral surveys suitably recognised by authorities and improve the
integrity of spatially related rural boundaries.
421 Fields, J.V., 1999, Quotations by Johannes Kepler- A Compilation Work. Keplers quotation by way of 'Quotations Index' of School of Mathematics and Statistics University of St Andrews, Scotland.
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214
This research undertaking and detailed review shows many assumptions of the
fixed earth notion and fixed cadastral monuments do not hold correct. Accuracy of
measurements and improvements in technology precision show that overall
measurement uncertainties of the real-world are diminishing. This dissertation
investigated measurement information communicated by a language of coordinates
or other relative positional representations (vectors).
New technology approaches adopted for collection and description of spatial
characteristics utilise a coordinate information approach. Recent technical advances
in space based positioning systems are demonstrating capacity to replace some
conventional survey approaches, especially when aiming for consistent sub-
centimetric three-dimensional positioning. This dissertation has explored and
reviewed perceived concern with positional and measurement information
communicated by coordinate representations. Related to this point, the notion of
best evidence for cadastral reinstatement has been considered.
The cadastre of Queensland is maturing and evolving both on land and in marine
environments. GPS technology is bringing more accurate measurements and
improvements in precisions into the cadastral measurement function. Review of
literature of similar applications has shown advances in measurement methods does
provide greater integrity to the measurements that support new property surveys.
A conclusion of this research is that managers of spatial information need to be
making the best use of measurement information as and when it becomes available.
The concepts of Measurement Based Spatial Information Systems have been
investigated as a management technique to provide means of organising and
containing digital survey data. This digital survey data contains the source
measurement information and is held for future use or adjustment purposes. In
answering queries from the measurement database, adjustments are performed
Chapter Six: Conclusions and Future Directions
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from the first class source measurements. This approach includes the use of up-to-
date spatial information as and when it becomes available.
Management principles are to make best use of data as and when it becomes
available. As such, the concept of a measurement based spatial information system
has merit in that it will provide management with a systems approach to monitor
achievements and other performance metrics of the cadastral and geodetic
information layers. The capture of measurement information using new GPS
collection techniques can offer efficiency in undertaking surveys for geodetic,
cadastral and engineering purposes. Review of the literature has generally shown
that the storage of raw measurement information to a MBSIS for the intention of
future use will allow opportunistic adjustments to make best use of new
information.
Descriptions of land parcels based on coordinate information alone have been
strongly argued against in light of the totality of evidence required and lack of
redundancy with digits that comprise a coordinate. The aim of legal policies
relating to land descriptions is to determine the intention of the parties in
establishing the boundaries expressed in the form of written documents. The
principles are that most weight should be assigned to points that the respective
parties are least likely to be mistaken about. This is the key to cadastral
reinstatement. A coordinate-alone description of a property corner does not meet
this legal principle.
This investigation has found that relying alone on coordinate position descriptions
of land boundaries (rural or otherwise) does not uphold community expectations
relating to adequate description of the location of property rights and interests.
Society places much importance on land specifically in terms of assurance of the
Chapter Six: Conclusions and Future Directions
216
security of land title and confusion of the sufficiency of description through
coordinates alone will erode those community expectations.
Investigation of this issue has particularly useful outcomes to developing nations
contemplating design of new geodetic and cadastral information systems. This
work has discovered dynamism issues relating to technical achievements,
knowledge and understandings of regional geodynamics.
It is clear from overseas land administration that government authorities and
organisations dealing with spatial information will require an automated multi-
purpose cadastre to facilitate appropriate land management, land tenure and
cadastral infrastructure in support of considering concepts of sustainable
development. The effective and efficient use of surveyed information relies on data
redundancy. This review has shown that the need remains to preserve redundancy
in automated systems for communication of legal and other geometrical
relationship reasons. However, it is acknowledged that more research work is
required into communication theories and management of risk applied to cadastral
surveying and mapping functions in Australia.
Research of the hypothesis statement ‘suitably recognised by authorities’ has
revealed that the legal implications have not been fully completed at the national
level. The Australian Standards Commission, through its verifying authority has
yet to release a practical means for acceptance of GPS derived positions. However,
GeoScience Australia and CSIRO are conducting research in this area such that
GPS positioning will be suitably recognised by authorities. Surveying with GPS
has some limitations but is generally an efficient data collection tool producing
high quality results for broad applications ranging from geodetic surveys through
to property boundary measurement tasks and location of services within and
adjacent to those properties.
Chapter Six: Conclusions and Future Directions
217
The issue of verification and traceability of measurements has been reviewed and
the relatively new physical quantity ‘position’, has yet to be fully realised in the
spatial science community. Discussion has occurred on a potential challenge in a
civil court action, such as a boundary dispute derived from GPS measurements,
that the GPS measurements themselves are not legally traceable is also
accompanied by a burden of proof that the measurements are what they purport to
be. At this time, a satellite navigator (GPS instrument) used by the Australian Navy
is not one of those notoriously trustworthy instruments accepted by the court as a
sole means to determine geographical position. Examination of evidence
requirements relating to geographical position have been explored with the
discovery that a verifying organisation is currently (June 2003) considering the
technical details of position verifications in regards to the National Measurement
Act 1960. This assessment reaffirms the current advice given by the Queensland
Surveyors Board in relation to the issue of legal traceability and connection to State
control survey.
The investigative study have raised many technical issues and concluded that use
of best- practice guidelines for global positioning system technology in the spatial
science industry is to be strongly encouraged for purposes of applying geodetic
techniques to cadastral measurement problems. Related to this conclusion is the
belief that if legislative changes are made in the methods of applying geodetic GPS
techniques to the cadastral surveying measurement function, the cadastral
surveying practitioner will require skills updating in fundamental geodesy with
particular emphasis on modelling relationships between orthometric and/or geoidal
and ellipsoidal heighting.
Chapter Six: Conclusions and Future Directions
218
6.2 Open questions for future research
This research undertaking has shown that some technical information technology
issues require consideration and testing before implementation of a measurement
based spatial information system could occur on a local government or local
controlled area pilot project.
A risk management strategy requires further research applied to cadastral surveying
and mapping production functions. Whilst some work has been done in the State of
Victoria, the Queensland Department of Natural Resources and Mines should
examine this issue for cadastral surveys and geodetic infrastructure. These risk
management strategies also require understandings of additional systematic
redundancy and minimising entropy influences. Holistic risk management of the
land administration activities in the State of Queensland would be a worthwhile
institutional undertaking to identify if appropriate resources and sub-systems are
operating effectively.
Further research is required into the area of data standards for MBSIS inputs.
Standard data collection formats are required for electronic total station, GPS
techniques and future measurement technology approaches (inclusive of
verification, test comparisons or others) that may eventuate. How does this
information relate to Australian information standards and data presentations?
Further research is also required into avenues of digital data lodgement for
‘standardized’ measurement based spatial information to a central database or
distributed databases. This research requires consideration of national efforts to
build spatial infrastructures including a unified cadastral model.
Further investigation is required of economic and organisational issues of
measurement based spatial information systems implementation based on a local
Chapter Six: Conclusions and Future Directions
219
authority region. This would need to extend to exploring the costs associated with
an implementation and the desired and actual foreseeable benefits (tangible or
other) from such a proposal. This aspect would normally be undertaken as part of a
detailed pilot study requiring rigorous analysis and what-if scenarios on a small test
area with diverse characteristics. The sub-issue of survey and mapping
infrastructure charging as part of the land development process requires further
investigation.
This economic and organisational avenue also requires effort in examining
automation aspects of maintenance functions of a system. This requires spatial
information management expertise in design of a suitable land administration
system. One objective of such a land administration reform investigation would be
to quantify sustainability aspects of any proposal in light of the international vision
of cadastre 2014.422
State survey authorities will need to address in the near future detailed issues of
position-based survey techniques used for cadastral measurement activities. The
operational and logistical environment of rural surveys is one that would benefit
most from such a prescriptive change to survey regulations, provided the
performance indicators of the measurement system are regularly monitored to
ensure conformance to accuracy standards.
422 FIG, 1998, Cadastre 2014: A Vision for a Future Cadastral System. F.I.G. Commission 7- Cadastre and Land Management publication. Edited by Kaufmann, J, and Stendler, D., 1998 Also available on-line Internet http://www.swisstopo.ch/fig-wg71/cad2014.htm (accessed May 2001)
Chapter Six: Conclusions and Future Directions
220
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
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APPENDIX A
INVESTIGATIVE STUDY: RURAL CADASTRAL
SUBDIVISION BY GPS TECHNIQUES
It is nothing short of a miracle that modern methods of instruction have not yet
entirely strangled the holy curiousity of inquiry.423
A.1 Introduction This section reviews the topic rural cadastral surveys using GPS measurement
technology. The purpose of this investigative study is to review in some detail
the survey methods utilised in 1991 and to highlight issues that demonstrate
measurement standards and technology have evolved and matured, along with
methods and obtainable positional precision. The purposeful application of
423 Albert Einstein quotation. Cited in Eves, H, 1988, Return to Mathematical Circles, Boston 1988. - Albert Einstein quotation by way of 'Quotations Index' of School of Mathematics and Statistics University of St Andrews, Scotland URL: http://www-groups.dcs.st-and.ac.uk/~history/Quotations/index.html (accessed December 2001)
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improved measurement technology and systems will ultimately advantage the
surveyor and subsequently the community, in the conduct of cadastral surveys.
The author has been involved in education of surveying professionals in the
training and application of GPS surveying methods. The author has also
undertaken various connections between PSMs and the cadastre at Pinjarra
Hills and Linthorpe Valley using a multitude of GPS measurement solutions.
The author has also recently conducted field trials of geodetic GPS
measurement comparisons to certified EDM baselines.
Figure A.1: The author undertaking a cadastral connection experiment to nearby geodetic control. Survey utilised dual-frequency Trimble geodetic GPS instrumentation, Pinjarra Hills, 1997.
A.2 Rural Subdivision by Geodetic GPS Project Overview
One of the first survey plans acceptable for registration in QLD using GPS
measurement methods was the Blackall and Cunnamulla subdivision project
undertaken by John Morrow L.S. of the private-practice surveying firm
M.J.Hedges Geomeasure. 424 This paper was selected because it is a
Queensland application and it was one of the first registered survey plans in
Queensland to use the on face statement….lines have been determined by GPS
424 Morrow J.D., 1991, ‘Subdivision of Extensive Rural Freehold Land using GPS,’ Proceeding of 12Th Surveying Industry Seminar- University of Southern Queensland, Toowoomba, November 1991.
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methods. In addition, it has been carefully chosen as a reference point to study
in detail aspects, shortcomings, opportunities and evolutionary technology
approaches in this application. GPS measurement technology was at an infant
stage in this country in 1991 at the time of this project. This investigative study
contribution is worthwhile to the overall thesis as it reviews several issues
relating to this approach in-light of the growth of satellite-based measurement
methods and the so-called maturing of “best-practice” survey guidelines.
The method of photogrammetric restitution has for some time, been acceptable
to the registering authority for deriving relative co-ordinates and performing
limited cadastral surveys on a case-by-case basis. The particular method under
examination in this project is the specific use of GPS measurements applied to
collection of cadastral evidence. Arguably, the method had been innovative and
time expedient for its time.
Figure A.2: Cunnamulla rural survey study area (enhanced from Morrow).425 Project area is approximately 25 kilometres by 30 kilometres in size held in 12 parcels.
425 Ibid.
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The project involved cadastral surveys to perform rural subdivision covering
approximately 40 000 hectares at Blackall and approximately 75 000 hectares
at Cunnamulla. In synthesising the project requirements from Morrow’s paper,
the project brief required that the subject land be sub-divided into lots
containing areas of no greater than 2500 hectares. The new lots would be fully
freeholded in tenure. The client was not concerned if the boundary alignments
were not going to be cleared, blazed or marked as the newly created boundaries
were not to be fenced in the foreseeable future.426
Figure A.3: Extract of Geodata Raster 250K Topographic Map over the Cunnamulla project study area. 427 Original map scale 1:250,000 (1993). 426 Ibid. 427 Cunnamulla Topographic Map 1:250,000 series, Sheet SH55-2, Series 1501, Edition 1, Produced by Royal Australian Survey Corps 1993. Printed by RASC 1994, Geodata by AUSLIG - Raster 250K CD-Rom #2.
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With reference to the topographic map of the Cunnamulla areas and comments
by Morrow, it appears that the topography and vegetation cover favoured
traditional orthodox traversing to complete the boundary survey with
regulation marking. However, Morrows’ paper indicated that this traditional
method would render the project costs prohibitive given the distance between
proposed new boundary corners. According to Morrow, the client preferred the minimisation of creation of new roads and to avoid the creation of narrow strips creating so called hatchet blocks. Approval in principle for the subdivision to proceed was sought and granted from the local government authorities of Blackall Shire council and the Paroo Shire council.428
A.3 GPS Measurement Approach Given the current (2003) GPS measurement techniques in production use for
engineering and control purpose surveys, it is worthwhile examining the GPS
site selection phase of this investigative study project. Morrow’s original
comments summarize the situation: Generally the reconnaissance involved the site selection for the GPS stations which were ideally to be located as close as possible to the positions of the new subdivision corners. In turn the new boundaries were to be located if possible close to the fence lines where accessibility would limited the travelling time between stations for observations to a minimum. The use of the vehicle speedo and a compass were adequate to perform this aspect of the project.429
Morrows’ findings reported that the GPS observations involved standard static
survey techniques with ten degree elevation masks, however, only 30 minutes
of observation data was collected per station with up to 100 measurement to 4
satellites being used (around 15 second epoch). Two GPS instruments utilised
428 Morrow J.D., 1991, Subdivision of Extensive Rural Freehold Land using GPS, Proceeding of 12Th Surveying Industry Seminar- University of Southern Queensland, Toowoomba, November 1991 p.3. 429 Ibid, p.3.
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for this project consisted of the Trimble brand single frequency L1 4000 ST
models.430
This observation data approach is markedly at odds with current mathematical
reduction methods as prescribed in Trimble’s Geomatics Office software
manuals. 431 Support of this point derived from the observation requirements of
Trimble’s series 4000 operation manual (section 1.2.1 Control Surveying).432
Specifically, the manufacturer specifies - Static surveying is the most precise surveying procedure, and the slowest. It requires observations of at least four satellites for a period of 30 to 60 minutes. It yields baselines that are precise to better than ±5 mm + 1 ppm There are two types of static surveys: single- and dual-frequency. Single-frequency static surveys are appropriate for surveys with baselines shorter than about 15km under good atmospheric conditions. Dual-frequency static surveys are required to ensure accurate results in geodetic control surveys. Such receivers are used with baselines from 15k m up to about 800km under good conditions. FastStatic surveying is a less precise procedure, but is substantially faster. It requires simultaneous observations of at least four satellites for a period of 5 to 20minutes. It yields baseline components that are precise to better than ±1 cm + 1 ppm. Because of the relatively short observation time, a single mobile receiver customarily is used to make observations at several unknown marks in the course of a survey.433
The baseline linkage of a measurement network to surrounding control, or a
relative local network covering the two project areas are not exactly clear based
on the original paper. However, the pre-subdivision linear geometry and
proposed subdivision alignments are included to provide an overview of the
spatial relationship of existing and proposed boundary geometry.
430 Ibid., p.6 431 Trimble Navigation Limited , 2001, Trimble Geomatics Office User Guide, Volume 1 & 2, version 1.5, revision A January 2001. ALSO of relevance to this inquiry is Trimble Navigation Limited, 1994, Trimble GPSurvey software reference manual, Revision A, section 3-13, November 1994. MORE recently the aprior observation requirements contained in Trimble’s Network Adjustment User Guide, version 1.5, revision A January 2001, p. 67 Constraining Control Points in the Project Datum. Trimble Navigation Limited 432 Trimble Navigation Limited, 1995, Series 4000 Application Guide, Surveying and Mapping Division, Trimble Navigation Limited, revision A February 1995 Section 1.2.1 433 Ibid., p.1-5.
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Figure A.4: Cunnamulla pre-subdivision and proposed boundary geometry.434 A.4 Discussion on Method Analysis
434 Enhanced diagrams sourced from Ibid., p.5
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The survey method utilised for the Blackall project apparently consisted of
single GPS radiations and calculated join bearing and distances between points
associated with the subject parcel. This employed method is noted as weak and
geometrically dangerous by comparison to current standards and practice for
control surveys, excluding the misclosure analysis approach for RTK-GPS
techniques as described in ICSM Standards and Practice for Control
Surveys.435
Figure A.5: Diagram of non-recommended single-radiation GPS method employed in original survey. The single radiation method is not an acceptable method for a GPS only
measurement approach because it has no geometric closure function. However,
other connections on a subject parcel included survey data from traditional
traversing methods may provide assistance in performing a loop or network
closure. A potentially dangerous situation arises where the actual new line to
be determined has not been physically measured (no direct vector) with
435 Refer to the comprehensive document by ICSM, 2000, SP1 Standards and Practice for Control Surveys Version 1.4 December 2000. Section 2.6.8 Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (June 2001)
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displacements of single radiation GPS positions being calculated or derived.
This investigative study has found that the use of geodetic GPS instruments
have appeared to have been used as a simple extension of an EDM traverse
measurement tool.
Ideally, in 1991, several independent checks and comparisons of baseline
vectors should have been made with calibrated EDM total station instruments.
The Queensland Surveyors Operation Manual at section B2 –part 7.2 includes
a statement to this effect when using non-traditional approaches.436
The current best practice guidelines for the use of GPS for survey applications
recommend that for completely independent results and for quality control
purposes, each point should be re-occupied in a different session with different
satellite geometry.437 This is reinforced by the independent occupation
requirements for surveys Class B and higher as part of the recommended
survey and reduction processes of standards and practice of control surveys
(SP1).438
Review of Morrow’s traverse calculations indicates overall accuracy of each
lot achieved reasonable misclosure ratios. It is further speculated that the GPS
positions derived by radiations appear superior to the original survey traverse
data, some of which was collected using compass and perambulator. In
essence, it is the surveyor’s professional judgement of using the mathematical
misclose ratio as an indicator of overall acceptability that construes a mixed
measurement approach for accepting measurements for aiding in the location
of cadastral monuments related to the boundary corners. Interestingly, recent
436 Qld Surveyors Board, 2002, Qld Surveyors Operation Manual, published by the Surveyors Board of Queensland, available on-line Internet http://www.qld-som.com.au/ (accessed Feb 2003) 437 ICSM, 1997, Best Practice Guidelines Use of Global Positioning Systems (GPS) for Survey Applications, Version 2.0 - 1 November1997. Section of interest is the observational requirements for psuedo-kinematic and kinematic techniques. Available on-line Internet http://www.anzlic.org.au/icsm/publications/gps_surv.htm#prac05 (accessed January 2002) 438Refer to the Table 26 GPS Method versus Class Section 2.6.6 of ICSM, 2000, SP1 Standards and Practice for Control Surveys Version 1.4 December 2000. Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (June 2001)
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RTK-GPS best practice guidelines suggest a misclosure analysis approach
when this method is used for introducing survey control.
However, as previously discussed in chapter 2, the weight of evidence to
boundary location, and that which is least likely to be ambiguous, should
prevail over the measurement aspects. While at the time the measurement
approach of using geodetic techniques to a cadastral application was probably
fair, today the situation is somewhat different with best practice guidelines for
using GPS techniques encompassed in the national Standards and Practice for
Control Surveys documentation. The underlying principle is that community
and industry expectations are that professional surveyors provide sound and
accurate measurements.439
This investigative study has demonstrated a number of key documents and
organisations impact on the practice of conducting GPS surveys. It is not
foreseeable that members of the general public (amateurs) would or could
conduct a co-ordinate collection survey for boundary re-definition purposes
using marks on the ground and other evidence that would withstand challenges
from measurement standards or legal (Surveyors Board) challenges.
439 Of particular issue to the practice of GPS surveys for Surveyors is article 1 and the interpretive clauses to the Code of Professional Ethics for Surveyors. Article 1 - Professional Responsibility –“In the course of their professional life and in the exercise of their profession, surveyors shall accept an obligation of responsibility in relation to the community, the profession, their clients, their employers, employees and other surveyors”. Institution of Surveyors Australia, Qld Division, 1998, Code of Professional Ethics for Surveyors and Interpretative Clauses, variable pp., Available On-line Internet http://www.isaqld.org.au/Members/Documents/EthInterpret.asp (accessed Dec. 2002)
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Figure A.6: Sample R.P. from Blackall project noting the comments of measurement technique.440 (Lower right)
440 Enhanced plan sourced from appendices of Morrow J.D., 1991, ‘Subdivision of Extensive Rural Freehold Land using GPS,’ Proceeding of 12Th Surveying Industry Seminar- University of Southern Queensland, Toowoomba, November 1991
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The sample registered plan from the Blackall subdivision case-study utilises an
on-face statement on the plan relating to lines 8-11,15-21, 19-21 and 21-7, that
have been determined by GPS methods and have not been cleared or marked as
per recommendations of the Queensland Surveyors Operations Manual.441 The
original lot six on plan TB27 appears typically rectangular North-South in
shape as do many other lots in the region. Presumably, the surround of original
lot six has some fencing as evidence of occupation with regulation marking at
corners with some additional reference marks. The new lot design features four
newly created lots each with road access and reference marks (pins) placed in
association with the new geometric boundary intersection, for example - corner
21 between lot eight and nine and adjacent to lot ten.
Other factors affecting GPS measurement quality include acceptable criteria
for the dilution of precision (DOP) factor for describing satellite geometry and
configuration, along with positional root mean squared (RMS) factors. Morrow
indicates that these factors would appear to be deemed acceptable and ideal
from available literature at the time.
The Cunnamulla project adopted a different technique where it appears that a
leap-frog traverse arrangement with two single frequency GPS units have been
employed. Minimal detail on the survey technique is presented for this
particular project, except withstanding that the - observation time was increased to 40 minutes (per station) in the Cunnamulla project with around 120 measurements ideally being captured.442
Further comments of noteworthy inclusion to this case-study relating to the
techniques adopted in Cunnamulla –
441 Refer to Surveyors Operation Manual (QLD) Technical Section 4.0 Unmarked Corners and Boundaries and reference also to Section 27 of the Surveyors Regulation 1992. 442 Morrow J.D., 1991, ‘Subdivision of Extensive Rural Freehold Land using GPS,’ Proceeding of 12Th Surveying Industry Seminar- University of Southern Queensland, Toowoomba. P.5.
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comprised basically a closed traverse of some 74 kilometres in length with internal loops also further closing and strengthening the figure. The misclose achieved over the 74 kilometres being a mere 0.3 of a metre. [approximately 1:246,600 misclose ratio] By using this approach actual physically measured lines even though measured with GPS are determined instead of lines calculated from radiation.443
It is inferred from this statement that most of the cadastral evidence, for
example evidence of occupation consisting of fence-posts, original survey pegs
and other ground-based evidence, have been directly occupied for GPS
observations. It is not known how the location of reference trees have been
collected, but could be surmised that a nearby GPS traverse mark has been
used to make a connection to the reference tree with traditional total station
techniques. However, the issue of azimuth determination has not been
adequately addressed in my opinion for these connections. Ideally, sun
observations or daylight stellar observations would provide some re-
enforcement to the GPS determined azimuth whilst additionally confirming
and strengthening the weight of measurement data for reliability and
repeatability purposes.
443 Ibid, p.5.
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A.5 Comparison of Approaches – Then and Now Some of the differences between the survey approach undertaken in 1991 and
with the project being undertaken today (2003) are summarized as follows:
• The geoid-ellipsoid separation N-value derived from the early OSU
global model and applied to the whole of region. N-values are now
derived from a more refined and improved density model,444 such as
AUSGEOID98 model on a point-by-point basis. For example, station
13 in Cunnamulla project would now have a AUSGEOID98 modelled
value for N approximating 28.8metres, as opposed to the original
regional value of 12.2metres presumably derived from OSU91 model or
an earlier global model. 445
• Static survey techniques now use improved fast-static data collection
approach with 8-15minutes field observation for 5 or 6 common
satellites with some re-occupation of points as opposed to the 1991
approach of 30 minutes (should have been 45minutes as recommended
by the manufacturer) static field observation data collection.
• Shorter occupation times now possible with dual frequency
instrumentation. No selective availability degradation present in today’s
GPS signals. Post-processing of lines can now be routinely undertaken
with precise ephemeris or more reliable broadcast ephemeris and dual-
frequency GPS receivers. Dual frequency instruments practically
reduce ionospheric delays by modelling the differences between the
received frequencies of short baselines. Ionospheric delay is largely a
444 Hoppe T., and Stahl B., 1999, ‘Surveying at Ground – Getting GPS and Conventional Measurements to Agree,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited. pp.10. 445 Value derived on-line through AUSLIG Internet site for latitude and longitude (WGS84) of station 13. http://www.auslig.gov.au/geodesy/ausgeoid/nvalcomp.htm (accessed November 2000)
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problem for baselines greater than 20-30km in length.446 Accuracy
specifications call for double occupation requirement for higher than
class B survey control and improved quality control result checking and
reporting in automated software reductions.
• Least squares network adjustment would rigorously be applied today
using relative accuracy concepts and production of point error ellipses
at 95 percent confidence level. Recently, the ICSM Standards and
Practice for Control Surveys have revised documentation on least
squares adjustments and analysis using misclosure comparisons.447
• Arguably, the precision of differential point position – appears to have
been estimated in 1991. This is typical of surveys undertaken during the
1990s. Today, improved statistical reporting and a priori expectations
are normally undertaken in pre-analysis of a survey network.448
• Single radiation method (using GPS vectors as a traversing tool)
appears to have been used for Blackall survey in 1991 - network or
independent double radiation approach now used, particularly with the
more wide-spread use of RTK- GPS techniques up to 15 kilometre
distances.449 In 2002, ICSM adopted positional uncertainty and local
uncertainty as new, simple methods of classifying the accuracy of co-
ordinate information. Positional and Local Uncertainty are compatible
with the ISO Technical Committee 211 (Geographic Information and
446 Rizo C., 1999, Principles and Practice of GPS Surveying, School of Geomatic Engineering, University of New South Wales. Section 4.2.3. Available on-line Internet http://www.gmat.unsw.edu.au/snap/gps/gps_survey/principles_gps.htm (accessed Dec. 2002) 447 ICSM, 2002, SP1 Standards and Practice for Control Surveys,Version 1.5 May 2002. Section 2.6.10 and 2.6.11 Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (Jan. 2003) 448 Thomson D.B., Krakiwsky E.J., and Nickerson B.G., 1982, A Manual for the Establishment and Assessment of Horizontal Survey Networks, Division of Surveying Engineering, University of Calgary. Chapter 2 – Observations and their reductions p. 6-35. 449 Refer to the comprehensive best practice guidelines by ICSM, 2000, SP1 Standards and Practice for Control Surveys, Version 1.4, December 2000. Section 2.6.8 section on RTK control provides a suitable and appropriate example of using RTK techniques applied to a survey control application. . Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (accessed December 2001)
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Geomatics - WI19115) quantities of Absolute External Positioning
Accuracy and Relative Positional Accuracy.450
♦ Travel time between stations would be similar if the project was undertaken
today; however, more occupations and more intermediate travel between
stations would be required if undertaking the same survey. To undertake
the project to achieve a high measurement confidence, more time and hence
more survey project costs would be required to be borne by the client to
meet their objectives with confidence.
♦ It is possible to use a synchronisation approach to data collection for fast-
static techniques, although the leap-frog approach with two receivers as
used in 1991 is still a valid and reliable approach to the data collection
logistics. Field operations can be optimised for time efficiency by using
project management techniques for planning survey networks including
leap-frog and synchronised movement logistic approaches.451
♦ Instrumentation to complete the same project today would most likely
include three or more dual frequency GPS receivers. This number of
receivers directly improves the network closure functionality by directly
containing a triangular figure for misclosure analysis purposes and
improved field operations logistics.452 By comparison, the 1991 survey
used two single frequency GPS receivers.
♦ Quality of Q.G.S. marks unknown/ not stated in Morrow’s paper.
Speculatively, the nature of this point is of medium positional uncertainty
for QGS marks used, thereby survey is relative to QGS mark. However, the
450ICSM, 2002, SP1 Standards and Practice for Control Surveys, Version 1.5 May 2002. Part A Section 4 page A-16 Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (Jan. 2003) 451 This assertion is supported by comparisons and ranking of GPS techniques made by Peter Large, 1999, GPS Control Network Design and Logistics for Linear Engineering Projects, Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited. pp.13. 452Of particular interest is the comments in section 5.2.3 Observation scheduling for GPS survey planning and 5.2.5 Logistical considerations. Rizo C., 1999, Principles and Practice of GPS Surveying, School of Geomatic Engineering, University of New South Wales. Section 5.2.3 & 5.2.5. Available on-line Internet http://www.gmat.unsw.edu.au/snap/gps/gps_survey/principles_gps.htm (accessed Dec. 2002)
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modern approach is such that all GPS surveys should be connected to the
state control where it is available, for the purposes of survey integration,
legal traceability and quality assurance.453 Fortunately, the state NR&M
have invested wisely in 100km geodetic infrastructure network with an
ongoing program of control densification.454
♦ No comparison to direct (traditional) EDMI lengths stated in original paper.
However, it is worth noting that adopting original bearing and distances
(three sides of large block) with one side GPS derived appears to provide
lower confidence level with approximately 1:4000 misclosure ratio (based
on the authors detailed calculations).
♦ Monuments aid to determine cadastral reinstatement rather than the sole
reliance on GPS derived measures (situation the same today and in 1991).
The collection of the location of cadastral boundary evidence has been
improved by GPS measurement technology and methods, but the
reinstatement process in weighting the evidence is still largely the same
situation. GPS technology has potentially reduced the human resources
required for a survey field party from two or three to one person depending
on the method proposed and security of instrumentation in rural projects.455
♦ Local AMG84 network distortions; MGA94 co-ordinates minimize this
aspect through distortion modelling and use of consistent software
processes as suggested through the Geocentric Datum Australia Technical
Manual.456
453 ICSM, 2002, SP1 Standards and Practice for Control Surveys, Version 1.5 May 2002. Part B Section 2.6.6.1 Network Design and Geometry page B-18 Available on-line Internet http://www.anzlic.org.au/icsm/publications/sp1/sp1.htm (Accessed Jan. 2003) 454 Cowie M., 1999, 'The Qld Geodetic Network – Adjusting to GDA94'. Proceeding of Survey’99 Congress, Queensland Institution of Engineering and Mining Surveyors Australia, Sunshine Coast, October. 455 This point of view is supported by works such as Hoogsteden C., Denys P., McDaid D., 1997, 'Cadastral surveys and the GPS option: Origin definition, time and cost comparisons for an urban cadastral survey'. Trans- Tasman Surveyor, vol.1, no.2 July, page 51. 456 GDA Technical Manual is available on-line Internet and provides links to State derived software for more precise distortion modelling when transforming planimetric position data to the new Geocentric Datum http://www.auslig.gov.au/ausgda/gdastrat.htm (accessed November 2001)
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
238
♦ Calculations for correcting projected distances derived from GPS methods
back to plain distances (scale factor 1 for cadastral surveys) appears to be
consistent with some overseas descriptions of case studies.457
♦ This comments section on comparison of approaches must provide the
qualification that the cadastral work or reinstatement is not in question, as
the measurement work undertaken to support the subdivision purposes
appears to most probably use the best practice at the time of survey. It is
reiterated that GPS measurement technology was at an infant stage in this
country in 1991 at the time of this project.
♦ ‘Position’ is not an easily recognised stand-alone quantity, as it is to the
informed landholder identifying the physical monuments on the ground
demonstrating the intent of the boundary intersection in a rural setting.
The co-ordinate collection technology employed using GPS techniques for this
specific application has shown some deficiency in the earlier survey by
comparison to today’s control survey practices and reductions. Changing
technology applied to the measurement sciences is occurring at rapid pace.
Dale (1999) foresees the potential for increased disputes as these GPS
measurement systems decrease in price. GPS is capable of producing a precision of measurement that is in excess of what is needed for [Rural] land titling or the resolution of boundary disputes. Although high precision surveys currently require more sophisticated technology and data processing than is available from high street shops, the trend is clear. There will be cheap GPS systems that will produce very precise survey measurements and this may in consequence increase the level of disputes between neighbours. In many jurisdictions, the re-location of property boundaries is decided on the basis of evidence in which marks on the ground take precedence over what may be recorded in abstract mathematical form – monuments make better evidence than measurements. As cheaper measurement systems become available this may be reversed and this could result in misunderstanding between neighbours.458
457 Londe M., 1998, ‘Guidelines for using GPS on Large Scale Cadastral Surveys (Wyoming & Nebraska)’, Proceedings of 1998 Trimble User Conference. Trimble Navigation Limited. pp.4. 458 Dale P., 1999, ‘Is Technology a Blessing or a Curse in Land Administration?’, Proceedings of UN-FIG Conference on Land Tenure and Cadastral Infrastructure for Sustainable Development, Melbourne, October 1999. page 3.
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
239
Gerdan (1991) performed an additional noteworthy study concerning GPS co-
ordinate collection techniques applied to rural property surveys. That study
presented findings in undertaking an early comparison between performing a
rural cadastral survey using traditional total station traverse with radiations and
the GPS kinematic techniques over a 30-hectare rural project site. The survey
consisted of 10 traverse points around a generally rectangular parcel with some
gums trees causing partial satellite obstruction to one traverse point. Gerdans’
findings concluded that: The emergence of the Global Positioning System (GPS) as a surveying tool has initiated a great deal of research into the possible applications of the system. This has attempted to highlight the GPS field and data reduction techniques required to operate in the stop/go kinematic mode of operation. The kinematic survey procedure has been successfully applied to a rural cadastral survey application. Comparisons between GPS and conventi[on]al measurements reveal survey differences between one to four centimetres. The standards presented are acceptable for Class D cadastral surveys. The GPS methods have been shown to be quicker than conventional techniques, and have the future potential to be a cost effective tool for rural cadastral surveying.459
From the comparison between techniques and methods explored for this
investigative study, it is clear that the application of a geodetic survey
technique to a cadastral application involving co-ordinate survey control is
being adapted to provide efficient rural cadastral surveys suitably recognised
by authorities. When geodetic survey techniques are applied to surveys on new
subdivisions they are demonstratively providing a means to improving the
integrity of spatially related property boundaries.
459 Gerdan, G.P., 1991, ‘Rural Cadastral Surveying with the GPS’, The Australian Surveyor, September, Vol.36 No.3, page 193.
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
240
A.6 Summary Much has been discussed and written in the last decade about the issue of legal
traceability of GPS measurements. How they could or should be traceable to
the appropriate Australian primary standard of measurement or recognised-
value standard of position has additionally been reviewed at some length in
chapter five.
Typically, cadastral surveys in urban areas are small in size and generally
enclose land of uniform slope. The well-established techniques of traversing
and radiation have been used to gather the required survey information. This
has meant that many surveys for cadastral purposes can be performed in a
matter of field hours using modern total station equipment fitted with legally
traceable EDMI.
In rural regions of Australia however, the terrain encountered is often
undulating and survey areas may cover tens to hundreds of hectares. The field
data-collection period for surveys in this type of environment can typically take
several days using conventional survey techniques with modern total station
and data-recorder technology. This somewhat lengthy observation period is
partially due to the nature of the survey technique used. Traversing and
radiation procedures are restricted to line-of-sight requirements between local
survey traverse stations. In large areas with undulating terrain a substantial
number of points may need to be occupied for traverse and boundary
occupation sampling (fence location).
GPS measurement systems are now capable to provide rapid, centimetre level
co-ordinate precisions by employing various techniques and double-occupation
(or greater) of points. The GPS measurement technique is not restricted by
line-of-sight requirements however, the survey area needs to contain a
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
241
minimum of overhead obstructions with generally clear topocentric view.460 In
many rural areas, the terrain is moderately clear and an open view of the sky is
generally available, even if the GPS antenna needs to be raised a number of
metres vertically above the ground monument to improve this topocentric
view.
GPS is but one of many tools for surveyors to use in digital data-collection in
the field. The field limitation of overhead obstructions highlights the need for
surveyors and other spatial professionals to integrate survey techniques to
achieve the most efficient surveying approach for the project at hand. The
amount of measurement technology integration between conventional and GPS
techniques will be dependent on the nature of the survey project and
specifications in suppling spatial information to the client and the community.
460This statement is supported by the comments of Kirk G., 1999, ‘Guide to Successful GPS RTK Surveying,’ Proceedings of 1999 Trimble User Conference. Trimble Navigation Limited. Page 1. AND from practical equipment testing at Pinjarra Hills contained in figure A.1 and previous GPS surveys conducted in Linthorpe Valley, Darling Downs.
Appendix A: Rural Cadastral Subdivision by GPS Techniques- Investigative Study
242
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