HAMILTON COUNTYHAMILTON COUNTY

GEODETIC CONTROL GEODETIC CONTROL

Indiana GIS Indiana GIS ConferenceConference

February 19-20, 2008February 19-20, 2008

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INTRODUCTIONSINTRODUCTIONS

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Darren Wilson, GISPDarren Wilson, GISP

- GIS Specialist with the Surveyor’s - GIS Specialist with the Surveyor’s

Office since 1999Office since 1999

Val Swift, GISPVal Swift, GISP

- GIS Administrator with the Surveyor’s - GIS Administrator with the Surveyor’s

Office since 1993Office since 1993

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Kenton C. Ward, CFMKenton C. Ward, CFM - Hamilton County Surveyor since- Hamilton County Surveyor since 19771977

Joseph Mullins, LSJoseph Mullins, LS - Survey Manager with Surveyor’s- Survey Manager with Surveyor’s Office since September 2007Office since September 2007

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Gary WardGary Ward - Section Corner Technician since- Section Corner Technician since November 2006November 2006

Steve FesmireSteve Fesmire - Survey Technician since January- Survey Technician since January 20002000

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A system of horizontal and/or vertical control stations that have been established and adjusted by geodetic methods and in which the shape and size of the earth (geoid) have been considered in position computations.

A network of carefully measured points that can be used as a reference for other surveys or to establish or measure accuracy in map making.

A network of points spread across the landscape where sturdy monuments have been placed in the ground, along with a high-accuracy positional value for each point. By referencing field survey measurements to such a network, the resulting survey data can be more accurately gathered.

HC DEFINITION(S)DEFINITION(S)Geodetic Geodetic ControlControl

SECTION CORNERSECTION CORNER PERPETUATION PERPETUATION

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- The Land Ordinance of 1785 created the Rectangular Public

Land Survey System (PLSS) - Section-Township-Range System

- Restoration/maintenance of section corners became the

responsibility of the local or county surveyor

- Today Administration of Section Corners are governed by

Indiana Code 36-2-12-11

SECTION CORNERSECTION CORNER PERPETUATION PERPETUATION

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- Hamilton County has a total of approximately 7,225 “corners”

- ie section corners, ¼ corners, 1/16 corners, center of

sections

- The Surveyor’s Office maintains approximately 1,700 section corners

HC16 Survey Townships

9 Full Townships7 Partial TownshipsT17N – R3ET17N – R4ET17N – R5ET17N – R6E

T18N – R3ET18N – R4ET18N – R5ET18N – R6E

T19N – R3ET19N – R4ET19N – R5ET19N – R6E

T20N – R3ET20N – R4ET20N – R5ET20N – R6E

HCwww.co.hamilton.in.us

Surveyor’s Documents for Download PageOO

RR

www.co.hamilton.in.us/page.asp?id=3121

Department Directory – Surveyor’s Office Page

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PRE-2007PRE-2007

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Linked using

bookmarks

Numbered using an alph-numeric

grid system

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MISSING STATEPLANE COORDINATEINFORMATION

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NO GIS LAYERNO GIS LAYER

ONLY SCANNED PDF’sONLY SCANNED PDF’s

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SUMMER 2007SUMMER 2007

- GPS Base Station came online in 2003 - Located on top of the Govt & Jud Ctr, downtown

Noblesville - Part of the Midwest RTK VRS Network

HC SUMMER 2007 cont.SUMMER 2007 cont.

- “Permanent” Part-time Section Corner Technician hired

- Gary Ward working 30 hrs/wk

- Revised the index sheet for the Section Corner Records

- Created new Corner Record Sheet

- Established new standards for field work

- Created new Geodetic Control GIS Layer

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SUMMER 2007 SUMMER 2007 cont.cont.

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THE RESULT?THE RESULT?

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NEW CORNER RECORD

INDEX FOR ALL

TWP PDF’s

Corner Record Sheet linked to triangle on index

CLEANER LOOK

HCIMPROVED MAP

STATE PLANE COORDINATES

HISTORICAL DOCUMENTATIO

N

COMMON CORNER INFORMATION IF APPLICABLE

NEW CORNER RECORD

SHEET

HCNEW PRE-CON

CORNER RECORD

SHEET

MONUMENT NOT TIED

DOWN

STATE PLANE COORDINATES

HISTORICAL DOCUMENTATIO

N

HCNEW GIS

LAYER CREATED

WITH ArcGIS

Currently 364 Points - 327 Finished Points - 37 Pre-Con Points

HC ATTRIBUTESATTRIBUTES

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““X & Y” X & Y” ATTRIBUTESATTRIBUTES

- Points created in the .shp file by using the SKETCH TOOL and

the “Absolute X,Y” Command1. SKETCH TOOL

2. RIGHT-CLICK AND SELECT “ABSOLUTE X,Y” OR F6

- X and Y Points are then manually typed into the attributes

table

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““PRE-CONPRE-CON” ” ATTRIBUTEATTRIBUTE

- Using a simple identifier, in this case a “Y”, allows you to differentiate between different types of points

RED TRIANGLE FOR FINISHED

PTSBLUE TRIANGLE-

WAITING ON MONUMENTATIO

N FROM THE STATE

YELLOW TRIANGLE FOR

PRE-CON PTS

COUNTS FOR QC

HC““TIE SHEETS” TIE SHEETS”

ATTRIBUTEATTRIBUTEhttp://www.co.hamilton.in.us/upload/images/survey/TieSheets/18050103.pdf

- Simple path set up as a hyperlink in the attribute table

- Two types of hyperlinks: Field-based and Dynamic

- Field-based is set up in the attribute table while dynamic

allows you to specify a hyperlink directly to the feature in

your map

- We’ve chosen to utilize the Field-Based hyperlink

HC““TIE SHEETS” TIE SHEETS”

ATTRIBUTEATTRIBUTE- Field Calculator is used to fill in this field of the

attribute table

HC““TIE SHEETS” TIE SHEETS”

ATTRIBUTEATTRIBUTE

- The PDF resides on Hamilton County’s own web server

- Anyone who downloads this GIS layer from the county’s

website will have access to the Corner Record Sheet as long

as they have internet access and Adobe Acrobat

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““IDname” IDname” ATTRIBUTEATTRIBUTE

IN02_T18NR05E01_08- This attribute was created so we could participate in

the Web Based - Tie Card Project

Three County Tie Card Layers are complete and in maintenance:

NEWTON CO.

BARTHOLOMEW CO.

JENNINGS CO.

For more information go to:www.in.gov/igic/projects/tiecard/

index.html

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““IDname” IDname” ATTRIBUTEATTRIBUTE

- The committee members for the Tie Card Project developed

a file naming convention that can be used statewideIN02_T18NR05E01_08

- Instead of changing our section corner numbering system

we added a field in the attribute table

STATE NAME AND PRIME

MERIDIAN IN02

TOWNSHIP NUMBER AND

DIRECTION T18N

RANGE NUMBER AND

DIRECTIONR05E

GRID NUMBER08

SECTION NUMBER01

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““IDname” IDname” ATTRIBUTEATTRIBUTE

- Cor_Num = 18050103 - Hamilton County’s Corner numbering system is

based on Marion County’s system

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““IDname” IDname” ATTRIBUTEATTRIBUTE

- We must convert the Cor_Num attribute (18050103) to the

IDname attribute (IN02_T18NR05E01_08)

GRID NUMBERING HAMILTON COUNTY CORNER NUMBERING SYSTEM

HC““TIE SHEETS” TIE SHEETS”

ATTRIBUTEATTRIBUTE- Use Field Calculator to create IDname attribute

- Expression:"IN02_T" + mid([Cor_Num],1,2) + "NR" +

mid([Cor_Num],3,2) + "E" + mid([Cor_Num],5,2) + "_" + mid([Cor_Num],7,2)

- The only thing left out is the conversion of the Position Number to the Grid Number - Right now that is manually entered

HC BENEFITSBENEFITS- Geodetic control networks support surveying,

engineering, and GIS applications throughout Hamilton County

- The devlopment of a modern digital control network is a

form of basic infrastructure (much like roads or utilities) needed to support current and future needs

- Creates a common, consistent, and accurate surveyed reference system

- Provides surveyors, engineers, etc. with a referenced coordinate system for new projects

HC BENEFITSBENEFITS- With an improved, digital geodetic control network, relationships to other GIS layers can be shown with

more confidence and reliability

- Finally, accurate information is the key to making informed

decisions. With an updated, digital geodetic control network

forming the basis of survey and GIS data, the quality of all

analysis and decision making has the chance to improve

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SO WHAT’S LEFT TO SO WHAT’S LEFT TO DO?DO?

HC- Update the remaining 1,336 section corner records and

include them in the GIS layer

- Have Corner Record Sheets created in a CAD or GIS software

- Download points directly from data collectors into ArcGIS

- Include some IF/THEN statements into the expression for the

IDname attribute so the Position Numbers won’t have to be

manually converted to the Grid Numbers for the Tie Card

Project

- Include our data on the Indiana GIS Atlas for the Web Based-

Tie Card Project

IN THE FUTURE…IN THE FUTURE…

HC- Once all 1,700 Section Corner Records are updated and

in the GIS layer, replace the Township PDF Section Corner records with an Online GIS layer in the Hamilton

County Online Maproom

IN THE FUTURE…IN THE FUTURE…

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QUESTIONSQUESTIONS

CONTACT CONTACT INFORMATIONINFORMATION

Hamilton County Surveyor’s Office online at

http://www.co.hamilton.in.us/departments.asp?id=2200 via email at surveyor@co.hamilton.in.us by phone at 776-8495