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Fieldwork: the role of validation in geo-information science

RS&GIS Integration Course (GRS-30806)

Lammert KooistraContact: Lammert.Kooistra@wur.nl

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Geo-information cycle

“real”

land use

validation error matrix

source: www.lgn.nl

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Solution: fieldwork

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Overview

Fieldwork assignment (lecture 1) Theory of validation Validation in practice: the validation plan The fieldwork assignment Case studies Available datasets and equipment Planning Role, communication & contact with coach

Writing a scientific paper (lecture 2)

Practical issues (lecture 3)

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(geo-spatial) model development cycle

source: Sargent (1998)

landscape openness

MODIS NDVI

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Definition of validation Modeling domain (GMP Manual Part 1 (p. 3-7)): validation is

used to check the suitability of the model to simulate an independent data set (i.e. not used in calibration)

RS domain (CEOS WGCV): validation is the process of assessing by independent means the quality of the data products derived from the system outputs (from Liang, 2004)

Spatial modeling domain (Sargent, 1998): substantiation that a computerized model within its domain of applicability possesses a satisfactory range of accuracy consistent with the intended application of the model

verification (Sargent, 1998): ensuring that the computer program of the computerized model and its implementation are correct

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Operational validity

Returns measure of accuracy Of interest for end-user Assessment of processing algorithms Determination of sources of uncertainty

source: Sargent (1998)

Operational validationclassification

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Example 1: landscape enclosure Comparison of spaciousness:

field and photograph observed calculated with model (topographic features)

source: Palmer&Roos (1998)

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Example 2: MODIS LAI

source: Tian et al., 2002

1. study area: savanna

2. sampling in1 x 1 km area

3. comparison of MODISbased LAI with field LAI

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Example 3: global land use

http://www.confluence.org

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Validation and scaling

Example of flux tower in the field (above) and distribution of RS based observation net-works over the globe (left)

Example of fieldwork activities: field spectroscopy, hemispherical camera, species composition

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Fieldwork assignment

Investigate role of validation in geo-information cycle based on a case study for the Achterhoek area. The final result of this assignment is an individual paper.

Activities: Introduction to case study (= spatial model) Preparation of validation plan Make field measurements Analyze results Write individual paper

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Case studies

Group 1: Validating visibility measures to estimate perceived landscape openness (Gerd Weitkamp)

Group 2: Remote sensing based mapping of biomass and canopy water content for natural grassland ecosystems (Lammert Kooistra)

Group 3: Sensing recreational use of the environment (Arend Ligtenberg)

Group 4: Characterization of vegetation roughness using 3D-GPS (John Stuiver)

Group 5: Remote sensing based monitoring of Natura2000 area Korenburgerveen (Harm Bartholomeus)

Group 6: Accuracy assessment of the LGN land cover data base for the Netherlands (Jan Clevers)

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Validation plan

Spatial model

Real world Validation plan

Fieldwork

Evaluation

Structured description of validation methodology for a specified spatial model and a specified domain of application

Descriptive, reproducible, from general to detailed http://eospso.gsfc.nasa.gov/validation/terraval.php http://www.daac.ornl.gov/DAAC/PI/bestprac.html

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Components of a validation plan

Which (geo-spatial) model Which (independent) variables Which quality parameter Which sampling scheme Which spatial and temporal extent Which (geo) data Which (field) instruments Which measurement protocols Which field forms

Schematic presentation of methodology in flow chart

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Validation plan: background and objective Which (spatial) model Which (independent) variable(s) will be

validated Which quality parameter: evaluation Formalize complete methodology in

flowchart

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Validation plan: sampling strategy

Which sampling scheme Which spatial and temporal extent

Locations Measurements in time Stratification Prior knowledge/data

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Validation plan: data and instrumentation

Which (geo) data Which (field) instruments

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Validation plan: implementation

Which measurement protocols Which field forms Preparation of (digital) field maps

During fieldwork: Store and back-up data First check of results in “field office”

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Available data and equipment

See website: http://webgrs.wur.nl/cgi/courses/grs30806/

Under Fieldwork/case studies

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Planning

Preparation in Wageningen: 3, 5 and 6 June: Introduction to case study Preparation of validation plan (incl., data and instruments) Feedback from coach

Fieldwork in Achterhoek: 8 June (19:00) – 13 June Arrival Sunday June 10 from 19:00 Reconnaissance study area + testing instruments Test measurement protocols Measurements according to validation protocol Check and first analysis of results Field presentation of results: feedback from coaches

Paper writing in Wageningen: 17 June – 27 June

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Role, communication & contact with coach Providing students with background information

and knowledge on topic Judge the validation plan during the preparation

week Assist and provide feedback during fieldwork week Judge results of field presentation and give

feedback If required assist students during elaboration of

results Judge the final result of case study: the individual

papers