Centre for Geo-information Fieldwork: the role of validation in geo- information science RS&GIS...
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Transcript of Centre for Geo-information Fieldwork: the role of validation in geo- information science RS&GIS...
Centre for Geo-information
Fieldwork: the role of validation in geo-information science
RS&GIS Integration Course (GRS-30806)
Lammert KooistraContact: [email protected]
Centre for Geo-information
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