introduction to arcgis geostatistical analyst & fragstats represent the data explore the data...
Post on 19-Dec-2015
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Introduction to ArcGIS Geostatistical Analyst
& Fragstats
Represent the DataRepresent the Data
Explore the DataExplore the Data
Fit the ModelFit the Model
Perform DiagnosticsPerform Diagnostics
Compare ModelsCompare Models
Classify the OutputClassify the Output
Assess PatternAssess Pattern
ArcGIS
Using applied geostatistical methods to produce a continuous predictive surface from a discrete collection of sampled points
Using GIS to reclassify the predictive surface into functional classes or bins
Using landscape ecology metrics to assess and quantify the composition and configuration of the classification
Fragstats
Representing the DataRepresenting the Data
Converting data to GIS formatThe first step requires that the data be converted into a format that can be used by the GIS software
How are the data distributed?
Are there global trends in the data?
Exploring the DataExploring the Data
Are there outliers?
“The interpolation techniques used by the software work best with
normally distributed data….”
The semivariogram models the spatial dependence or autocorrelation between measured points. The semivariogram cloud shows ½ the squared difference
between all pairs of points as a function of separation distance (h).
Modeling the semivariogram is the key step between spatial description and spatial prediction.
Choosing the best model or continuous function to fit the empirical semivariogram helps ensure that the predicted values are as accurate as possible.
THE SEMIVARIOGRAM
Anisotropy
Things are more alike for longer distances in some directions than in other
directions
Directional Trends
When fitting a model to the semivariogram it is important to consider…
Set search neighborhood Assess the diagnostic stats
Model the semivariogramAccount for global trendsChoose the method
The ArcGIS Geostatistical Wizard uses a series of steps to calculate a best fit model & create a predictive surface
Fit the ModelFit the Model Perform DiagnosticsPerform Diagnostics
1 2 3
4 5
&
Which model is best?
Compare ModelsCompare Models
Reclassify predictive surface raster into categories or functional groups
Classify the OutputClassify the Output
Assess PatternAssess Pattern
Using metrics of landscape ecology, assess pattern of classified data using Fragstats…
Input = classified input grid Output = spreadsheet of selected metrics
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