Patch Analyst
What it is
How it works
What it does
Indices in Patch Analyst
Versions
Patch Analyst is a tool for quantifying landscape structure
that can be downloaded off the Internet from http://www.cnfer.on.ca/SEP/patchanalyst/
Patch Analyst is a modified version of FRAGSTATS which
has been developed to work specifically within ArcView GIS. It consists
of a series of programs written in Avenue and C.
Patch Analyst can work on vector (shape) or raster (grid)
data structures (themes within ArcView). The spatial statistics within
Patch Analyst are applied to the two classified videography images, which
can be put into ArcView as themes in grid (raster) format.
Once Patch Analyst has been added as an ArcView extension,
it is activated by clicking on 'Patch' in the ArcView menus and selecting
the 'Spatial Statistics' option. The result of selecting the 'Spatial
Statistics' option is that a dialogue box is opened that contains statistics
inputs and selections. This allows the user to select the theme upon which
they want the statistics to operate and also the type of statistics.
Patch Analyst allows the data to be analysed within
three levels of hierarchy.
- Landscape relates
to all the patches, polygons, contiguous cells or shapes in a view or
theme.
- Classes relate
to all the patches, polygons, contiguous cells or shapes in a theme,
view or landscape that have the same value for a given attribute.
- Patches relate
to the individual polygons or contiguous set of cells or shapes. Each
patch has a separate record or row in the theme attribute table.
Indices that can be calculated in Patch Analyst include:
Area Metrics
- Class area
- Landscape area
Patch density and size metrics
- Number of patches
- Mean patch size
- Median patch size
- Patch size standard deviation
- Patch size coefficient of variance
Edge metrics
- Total edge
- Edge density
- Mean patch edge
- Contrasted weighted edge
Shape metrics
- Mean perimeter-area ratio
- Mean shape index
- Area weighted mean shape index
- Mean patch fractal dimension
- Area weighted mean patch fractal dimension
Look up the glossary
for more information on these indices
There are two versions
of Patch Analyst:
- a vector only version
- a vector and raster version
The vector and raster version requires ArcViews spatial
analyst extension. These programs have been written to make landscape
indices an extension to ArcView's spatial analyst functionality. Patch
analyst has been developed by the Sustainable Forest Management Network
(NCE) and the Centre for Northern Forest Ecosystem Research (OMNR) in
the USA (Elkie
et al., 1999).
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Using Patch Analyst |
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Read the Kidman
Springs case study. Do you think that the patch statistics applied
using Patch Analyst and ArcView give a useful description of patterning
in this landscape? How effective would the description be without
it? |
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