r.li.patchdensity.1grass - Man Page
Calculates patch density index on a raster map, using a 4 neighbour algorithm
Keywords
raster, landscape structure analysis, patch index
Synopsis
r.li.patchdensity
r.li.patchdensity --help
r.li.patchdensity input=name config=name output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags
- --overwrite
Allow output files to overwrite existing files
- --help
Print usage summary
- --verbose
Verbose module output
- --quiet
Quiet module output
- --ui
Force launching GUI dialog
Parameters
- input=name [required]
Name of input raster map
- config=name [required]
Configuration file
- output=name [required]
Name for output raster map
Description
r.li.patchdensity calculates the "patch density index", the number of patches per square kilometer, as:
PD = Npatch / A
- with:
- A:sampling area size
- Npatch: number of patches
This index is calculated using a 4 neighbour algorithm, diagonal cells are ignored when tracing a patch.
Notes
Do not use absolute path names for the config and output file/map parameters. If the "moving window" method was selected in g.gui.rlisetup, then the output will be a raster map, otherwise an ASCII file will be generated in the folder C:\Users\userxy\AppData\Roaming\GRASS8\r.li\output\ (MS-Windows) or $HOME/.grass8/r.li/output/ (GNU/Linux).
A sample area of only NULL values is considered to have zero patches, that is, the result is always ⥠0.
Examples
To calculate patch density index on map my_map, using my_conf configuration file (previously defined with g.gui.rlisetup) and saving results in my_out, run:
r.li.patchdensity input=my_map conf=my_conf output=my_out
Example for Spearfish forest areas:
g.region raster=landcover.30m -p # extract forested areas: r.category landcover.30m r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43, 1, null())" # patch density (7x7 moving window defined in g.gui.rlisetup): r.li.patchdensity forests conf=movwindow7 out=forests_p_dens7 r.univar forests_p_dens7 d.rast.leg forests_p_dens7 r.to.vect forests out=forests feature=area d.vect forests type=boundary
Forest map (North Carolina sample dataset) example:
g.region raster=landclass96 -p r.mapcalc "forests = if(landclass96 == 5, 1, null() )" r.li.patchdensity input=forests conf=movwindow7 out=forests_patchdensity_mov7 # verify r.univar forests_patchdensity_mov7 r.to.vect input=forests output=forests type=area d.mon wx0 d.rast forests_patchdensity_mov7 d.vect forests type=boundary
See Also
r.li - package overview
g.gui.rlisetup
References
McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern analysis program for quantifying landscape structure. USDA For. Serv. Gen. Tech. Rep. PNW-351. (PDF)
Authors
Michael Shapiro - CERL (patch identification)
Markus Metz (statistics)
Source Code
Available at: r.li.patchdensity source code (history)
Accessed: Monday Sep 09 08:47:50 2024
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