GRASS GIS manual: r.li.edgedensity

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NAME

r.li.edgedensity - Calculates edge density index on a raster map, using a 4 neighbour algorithm

KEYWORDS

raster, landscape structure analysis, patch index

SYNOPSIS

r.li.edgedensity
r.li.edgedensity help
r.li.edgedensity map=name conf=name output=name [patch_type=string] [--overwrite] [--verbose] [--quiet]

Flags:

--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

map=name: Name of input raster map
conf=name: Configuration file
output=name: Name for output raster map
patch_type=string: The value of the patch type; It can be integer, double or float; it will be changed in function of map type

DESCRIPTION

r.li.edgedensity calculates:

the density of all edges of patch type k , or
the density of all edges in the sampling area if k is not specified,

with:

k: patch type
m: number of patch types
n: number of edge segments of patch type k
eik :total edge length in the landscape involving patch type k
Area: total landscape area

The unit is meters per hectare.

NOTES

Do not use absolute path names for the config and output file/map parameters. If the "moving window" method was selected in r.li.setup, then the output will be a raster map, otherwise an ASCII file will be generated in the folder C:\Users\userxy\.r.li\output\ (MS-Windows) or $HOME/.r.li/output/ (GNU/Linux).

If the input raster map contains only NULL values then r.li.edgedensity consider to have 0 patches.
If area is 0 r.li.edgedensity returns -1; this is only possible if input raster is masked. If you want to change these -1 values to NULL, run subsequently on the resulting map:

r.null setnull=-1 map=my_map

after index calculation.

EXAMPLES

To calculate the edge density index on map my_map, using my_conf configuration file (previously defined with r.li.setup) and saving results in my_out, run:

r.li.edgedensity map=my_map conf=my_conf output=my_out

To calculate edge density index of patch_type 34, using "my_conf" configuration file and on map "my_map", saving results in "my_out" file run:

r.li.edgedensity map=my_map conf=my_conf output=my_out patch_type=34

Forest map (Spearfish sample dataset) example:

g.region rast=landcover.30m -p
r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43,1,null())"
r.li.edgedensity map=forests conf=movwindow7 out=forests_edgedens_mov7
r.univar forests_edgedens_mov7

Forest map (North Carolina sample dataset) example:

g.region rast=landclass96 -p
r.mapcalc "forests = if(landclass96 == 5, 1, null() )"
r.li.edgedensity map=forests conf=movwindow7 out=forests_edgedensity_mov7

# verify
r.univar forests_edgedensity_mov7
r.to.vect input=forests output=forests feature=area
d.mon x0
d.rast forests_edgedensity_mov7
d.vect forests type=boundary

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

Serena Pallecchi student of Computer Science University of Pisa (Italy).
Commission from Faunalia Pontedera (PI), Italy (www.faunalia.it)
Markus Metz

Last changed: $Date: 2014-10-19 14:32:22 -0700 (Sun, 19 Oct 2014) $

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