NAME
r.pi.index - Basic patch based indices
KEYWORDS
raster
SYNOPSIS
r.pi.index
r.pi.index help
r.pi.index [-a] input=name output=name keyval=integer method=string [title="phrase"] [--overwrite] [--verbose] [--quiet]
Flags:
- -a
- Set for 8 cell-neighbors. 4 cell-neighbors are default
- --overwrite
- Allow output files to overwrite existing files
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- input=name
- Raster map containing categories
- output=name
- Output patch-based result as raster map
- keyval=integer
- The value of the class to be analysed
- method=string
- Operation to perform on fragments
- Options: area,perimeter,shape,border,compactness,asymmetry,area-perimeter,fractal,ENN
- title="phrase"
- Title for resultant raster map
DESCRIPTION
r.fragment is a patch based fragmentation analysis package.
Computation of basic fragmentation indices can be accomplished.
Available options for the index to be computed for patches within
a certain class are: area (area), perimeter (perim), SHAPE (shape),
Border-Index (bor), Compactness (comp), Asymmetry (asym),
area-perimeter ratio (apr), fractal dimension (fract),
distance to euclidean nearest neighbour (ENN).
NOTES
The Nearest Neighbour Index (ENN) analyse the Euclidean Nearest
Neighbour to the first neighbouring patch. The output value is in pixel and can
be converted to a distance values using g.region resolution information.
r.pi.enn and r.fragment.fnn provide the same analysis concerning the
first nearest neighbour (NN), but are extended to the n-th NN. However due to
code construction does the r.pi.index distance analysis to first ENN perform faster.
Methods:
The method operators determine what algorithm is applied
on the patches.
r.pi.index
can perform the following operations:
Area
The Area computes the area of each patch.
Perimeter
The Perimeter computes the perimeter of each patch.
Area-Perimeter ratio
The Area-Perimeter ratio divides the patch perimeter by the area.
SHAPE Index
The SHAPE Index divides the patch perimete by the minimum perimeter
possible for a maximally compact patch of the corresponding patch area.
Border Index
The Border Index ....
Compactness Index
The Compactness Index ....
Asymmetry Index
The Border Index ....
Fractal Dimension Index
The Fractal Dimension Index ....
Nearest Neighbour Index
The Nearest Neighbour Index computes the Euclidean distance
to the first nearest neighbour patch.
EXAMPLE
Examples based on the North Carolina sample dataset are provided below. Indices are calculated for the landscape class 5 (forest).
set region settings to used landcover class map:
g.region rast=landclass96
r.pi.index input=landclass96 output=landclass96_forestclass5_area keyval=5 method=area
# improve colouring of resulting map:
r.colors landclass96_forestclass5_area col=bgyr
r.pi.index input=landclass96 output=landclass96_forestclass5_area keyval=5 method=area -a
r.pi.index input=landclass96 output=landclass96_forestclass5_ENN keyval=5 method=ENN -a
SEE ALSO
r.pi.enn,
r.pi.import,
r.pi.rectangle,
r.pi
BUGS
Landscapes with more than 10 000 individual patches might cause a memory
allocation error depending on your system.
AUTHORS
Programming: Elshad Shirinov
Scientific concept: Dr. Martin Wegmann
Department of Remote Sensing
Remote Sensing and Biodiversity Unit
University of Wuerzburg, Germany
Last changed: $Date$
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