r.tpi
Calculates the multiscale topographic position index
r.tpi input=name minradius=integer maxradius=integer steps=integer output=name [--overwrite] [--verbose] [--quiet] [--qq] [--ui]
Example:
r.tpi input=name minradius=1 maxradius=31 steps=5 output=name
grass.script.run_command("r.tpi", input, minradius=1, maxradius=31, steps=5, output, overwrite=False, verbose=False, quiet=False, superquiet=False)
Example:
gs.run_command("r.tpi", input="name", minradius=1, maxradius=31, steps=5, output="name")
Parameters
input=name [required]
Elevation
Input DEM from which to calculate mTPI
minradius=integer [required]
Smoothing neighborhood radius size (minimum)
Minimum neighborhood radius in cells for DEM smoothing
Default: 1
maxradius=integer [required]
Smoothing neighborhood radius size (maximum)
Maximum neighborhood radius in cells for DEM smoothing
Default: 31
steps=integer [required]
Number of scaling steps
Number of steps to use for DEM generalization between minradius and maxradius
Default: 5
output=name [required]
Multi-scale topographic position index
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--qq
Very quiet module output
--ui
Force launching GUI dialog
input : str, required
Elevation
Input DEM from which to calculate mTPI
Used as: input, raster, name
minradius : int, required
Smoothing neighborhood radius size (minimum)
Minimum neighborhood radius in cells for DEM smoothing
Default: 1
maxradius : int, required
Smoothing neighborhood radius size (maximum)
Maximum neighborhood radius in cells for DEM smoothing
Default: 31
steps : int, required
Number of scaling steps
Number of steps to use for DEM generalization between minradius and maxradius
Default: 5
output : str, required
Multi-scale topographic position index
Used as: output, raster, name
overwrite: bool, optional
Allow output files to overwrite existing files
Default: False
verbose: bool, optional
Verbose module output
Default: False
quiet: bool, optional
Quiet module output
Default: False
superquiet: bool, optional
Very quiet module output
Default: False
DESCRIPTION
r.tpicalculates a multiscale version of the Topographic Position Index (TPI) of Guisan et al. (1999). The TPI is calculated by averaging a DEM over a user-specified moving window size and subtracting the original DEM from the averaged version to get the residual. This has the effect of extracting finer-scale landforms from regional-scale relief. Positive TPI values represent ridges or hills, and negative TPI values represent valleys or pits.
Unlike the original TPI, r.tpi implements a multiscale version that calculates a standardized TPI over multiple neighborhood radii from minradius to maxradius, starting at the largest neighborhood size. For subsequent steps, the standardized TPI is updated with pixels where the absolute TPI values exceed the TPI values of the previous step. For large neighborhoods > 15, resampling is used rather than a focal function to generalize the DEM.
EXAMPLE
g.region raster=elevation@PERMANENT -a
r.tpi input=elevation@PERMANENT minradius=1 maxradius=25 steps=5 output=tpi
REFERENCES
Guisan, A., S. B. Weiss, A. D. Weiss 1999. GLM versus CCA spatial modeling of plant species distribution. Plant Ecology 143: 107-122
SEE ALSO
AUTHOR
Steven Pawley
SOURCE CODE
Available at: r.tpi source code
(history)
Latest change: Thursday Feb 20 13:02:26 2025 in commit 53de819