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NAME

r.vector.ruggedness - Vector Ruggedness Measure

KEYWORDS

SYNOPSIS

r.vector.ruggedness
r.vector.ruggedness --help
r.vector.ruggedness elevation=name[,name,...] [size=integer[,integer,...]] output=name[,name,...] [slope=name] [aspect=name] [nprocs=integer] [--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:

elevation=name[,name,...] [required]
DEM Raster Input
GRASS raster elevation map
size=integer[,integer,...]
Size of neighbourhood
Size of neighbourhood to calculate the vector dispersion over. Multiple sizes are accepted to more efficiently calculate the VRM over different scales.
Default: 3
output=name[,name,...] [required]
Vector Ruggedness Measure Output
Name for output raster map(s)
slope=name
Optional slope raster map
Optional slope raster map. If not supplied, then a slope map will be calculated internally.
aspect=name
Optional aspect raster map
Optional aspect raster map. If not supplied, then an aspect map will be calculated internally.
nprocs=integer
The maximum number of cores to use for multiprocessing
The maximum number of cores to use for multiprocessing. -1 uses all cores, -2 uses n_cores-1 etc.
Default: -1

Table of contents

DESCRIPTION

r.vector.ruggedness represents a measurement of terrain ruggedness based on the methodology conceived by Sappington et al. (2007). The measure is calculated by decomposing slope and aspect into 3-dimensional vectors, and calculating the resultant vector magnitude within a user-specified moving window size using r.neighbors. The user can specify neighborhood size to measure ruggedness across larger scales. Neighborhood operations are performed using a rectangular window shape.

MULTI-SCALE CALCULATION

The r.vector.ruggedness tool provides an efficient approach of calculating the Vector Ruggedness Measure over multiple window sizes. The size argument accepts multiple answers (as a comma separated list), which will cause the tool to reuse the same slope, aspect and vector calculations, and apply them to the neighborhood operations that calculate the vector magnitudes. By default, both the calculation of the vectors and the vector magnitudes, including over different window sizes is performed in parallel using all available cores. To restrict parallel processing, the nprocs argument can be changed to use a smaller number of processing cores. When multiple sizes are used, the output raster name is appended with the window size. Optionally, pre-calculated slope and aspect maps (in degrees) can be used in the slope and aspect arguments to save computational time if the maps are already available.

NOTES

This script was adapted from the original Sappington et al. (2007) script.

EXAMPLE

The examples are to be executed using the GRASS GIS sample North Carolina data set. To calculate the Vector Ruggedness Measure using a single neighborhood size:

    r.vector.ruggedness elevation=elevation size=3 output=vrm

For efficient calculations of the Vector Ruggedness Measure over multiple neighborhood sizes, the slope, aspect and their x, y, z vectors will be reused during the calculation. The output name will be appended with the neighborhood size in order to identify the output maps:

    r.vector.ruggedness elevation=elevation size=3,5,7,9,11 output=vrm

REFERENCES

Sappington, J.M., K.M. Longshore, and D.B. Thomson. 2007. Quantifying Landscape Ruggedness for Animal Habitat Analysis: A case Study Using Bighorn Sheep in the Mojave Desert. Journal of Wildlife Management. 71(5): 1419 -1426.

SEE ALSO

r.mapcalc, r.neighbors

AUTHOR

Steven Pawley

SOURCE CODE

Available at: r.vector.ruggedness source code (history)


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