GRASS GIS Manual: r.roughness.window.vector

NAME

r.roughness.window.vector

DESCRIPTION

r.roughness.window.vector calculates surface roughness in a moving-window, as the orientation of vectors normal to surface planes.

In this script surface roughness is taken as the dispersion of vectors normal to surface areas (pixels). Normal vectors are defined by slope and aspect.

This script will create several temporary maps, for the directional cosines in each direction (x,y,z), for the sum of these cosines and vector strenght.

The options compass, colatitude, xcos, ycosm and zcos are created as temporary files each time the script is run. If the user wants to create several map (with different window sizes, for instance), it is recommended to create those maps with r.mapcalc and use them as input:

r.mapcalc "compass    = if(aspect==0.,0.,if(aspect < 90., 90. - aspect, 360. + 90. - aspect))"
r.mapcalc "colatitude = 90. - slope"
r.mapcalc "xcos       = sin(colatitude)*cos(compass)"
r.mapcalc "ycos       = sin(colatitude)*sin(compass)"
r.mapcalc "zcos       = cos(colatitude)"

If the user does not specify the output maps names, they will be set to INPUT_MAP_vector_strength_NxN andINPUT_MAP_fisher_K_NxN
where N is the window size.

REFERENCES

Hobson, R.D., 1972. Surface roughness in topography: quantitative approach. In: Chorley, R.J. (ed) Spatial analysis in geomorphology. Methuer, London, p.225-245.

McKean, J. & Roering, J., 2004. Objective landslide detection and surface morphology mapping using high-resolution airborne laser altimetry Geomorphology, 57:331-351

AUTHOR

Carlos Henrique Grohmann

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