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 strength.
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
# calculate roughness factor by search window = 5 r.roughness.vector elevation=DEM slope=slope aspect=aspect window=5
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. http://dx.doi.org/10.1016/S0169-555X(03)00164-8.
Grohmann, C.H., Smith, M.J. & Riccomini, C., 2011. Multiscale Analysis of Topographic Surface Roughness in the Midland Valley, Scotland. Geoscience and Remote Sensing, IEEE Transactions on, 49:1200-1213. http://dx.doi.org/10.1109/TGRS.2010.2053546
© 2003-2021 GRASS Development Team, GRASS GIS 7.8.6dev Reference Manual