DESCRIPTION

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 

INPUT_MAP_vector_strength_NxN
and 
  INPUT_MAP_fisher_K_NxN
where N is the window size.

EXAMPLE

  # calculate roughness factor by search window = 5
  r.roughness.vector elevation=DEM slope=slope aspect=aspect window=5

SEE ALSO

r.mapcalc, r.slope.aspect

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. 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

AUTHORS

Carlos Henrique Grohmann - Institute of Energy and Environment, University of São Paulo, Brazil. (http://carlosgrohmann.com)
Helmut Kudrnovsky

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