## NAME

r.param.scale

## DESCRIPTION

r.param.scale extracts terrain parameters from a DEM. Uses a multi-scale approach by fitting a bivariate quadratic polynomial to a given window size using least squares.

The module calculates the following parameters (terminology is from Wood, 1996 with related terminology used in other GRASS modules listed in brackets):

- elev: Generalised elevation value (for resampling purposes at different scale)
- slope: Magnitude of maximum gradient (steepest slope angle)
- aspect: Direction of maximum gradient (steepest slope direction=flow direction)
- profc or profile curvature (curvature intersecting with the plane defined by Z axis and maximum gradient direction). Positive values describe convex profile curvature, negative values concave profile curvature.
- planc or plan curvature (horizontal curvature, intersecting with the XY plane)
- longc or longitudinal curvature (profile curvature intersecting with the plane defined by the surface normal and maximum gradient direction)
- crosc or cross-sectional curvature (tangential curvature intersecting with the plane defined by the surface normal and a tangent to the contour - perpendicular to maximum gradient direction)
- maxic or maximum curvature (can be in any direction)
- minic or minimum curvature (in direction perpendicular to the direction of of maximum curvature)
- feature: Morphometric features: peaks, ridges, passes, channels, pits and planes

## NOTES

In r.param.scale the direction of maximum gradient (considered downslope) is stored as (West is 0 degree, East is +/- 180 degree):

- 0..+180 degree from West to North to East
- 0..-180 degree from West to South to East

Note that the aspect map is calculated differently from r.slope.aspect.

## Still to do

Fix bug when `constrain through central cell' option selected. Create color tables for all output files (presently only on features).

## EXAMPLE

The next commands will create a geomorphological map of the Spearfish region:

    g.region rast=elevation.10m -p
    r.param.scale in=elevation.10m output=morphology param=feature size=9
    d.mon x0
    d.rast.leg morphology

Geomorphological map of a subregion in the Spearfish (SD) area

## SEE ALSO

Java Code in LandSerf that implements the same procedure

## REFERENCE

Wood, J. (1996): The Geomorphological characterisation of Digital Elevation Models. Diss., Department of Geography, University of Leicester, U.K.
online at:
http://www.soi.city.ac.uk/~jwo/phd/

## AUTHOR

Update to FP 3/2002: L. Potrich, M. Neteler, S. Menegon (ITC-irst)

Last changed: $Date: 2009-04-03 09:17:56 +0200 (Fri, 03 Apr 2009) $

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