NAME

       r.param.scale  - Extracts terrain parameters from a DEM.
       Uses  a  multi-scale  approach  by  taking  fitting  quadratic  parameters  to any size window (via least
       squares).

KEYWORDS

       raster, geomorphology

SYNOPSIS

       r.param.scale
       r.param.scale help
       r.param.scale   [-c]   input=name    output=name     [s_tol=float]      [c_tol=float]      [size=integer]
       [param=string]   [exp=float]   [zscale=float]   [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -c
           Constrain model through central window cell

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input raster map

       output=name
           Output raster layer containing morphometric parameter

       s_tol=float
           Slope tolerance that defines a 'flat' surface (degrees)
           Default: 1.0

       c_tol=float
           Curvature tolerance that defines 'planar' surface
           Default: 0.0001

       size=integer
           Size of processing window (odd number only, max: 69)
           Default: 3

       param=string
           Morphometric parameter in 'size' window to calculate
           Options: elev,slope,aspect,profc,planc,longc,crosc,minic,maxic,feature
           Default: elev

       exp=float
           Exponent for distance weighting (0.0-4.0)
           Default: 0.0

       zscale=float
           Vertical scaling factor
           Default: 1.0

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

       jwo@le.ac.uk - ASSIST's home

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

       Last changed: $Date: 2009-04-02 23:17:56 -0800 (Thu, 02 Apr 2009) $

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