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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