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, terrain, elevation, landform

SYNOPSIS

       r.param.scale
       r.param.scale --help
       r.param.scale       [-c]       input=name       output=name        [slope_tolerance=float]
       [curvature_tolerance=float]      [size=integer]      [method=string]      [exponent=float]
       [zscale=float]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -c
           Constrain model through central window cell

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name [required]
           Name of input raster map

       output=name [required]
           Name for output raster map containing morphometric parameter

       slope_tolerance=float
           Slope tolerance that defines a ’flat’ surface (degrees)
           Default: 1.0

       curvature_tolerance=float
           Curvature tolerance that defines ’planar’ surface
           Default: 0.0001

       size=integer
           Size of processing window (odd number only)
           Options: 3-499
           Default: 3

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

       exponent=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  digital  elevation  model.  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:  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: plan curvature (horizontal curvature, intersecting with the XY plane)

           •   longc:  longitudinal  curvature  (profile  curvature  intersecting  with the plane
               defined by the surface normal and maximum gradient direction)

           •   crosc: 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: maximum curvature (can be in any direction)

           •   minic: 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.

EXAMPLE

       The next commands will create a geomorphological  map  of  the  Spearfish  sample  dataset
       region:
       g.region raster=elevation.10m -p
       r.param.scale in=elevation.10m output=morphology method=feature size=9
       Figure: Geomorphological map of a subregion in the Spearfish (SD) area

TODO

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

REFERENCES

           •   Wood, J.  (1996):  The  Geomorphological  characterisation  of  Digital  Elevation
               Models. Diss., Department of Geography, University of Leicester, U.K
               online at: http://hdl.handle.net/2381/34503

           •   Java Code in LandSerf that implements the same procedure

SEE ALSO

        r.geomorphon, r.slope.aspect

AUTHORS

       jwo@le.ac.uk - ASSIST’s home

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

       Last changed: $Date: 2017-11-03 17:43:02 +0100 (Fri, 03 Nov 2017) $

SOURCE CODE

       Available at: r.param.scale source code (history)

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       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual