r.param.scale(1)

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

KEYWORDS
raster

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]

  Flags:

-c  Constrain model through central window cell

--overwrite

  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 morphology map of the Spearfish region:
g.region rast=elevation.10m -p
r.param.scale in=elevation.10m output=morphology param=feature

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: 2006/07/15 18:23:43 $

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