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r.param.scale

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r.param.scale: Extracts terrain parameters from a DEM. Uses a multi-scale approach by taking fitting quadratic parameters to any size

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: //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: 2009-04-03 09:17:56 +0200 (Fri, 03 Apr 2009) $ Full index (C) 2003-2010 GRASS Development Team R.PARAM.SCALE(1)
 
 
 

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