NAME

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

Usage:

r.param.scale [-c] in=name out=name [s_tol=value] [c_tol=value] [size=value] [param=name] [exp=value] [zscale=value]
 

Flags:

-c Constrain model through central window cell

Parameters:

 in Raster surface layer to process

 out Output raster layer containing morphometric parameter

 s_tol Slope tolerance that defines a `flat' surface (degrees)
default: 1.0

 c_tol Curvature tolerance that defines `planar' surface
default: 1.0

 size Size of processing window (odd number only)
default: 3

 param Morphometric parameter to calculate
options: elev,slope,aspect,profc,planc,longc,crosc,minic,maxic, feature
default: elev

 exp Exponent for distance weighting (0.0-4.0)
default: 0.0

 zscale Vertical scaling factor
default: 1.0

 

r.param.scale can calculate the following:

 elev: Generalised elevation value.

 slope: Maximum gradient at a point.

 aspect: Direction of maximum gradient.

 profc: Profile convexity (vertical in direction of steepest slope).

 planc: Plan convexity (contour curvature).

 crosc: Cross sectional convexity (tangent to contours, downslope).

 longc: Longitudinal convexity (perpendicular to contours downslope).

 minic: Minimum convexity.

 maxic: Maximum convexity.

 features: Morphometric features:
                  peaks, ridges, passes, channels, pits and planes.
 

HISTORY

Modified to include constrained fitting. 
Jo Wood, April, 1995 
-------
Modified to include weighting matrix and double precision arithmetic.
Jo Wood, 9th May, 1995.
-------
Modified to include two separate tolerance values for feature detection.
Jo Wood, 23rd May, 1995.

Still to do

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

SEE ALSO

d.param.scale

See also Java Code in LandSerf that implements the same procedure 


jwo@le.ac.uk

ASSIST's home

REFERENCE

Wood, J. (1996): The Geomorphological characterisation of Digital Elevation Models. Diss., Department of Geography, University of Leicester, U.K.
online at:
www.geog.le.ac.uk/jwo/research/dem_char/thesis/index.html