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)
-
meanc or mean curvature (average of maximum and minimum curvatures).
-
featureMorphometric 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).
SEE ALSO
d.param.scale
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.geog.le.ac.uk/jwo/research/dem_char/thesis/index.html
AUTHOR
jwo@le.ac.uk
- ASSIST's home
Update to FP 3/2002: L. Potrich, M. Neteler, S. Menegon (ITC-irst)
Last changed: $Date$