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:
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: 2009-04-03 09:17:56 +0200 (Fri, 03 Apr 2009) $
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