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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 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 11:23:43 -0700 (Sat, 15 Jul 2006) $
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