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).
raster, geomorphology, terrain, elevation, landform
r.param.scale
r.param.scale --help
r.param.scale [-c] input=name
output=name [slope_tolerance=float]
[curvature_tolerance=float] [size=integer]
[method=string] [exponent=float]
[zscale=float] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
- -c
-
Constrain model through central window cell
- --overwrite
-
Allow output files to overwrite existing files
- --help
-
Print usage summary
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
- --ui
-
Force launching GUI dialog
- input=name [required]
-
Name of input raster map
- output=name [required]
-
Name for output raster map containing morphometric parameter
- slope_tolerance=float
-
Slope tolerance that defines a ’flat’ surface (degrees)
Default: 1.0
- curvature_tolerance=float
-
Curvature tolerance that defines ’planar’ surface
Default: 0.0001
- size=integer
-
Size of processing window (odd number only)
Options: 3-499
Default: 3
- method=string
-
Morphometric parameter in ’size’ window to calculate
Options: elev, slope, aspect, profc, planc, longc, crosc, minic, maxic,
feature
Default: elev
- exponent=float
-
Exponent for distance weighting (0.0-4.0)
Default: 0.0
- zscale=float
-
Vertical scaling factor
Default: 1.0
r.param.scale extracts terrain parameters from a digital elevation model.
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: 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: plan curvature (horizontal curvature, intersecting with the
XY plane)
- longc: longitudinal curvature (profile curvature intersecting with
the plane defined by the surface normal and maximum gradient
direction)
- crosc: 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: maximum curvature (can be in any direction)
- minic: minimum curvature (in direction perpendicular to the
direction of of maximum curvature)
- feature: Morphometric features: peaks, ridges, passes, channels,
pits and planes
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.
The next commands will create a geomorphological map of the Spearfish sample
dataset region:
g.region raster=elevation.10m -p
r.param.scale in=elevation.10m output=morphology method=feature size=9
Figure: Geomorphological map of a subregion in the Spearfish (SD) area
Fix bug when `constrain through central cell’ option selected. Create
color tables for all output files (presently only on features).
- Wood, J. (1996): The Geomorphological characterisation of Digital
Elevation Models. Diss., Department of Geography, University of Leicester,
U.K
online at: http://hdl.handle.net/2381/34503
- Java Code in LandSerf that implements the same procedure
r.geomorphon, r.slope.aspect
jwo@le.ac.uk - ASSIST’s home
Update to FP 3/2002: L. Potrich, M. Neteler, S. Menegon
(ITC-irst)
Available at: r.param.scale source code (history)
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