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).
r.param.scale [-c] input=name output=name [slope_tolerance=float] [curvature_tolerance=float] [size=integer] [method=string] [exponent=float] [zscale=float] [--overwrite] [--verbose] [--quiet] [--qq] [--ui]
Example:
r.param.scale input=name output=name
grass.script.run_command("r.param.scale", input, output, slope_tolerance=1.0, curvature_tolerance=0.0001, size=3, method="elev", exponent=0.0, zscale=1.0, flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)
Example:
gs.run_command("r.param.scale", input="name", output="name")
Parameters
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)
Allowed values: 3-499
Default: 3
method=string
Morphometric parameter in 'size' window to calculate
Allowed values: 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
-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
--qq
Very quiet module output
--ui
Force launching GUI dialog
input : str, required
Name of input raster map
Used as: input, raster, name
output : str, required
Name for output raster map containing morphometric parameter
Used as: output, raster, name
slope_tolerance : float, optional
Slope tolerance that defines a 'flat' surface (degrees)
Default: 1.0
curvature_tolerance : float, optional
Curvature tolerance that defines 'planar' surface
Default: 0.0001
size : int, optional
Size of processing window (odd number only)
Allowed values: 3-499
Default: 3
method : str, optional
Morphometric parameter in 'size' window to calculate
Allowed values: elev, slope, aspect, profc, planc, longc, crosc, minic, maxic, feature
Default: elev
exponent : float, optional
Exponent for distance weighting (0.0-4.0)
Default: 0.0
zscale : float, optional
Vertical scaling factor
Default: 1.0
flags : str, optional
Allowed values: c
c
Constrain model through central window cell
overwrite: bool, optional
Allow output files to overwrite existing files
Default: False
verbose: bool, optional
Verbose module output
Default: False
quiet: bool, optional
Quiet module output
Default: False
superquiet: bool, optional
Very quiet module output
Default: False
DESCRIPTION
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
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.
EXAMPLE
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
TODO
Fix bug when `constrain through central cell' option selected. Create color tables for all output files (presently only on features).
REFERENCES
- 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
SEE ALSO
AUTHORS
Update to FP 3/2002: L. Potrich, M. Neteler, S. Menegon (ITC-irst)
SOURCE CODE
Available at: r.param.scale source code
(history)
Latest change: Friday Mar 07 07:39:48 2025 in commit e1e37d8