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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

r.param.scale example
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

r.geomorphon, r.slope.aspect

AUTHORS

Jo Wood - ASSIST's home

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