r.param.scale1grass
Extracts terrain parameters from a dem. uses a multi-scale approach by taking fitting quadratic parameters to any size window (via least squares).
Usage
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]
Keywords
raster, geomorphology, terrain, elevation, landform
Overview
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):
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elev: Generalised elevation value (for resampling purposes at different scale)
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slope: Magnitude of maximum gradient (steepest slope angle)
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aspect: Direction of maximum gradient (steepest slope direction=flow direction)
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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.
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planc: plan curvature (horizontal curvature, intersecting with the XY plane)
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longc: longitudinal curvature (profile curvature intersecting with the plane defined by the surface normal and maximum gradient direction)
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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)
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maxic: maximum curvature (can be in any direction)
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minic: minimum curvature (in direction perpendicular to the direction of of maximum curvature)
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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.
Examples
The next commands will create a geomorphological map of the Spearfish sample dataset region:
g.region raster=elevation.10m -pr.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
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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
- •
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Java Code in LandSerf that implements the same procedure
Source code
Available at: r.param.scale source code (history)
Accessed: Monday Feb 24 17:50:45 2025
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Releases
10 releases since Debian 4.0 (Etch); the text changed 9 times.