r.param.scale(1grass) GRASS GIS User's Manual r.param.scale(1grass)
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, terrain, elevation, landform
SYNOPSIS
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] [expo-
nent=float] [zscale=float] [--overwrite] [--help] [--verbose]
[--quiet] [--ui]
Flags:
-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
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)
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
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 direc-
tion=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 con-
cave 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 gradi-
ent direction)
• crosc: cross-sectional curvature (tangential curvature inter-
secting with the plane defined by the surface normal and a tan-
gent to the contour - perpendicular to maximum gradient direc-
tion)
• maxic: maximum curvature (can be in any direction)
• minic: minimum curvature (in direction perpendicular to the di-
rection of of maximum curvature)
• feature: Morphometric features: peaks, ridges, passes, chan-
nels, pits and planes
NOTES
In r.param.scale the direction of maximum gradient (considered downs-
lope) 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 Digi-
tal Elevation Models. Diss., Department of Geography, Univer-
sity 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
jwo@le.ac.uk - 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)
Accessed: unknown
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GRASS 7.8.7 r.param.scale(1grass)
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