 
Note: A new GRASS GIS stable version has been released: GRASS GIS 7.6, available here.
 Updated manual page: here
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]   [exponent=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
 
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.slope.aspect
jwo@le.ac.uk
- ASSIST's homeUpdate to FP 3/2002: L. Potrich, M. Neteler, S. Menegon (ITC-irst)
Last changed: $Date: 2016-12-11 10:03:35 -0800 (Sun, 11 Dec 2016) $
SOURCE CODE
Available at: r.param.scale source code (history)
Note: A new GRASS GIS stable version has been released: GRASS GIS 7.6, available here.
 Updated manual page: here
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GRASS Development Team,
GRASS GIS 7.2.4svn Reference Manual