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<em>r.param.scale</em> extracts terrain parameters from a digital elevation model. Uses a
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multi-scale approach by fitting a bivariate quadratic polynomial to a given
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window size using least squares.
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<p>The module calculates the following parameters (terminology is from Wood,
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1996 with related terminology used in other GRASS modules listed in
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<i>elev</i>: Generalised elevation value (for resampling purposes at different
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<i>slope</i>: Magnitude of maximum gradient (steepest slope angle)</li>
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<i>aspect</i>: Direction of maximum gradient (steepest slope direction=flow direction)</li>
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<i>profc</i>: profile curvature (curvature intersecting with the plane
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defined by <i>Z</i> axis and maximum gradient direction). Positive values
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describe convex profile curvature, negative values concave profile
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<i>planc</i>: plan curvature (horizontal curvature, intersecting with
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the <i>XY</i> plane)</li>
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<i>longc</i>: longitudinal curvature (profile curvature intersecting
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with the plane defined by the surface normal and maximum gradient direction)</li>
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<i>crosc</i>: cross-sectional curvature (tangential curvature intersecting
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with the plane defined by the surface normal and a tangent to the contour
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- perpendicular to maximum gradient direction)</li>
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<i>maxic</i>: maximum curvature (can be in any direction)</li>
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<i>minic</i>: minimum curvature (in direction perpendicular to the direction
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of of maximum curvature)</li>
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<i>meanc</i> or mean curvature (average of maximum and minimum curvatures).</li>
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<i>feature</i>: Morphometric features: peaks, ridges, passes, channels, pits and planes</li>
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In <i>r.param.scale</i> the direction of maximum gradient (considered
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downslope) is stored as (West is 0 degree, East is +/- 180 degree):
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0..+180 degree from West to North to East</li>
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0..-180 degree from West to South to East</li>
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Note that the aspect map is calculated differently from
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<em><a href="r.slope.aspect.html">r.slope.aspect</a></em>.
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The next commands will create a geomorphological map of the Spearfish region:
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<div class="code"><pre>
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g.region raster=elevation.10m -p
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r.param.scale in=elevation.10m output=morphology param=feature size=9
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<img src="r_param_scale_morph.jpg" alt="r.param.scale generated geomorphological map"><br>
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<i>Geomorphological map of a subregion in the Spearfish (SD) area</i>
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Fix bug when `constrain through central cell' option selected. Create color
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tables for all output files (presently only on features).
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Wood, J. (1996): The Geomorphological characterisation of Digital Elevation
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Models. Diss., Department of Geography, University of Leicester, U.K.
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<br><a href="http://www.soi.city.ac.uk/~jwo/phd/">http://www.soi.city.ac.uk/~jwo/phd/</a>
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<a href="http://www.geog.le.ac.uk/jwo/research/LandSerf">LandSerf</a>
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that implements the same procedure
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<!-- not ported to GRASS 6 due to non-GPLness of numerical recipes.
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<i><a href="d.param.scale.html">d.param.scale</a></i>
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<a href="r.slope.aspect.html">r.slope.aspect</a>
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<a href="MAILTO:jwo@le.ac.uk">jwo@le.ac.uk</a>
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- <a href="http://www.geog.le.ac.uk/assist/index.html">ASSIST's home</a></address>
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<p>Update to FP 3/2002: L. Potrich, M. Neteler, S. Menegon (ITC-irst)
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<i>Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $</i>