[GRASS-dev] [GRASS GIS] #2526: extend r.slope.aspect to compute the values at the edges
GRASS GIS
trac at osgeo.org
Sun Jan 4 10:37:39 PST 2015
#2526: extend r.slope.aspect to compute the values at the edges
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Reporter: hellik | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 7.1.0
Component: Raster | Version: svn-trunk
Keywords: slope | Platform: All
Cpu: All |
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taken from the ML
http://lists.osgeo.org/pipermail/grass-dev/2015-January/072779.html
{{{
Another way would be to modify r.slope.aspect to compute the values at the
edges - a second order polynomial min.square approximation
is used to estimate the derivatives in r.slope.aspect (you get the well
known differencing function when you do the math) and it can be used also
to compute the values at the edge cells, but I had no luck convincing
others that it is the right thing to do.
I believe that any reasonable estimate is better than the current
shrinking region (in r.flow we just propagate the same values to the
edges), but that does not seem to be the consensus.
Also, implementation for the edges is not straightforward because of how
GRASS works with rows, but a smart developer could certainly do it.
}}}
it would be nice that r.slope.aspect compute the values at the edges, at
least as an option. I agree that any reasonable estimate is better than
the current shrinking region.
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Ticket URL: <http://trac.osgeo.org/grass/ticket/2526>
GRASS GIS <http://grass.osgeo.org>
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