[GRASS-user] r.shaded.relief question

Rich Shepard rshepard at appl-ecosys.com
Wed Jan 27 12:23:13 EST 2010

On Tue, 26 Jan 2010, Rich Shepard wrote:

>  Feeling irrationally exuberant that I might be able to quickly move on to
> hydrological modeling, I just tried running r.shaded.relief on the same
> raster DEM map used for the slopes, aspects, and curvatures. No joy. the
> relief map looks like the earlier slope and aspect ones: vertical bands of
> horizontal static.

   Got this fixed: it was incorrect region resolution.

   Now I have a question about the results. The source DEM has the highest
area in the southeast corner and the main stream drains northwest to the
confluence with a large river. The shaded relief map, however, does not
reflect this topography. Both maps have a resolution of 10m.

   On the shaded relief map, the drainage basin head appears as flat as the
confluence area.

   Why might I see results like this? Do I need to interpolate the source DEM
to a finer resolution before running r.shade.relief?

Suggestions needed,


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