[GRASSLIST:2323] Removing a section of a raster map

Rich Shepard rshepard at appl-ecosys.com
Wed Aug 8 16:42:55 EDT 2001

  I've struggled with this for most of today and believe that it should not
be this difficult. Here's the scenario:

  On my comprehensive DEM raster map, I have a little protrusion on the
upper, left side (see attached 'dem.jpg') that was an unintended addition
when I fixed some holes using r.surf.idw. Now I want to get rid of that
extra group of cells, but I cannot.

  I've used r.reclass after zooming in to that region, and saving what I
thought would be only that region in the output map. Then I converted the
reclass table to a raster map using r.mapcalc and patched it back, thinking
that the NULL values would replace the elevation values. Wrong.

  r.mask works on cells only _within_ the mask. I would like to mask that
group off and remove it.

  As I wrote, I've spent several hours on this (and a few long distance
phone calls) and it's still there. I don't want those edge values used when
I run r.contour or do any terrain analyses.

  How can I clip this unwanted addition off the dem raster map?



Dr. Richard B. Shepard, President

                       Applied Ecosystem Services, Inc. (TM)
            2404 SW 22nd Street | Troutdale, OR 97060-1247 | U.S.A.
 + 1 503-667-4517 (voice) | + 1 503-667-8863 (fax) | rshepard at appl-ecosys.com
                 Making environmentally-responsible mining happen.
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