[GRASS-user] cutting issue (again): r.mapcalc vs. r.resample

Achim Kisseler ak7 at jupiter.uni-freiburg.de
Mon Jan 25 17:41:34 EST 2010


Did you do:
g.copy rast=boundary_raster,MASK
or alternatively:
r.mask input=boundary_raster -o
(-o for overwrite)
?





Tim Michelsen schrieb:
> Hello,
> I while ago I asked how to cut a small map from a larger one using the
> region settings as boundary for the small map:
> http://n2.nabble.com/r-mapcalc-changes-color-table-td4072836.html#a4072836
> 
> I tried this again:
> 
> Approach 1: r.mapcalc
> 	
> 	r.mapcalc "cut=if(boundary_raster, large_map,
> null())"
> 
> Approach 2: r.resample
> 
> 	r.resample input=large_map output=cut
> 
> I notice the that using Approach 2, the areas that was outside the set
> region is white. The underlayung rasters are not visible (or only if I
> set the opacity of "cut" to a low value).
> If I use Approach 1 with r.mapcalc, the areas outside the region are
> really NULL() (=transparent) and underlaying larger rasters are visible.
> Only that the result "cut" from r.mapcalc has a new colortable.
> 
> Am I doing something wrong?
> Why is the no such command r.cut?
> 
> Thanks in advance for your help,
> Timmie
> 
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