[GRASS-user] raster analysis: hot to get one <elevation raster> from two elevation rasters?

Nikos Alexandris nikos.alexandris at felis.uni-freiburg.de
Tue May 27 08:14:05 EDT 2008

On Tue, 2008-05-27 at 12:05 +0000, christian Brandt wrote:
> What I want to do is to get just one <elevation-raster> with combined
> elevation data from DGM raster and buildings raster
> Hence I tried the r.mapcalculator as follows:
> r.mapcalculator amap=dgm bmap=geb formula=A+B outfile=dgm_geb

Dear Christian,

r.mapcalc or r.mapcalculator should work.

Just some ideas (which you might have tested already, but anyway... ):

1. check the range of your "dgm" and "geb" data to be sure that both
have "valid" values

r.info -r dgm
r.info -r geb

(or use r.describe to list all values contained in your maps)

2. check the computational extent in you LOCATION:

g.region -p

or why not set directly to match the extent of one of your maps:

g.region rast=dgm


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