[GRASS-user] How To use a raster MASK correctly?

[Roger André]

Hi All,

I would like to use an elevation mask to reclass certain areas in a
raster, while leaving the values outside the mask alone.  Below are my
attempts so far.  Unfortunately, when I export output raster, the
reclass appears to have been applied to entire raster.  Is there a way
to do this using a MASK, or using r.mapcalc to create a new map3 that
modifies specific areas in map2 based on values in map1?

Hope this makes sense,

Roger
-- 

Attempt 1
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  731  r.mapcalc "MASK=if(europe_dem < 100)"
  738  r.info europe_hillshade
  739  r.rescale europe_hillshade from=0,254 to=180,180
out=europe_hillshade_clean