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

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
--------------
  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

Figured it out. Used the following r.mapcalc expression:

r.mapcalc "new_hillshade=if(europe_dem < 100, 180, europe_hillshade)"

I think I might be in love!
--

On Sat, Oct 17, 2009 at 10:27 AM, Roger André <randre@gmail.com> wrote:

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
--------------
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