[GRASS-user] raster MASKs; was [GRASS-dev] interferring ovewrite flags

Hamish hamish_nospam at yahoo.com
Mon Oct 2 00:18:18 EDT 2006

Michael Barton wrote:
> How can you make a mask additive with r.mapcalc? This could be useful
> sometime.

"additive" in a processing sense, not mathematical. (still 0|NULL,1)

for example:  (spearfish)

r.mapcalc MASK='if(isnull(roads))'
r.mapcalc MASK=fields
d.rast elevation.dem

shows elevation where there is fields but no roads, as fields is read
in with a mask in place.


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