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

[Hamish]

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.


Hamish