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

Michael Barton michael.barton at asu.edu
Mon Oct 2 01:41:05 EDT 2006

Right. I understand, even if I didn't phrase it that way. Does this happen
for any r.mapcalc processing using the same procedures or just ones in which
MASK is the result? Also, is it always an "and" or can you also get the
effects of an "or"? Definitely a 'gotcha' to watch out for. I'm concerned
especially because we are doing a lot of iterative r.mapcalc processing in
scripts and this could be a problem.

Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

> From: Hamish <hamish_nospam at yahoo.com>
> Date: Mon, 2 Oct 2006 17:18:18 +1300
> To: Michael Barton <michael.barton at asu.edu>
> Cc: grass list <grassuser at grass.itc.it>
> Subject: raster MASKs; was [GRASS-dev] interferring ovewrite flags
> 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

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