[GRASS-dev] r.mask: odd behavior?

Veronica Andreo veroandreo at gmail.com
Sun Nov 19 12:19:45 PST 2017


Hi devs,

I found that r.mask does not behave as I would expect and I would really
appreciate some clarification.

The issue is the following: I apply a mask, then I do some processing, I
remove the mask and when I display the resulting map, all the pixels were
processed. I would expect that those pixels that I masked were treated as
NULL and not considered exactly as the message says:

"All subsequent raster operations will be limited to the MASK area. Removing
or renaming raster map named 'MASK' will restore raster operations to
normal."

Otherwise, what's the point of applying a mask?

This is an example with NC:

g.region raster=landcover_1m -p
r.category landcover_1m
r.mask raster=landcover_1m maskcats="1 thru 6"
d.mon wx0
d.rast landcover_1m
r.mapcalc "applied_mask = 1"
r.mask -r
d.erase
d.rast applied_mask <<-- everything is there, no holes...

The only operation that gave me what I would expect when I apply a mask
was:
r.mapcalc expression="applied_mask=1-MASK"

Can someone, please, test/clarify this?

thanks much in advance!
Vero
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