[GRASS-user] r.mask: no MASK created when using many categories

[Mira Kattwinkel]

Dear List,

I am using r.mask to create a new raster map that only contains certain 
categories given in 'maskcats'. Then, I use r.mapcalc to save the map 
under a new name and (to be on the save side) delete the MASK with 
r.mask flag '-r'. I do this in a loop and it works fine until a case 
when the number of categories to combine is 213 (trail and error lead to 
106 as the maximum number that works fine). Flag 'verbose' gives the 
message that a MASK was created, but none is there. The problem arises 
in both cases when I directly use Grass or through R using execGrass.

Is there a limit in the number of categories that can be passed to 
r.mask? I did not find any hint about that. Additionally, I wonder why 
there is no error message but in the contrary one that tells me that a 
MASK was created even when it failed.

In case the details are important (or if anybody has a better idea how 
to achieve what I want): I have a raster map of subcatchemts belonging 
to stream segments created with r.stream.basins. For the endpoints of 
segments, I want to combine these subcatchments to a total catchment 
raster map containing all upstream catchments.

Thanks a lot,

Mira


-- 
Dr. Mira Kattwinkel
Quantitative Landscape Ecology
Institute for Environmental Sciences
University of Koblenz-Landau
Fortstraße 7
76829 Landau
Germany
Phone: + 49 6341 280-31553
Office: Building I, Room 2.02