I have a 150km x 150km raster layer of elevation. I'm running a cell-by-cell PyGRASS script, with one step that considers all neighboring cells within a fairly large circular radius (25km). To account for edge effects, I've sub-divided my large region into four 50x50km raster tiles - each created with a raster MASK - factoring out the outer most 25km in each cardinal direction.

I'm trying to figure out a way to include pixels outside of these MASKs created in GRASS GIS. Basically, I'd like to use the MASK as a processing extent, but I don't want to nullify the values in the factored out 25km. They should be included in each neighborhood calculation for cells along the inner border of my mask.

I have quite a number of these 150x150 raster tiles, so I haven't just run my script across the entire region simply to save computational time. Any ideas as to how I can run my script on a subset of this larger raster, without losing values outside the MASKed region?

1 Answer 1


I know it is (too?) late, but I have the same problem and 'partially' resolve with v.buffer with certain distance, and then r.mask over the layer buffer.

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