[GRASS-user] Do filters available in GRASS takes care of cell padding?

Helmut Kudrnovsky hellik at web.de
Sat Nov 28 06:32:57 PST 2015

Uttam Sinha wrote
> Hi,
> Do the filters available in GRASS GIS such as average, low pass, high pass
> filters take care of cell padding automatically?
> By Cell paddding, I refer to duplicating the first row on top, duplicating
> bottom row at the bottom, duplicating first column before the actual first
> column and duplicating last column after the actual last column.
> This may be required if we are trying to do any filter operation on the
> (1,1) of the image. The filter will search for pixels above and left of
> the
> center pixels.
> Can we do it using r.mapcalc? Please suggest how to do this?
> Thank you for any response.
> Uttam.

no idea about cell padding, but may be see here how to do r.mapcalc
calculating cells by neighboring cells.


Moving window of 4 cell in every 8 direction and do a boolean comparison.
Boolean value (e.g. the result of a comparison) is an integer, with 1 for
true, 0 for false. Then do a r.mapcalc calculation with the moving window.

best regards
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