Enrico Gallo wrote: > I would like to use r.mapcalc in order to compare 2 different resolution > floating-point raster (A = 1km and B = 100 m) and to calculate some > statistics on the finest resolution map ( so g.region res=100) > > As the two layers have different resolution and origin, some doubts arise : > > does r.mapcalc use *nearest neighbour* to perform calculation?
The GRASS libraries use nearest-neighbour to resample raster maps to the current region. This affects any module which doesn't specifically change the region (and r.mapcalc doesn't), [The r.resamp.* modules *do* change the region to match the input.] > is a resample using *r.resamp.interp* (bilinear or cubist) suggested/needed > before running r.mapcalc? That depends upon the nature of the data. Ask yourself: if r.mapcalc insisted that all inputs had the same resolution and alignment, how would you perform resampling? If you would use nearest-neighbour, then you don't need to manually resample, otherwise you do. -- Glynn Clements <[email protected]> _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
