r.in.gdal imports GDAL GDT_Float64 (64 bit floating point) as GRASS FCELL (32 bit floating point). This leads to surprisingly large differences between an original DCELL raster map and the re-import of that map:
# nc_spm_08 dataset g.region -p rast=elev_state_500m@PERMANENT res=100 r.resamp.interp input=elev_state_500m@PERMANENT output=elev_state_100m method=bicubic r.out.gdal in=elev_state_100m out=elev_state_100m.tif -c r.in.gdal in=elev_state_100m.tif out=elev_state_100m.import r.mapcalc "diff = elev_state_100m - elev_state_100m.import" r.info -r diff The range of the differences between the original and the re-import is min=-6.10348170084762e-05 max=6.10349170528934e-05 which is magnitudes larger than the 32 bit floating point precision limit. I changed r.in.gdal in r55625 such that GDAL GDT_Float64 is now imported as GRASS DCELL (64 bit floating point). The original and the re-import are now identical. Should this change be backported to GRASS 6? Markus M _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
