On vendredi 25 octobre 2019 16:02:57 CET Gregory, Matthew wrote: > Hi all, > > I am warping and upsampling an image from 4km to 30m using cubic resampling. > I've been warping different sized windows from the source image like this: > > # Larger window > gdalwarp > -t_srs EPSG:5070 > -te -2303985 2406015 -2033985 2649015 > -tr 30 30 > -of GTiff > -r cubic > in.vrt > out.tif > > # Single line of above window > gdalwarp > -t_srs EPSG:5070 > -te -2303985 2648985 -2033985 2649015 > -tr 30 30 > -of GTiff > -r cubic > in.vrt > line.tif > > Naively, my expectation was that the overlap region would have identical > values, but they don't. I assume this means that the source (4km) pixels > are being subset down to a smaller window before warping in the latter case > that don't necessarily include the same 16 nearest pixels as in the first > case? I had a brief look through the Warp API tutorial and it looks like > it may have something to do with the GDALSuggestedWarpOutput, but I didn't > dig too deeply there.
maybe try to add -et 0 and/or -wo XSCALE=133.33333333333334 -wo YSCALE=133.33333333333334 where 133.3333 = 4000 / 30 XSCALE/YSCALE are "un-documented" there: https://github.com/OSGeo/gdal/blob/master/gdal/alg/gdalwarpkernel.cpp#L1120 -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
