aborruso wrote > I have changed only the file format, and I obtain different results. > > Is this normal?
It is "normal", because more than the format has been changed. Compare the CRS definitions in png vs. tif and you'll find and additional extension definition in the tif: EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"] The above "auto-correction" includes the +nadgrids=@null parameter, which in return avoids the "change of ellipsoid" step in the transformation. Hermann -- View this message in context: http://osgeo-org.1560.x6.nabble.com/A-strange-thing-with-a-png-geospatial-file-and-gdalwarp-Is-it-a-bug-tp5075948p5076013.html Sent from the GDAL - Dev mailing list archive at Nabble.com. _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
