Adrien, > opening 2 rasters with different resolutions i noticed a shift. > > Asking our imagery provider, i was told the origin coordinates they > store in image header (JP2 files) are those of the top left pixel center. > > GDAL reads origin coordinates as the top left pixel top left corner > coordinates, as i'm used to. > > > Of course, i fixed my problem, the hacky way, playing with > gdal_translate a_ullr option, but: > > How to deal with this?
Normally, if the image provider did its job correctly, GDAL should report a consistant georeferencing in its convention (top left corner of top left pixel is 0,0), doing half pixel shift if needed. There are 2 ways of encoding georeferencing in JPEG2000: - GMLJP2, which has a convention of center of top left pixel. GDAL adds a half pixel shift to translate into its convention - GeoJP2 (GeoTIFF-in-JPEG2000), which in most cases, uses the pixel-is-area convention, which is the same as GDAL. In rare cases, it could be pixel-is- center, in which case recent versions of GDAL (1.11 perhaps, 2.0 for sure), will translate to GDAL convention. Both can be present in a same file, in which case GDAL will use GeoJP2 contents. So if you're seeing a half pixel shift, either there's a remaining bug in GDAL (not sure where), either the image provider didn't encode it correctly > How not to worry about georeferencing each time i load a raster file? > Is there any OGC recommendation about origin coordinates storage? GMLJP2 mentions it. GMLJP2 v1 wasn't completely clear about that, but the language of GMLJP2 v2 has clarified it. Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
