Even Rouault <even.rouault <at> mines-paris.org> writes: > > Hi Jukka, > > > I can also see that GDAL does have a config option GMLJP2OVERRIDE but I > > could not easily find what is is doing. > > /* -------------------------------------------------------------------- */ > /* This is a backdoor to let us embed a literal gmljp2 chunk */ > /* supplied by the user as an external file. This is mostly */ > /* for preparing test files with exotic contents. */ > /* -------------------------------------------------------------------- */
Ok, not for mortals. > > > > And finally when I was playing with a "gdal_edit.py" utility I discovered > > that there are at least 4 ways to georeference a JPEG2000 file: > > - use worldfile .wld or .j2w > > - use internal GeoJP2 (GeoTIFF) georeferencing > > - use internal GML georeferencing > > - use an external .aux.xlm file > > > > I noticed that command > > python gdal_edit.py -a_srs epsg:3067 metajp2test.jp2 > > was creating a file names "metajp2test.jp2.aux" which does contain the > > right georeferencing data. > > > However, if I run gdalinfo it is looking for > > the internal GeoJP2 metadata and it reports that my JPEG2000 file is still > > using an unknown projection. > > Was it with the JP2OPENJPEG driver ? JP2KAK and JP2ECW should return what is > found in .aux.xml. Yes, it was JP2OPENJPEG. I was testing in the average user mode and did not bother to search Windows binaries with other JPEG2000 drivers and playing with GDAL_SKIP config option. They are not for mortals either. It would be good if all the JPEG2000 drivers would behave in a similar way with georeferencing. > I also agree with Frank that PAM information should override internal > information. > > In the case of JPEG2000, I think it might be possible, pending some work, to > edit the JP2 boxes to rewrite the GeoJP2 and/or GMLJP2 boxes in place. Well, > maybe not in all cases if the size of the new boxes is larger than the old > boxes. In which case a utility could rewrite a slightly larger file by shifting > the compressed imagery off a few bytes, but without modifying it at all. I am remembering that for the JPEG2000 standard it is OK to write the boxes also after the codestream. I am also remembering that you wrote a script that did that with GML box about one and a half year ago. I bet that some JPEG2000 libraries would not find the boxes at the end of the file, though. -Jukka- _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
