On vendredi 25 janvier 2019 11:59:55 CET Sean Gillies wrote: > Hi Even, > > What will the impact be on spatial referencing stored in new datasets? For > example, will users with GDAL 2.5 run gdal_translate and write WKT2 into a > GeoTIFF, thereby creating data that can't be opened using GDAL 2.4? >
Hi Sean, re-adding the list, as it is of general interest. GeoTIFF doesn't use WKT internally ([1]), so this will have no impact, and datasets should be interoperable between GDAL < or >= 2.5. More generally, after exchanges with a few people, I've decided not to change the global behaviour of the exportToWKT() method: it will still export WKT1 for now. So the formats that currently rely on WKT to store their SRS (including GDAL and OGR .vrt, .aux.xml side car) will be little impacted ([2]). In a few years when GDAL >= 2.5 is more widespread, we might reconsider this choice. I've reflected those changes in: https://trac.osgeo.org/gdal/wiki/rfc73_proj6_wkt2_srsbarn? action=diff&version=5&old_version=4 Command line utilities gdalinfo, ogrinfo and gdalsrsinfo will report WKT2 by default however as a hint that things have changed. gdalinfo and ogrinfo will gain a "-wkt_format wkt1" switch to fallback to current behaviour. gdalsrsinfo has already a switch to select the WKT variant), as this should have less impact. Even [1] Except as an extension of a few SRS that can't be encoded with GeoTIFF keys. In that case, GDAL uses a ESRI specific trick that consists in exporting the SRS as a ESRI WKT1 string. That behaviour will be unchanged. [2] I write "little" and not "not" on purpose since the WKT1 export will not be strictly identical to previous versions. In particular AXIS, compliant with the ordering of the defining authority, will be output -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
