Ben, I appreciate this attempt to elucidate the current status of vertical and geocentric coordinate support for OGR/proj.4. Indeed it was work that Frank had been doing the past year or so before being snatched up by the Google. As you've found out, it's not quite complete or thoroughly documented, but the basics are there.
Here's some more information that Frank has produced about the subject: - http://lists.osgeo.org/pipermail/liblas-devel/2010-October/001023.html <-- grid file mechanism for vertical datums - http://trac.osgeo.org/geotiff/wiki/VerticalCS <-- the vertical situation with respect to GeoTIFF One limitation I've run into is there's no easy way to set different vertical and horizontal units for a COMP_CS. This is something I hope can get fixed soon, although I'll admit to being a neophyte when it comes to vertical stuff and how all three things (GeoTIFF, proj.4, GDAL) interact with respect to it. Howard _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
