Frank, Thanks for the reply. I mistakenly said GeoRef when I meant to say GeoTransform. Your description of what would happen if we make the change confirms what we thought.
I think we will go ahead and make the change, and file a ticket. Lots of data are in polar projections, and it seems like a small amount of work now could save a lot of confusion in the future. Best regards, Bruce On Wed, Jan 27, 2010 at 17:44, Frank Warmerdam <[email protected]> wrote: > On Wed, Jan 27, 2010 at 2:22 AM, Bruce Raup <[email protected]> wrote: > >> We propose using terms such as >> >> grid_top_boundary_projected_y >> grid_bottom_boundary_projected_y >> grid_left_boundary_projected_x >> grid_right_boundary_projected_x >> >> Alternatively, grid corner coordinates could be used. >> >> What would the impacts of such a change of names in our files be? If >> the GeoRef field is also in the file, would it break existing software >> for being able to navigate (geolocate) the data? And, would the >> community consider the adoption of more universal terms more generally >> (i.e. in GDAL itself)? > > Bruce, > > I am not really an expert on the GDAL netcdf driver, but > I will attempt to respond. > > First, I think it would be better to just document that the > existing tag names (eg. northernmost_northing) should > just be interpreted with the new definitions > (grid_top_boundary_projected_y) rather than trying > to change the actual tag names in order to gain some > possibly clarity in less common situations. > > I have reviewed the GDAL netcdf driver and it seems to > look for two things. First a GeoTransform value (which I > think is only a GDAL convention). If that is not found it > looks for northernmost_northing, etc. I presume these are > part of the CF conventions, though I don't know for sure. > > I do no see any reference to a "GeoRef" tag. > > So if you make the planned change, and if you do not > also provide the GeoTransform then older versions of > GDAL would not be able to read the georeferencing of > the files. I presume this might also be the case of > almost all other software, even if you did support > GeoTransform. > > However, if you do go ahead with this convention, then > please file ticket with a small sample file so we can add > support for it. > > Best regards, > -- > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, [email protected] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Programmer for Rent > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Bruce Raup http://cires.colorado.edu/~braup/ _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
