I am also using the netCDF driver to read weather data from a thredds server. I am curious how the tag names for the metadata were defined in the driver. For example, the CF convention for the central meridian is "longitude_of_central_meridian" and in the netCDF driver it is "central_meridian". This causes the true value to be skipped and set to a default value of 0.0 in my case.
regards, # =================== Kyle Shannon Physical Science Technician RMRS Fire Sciences Lab Fire, Fuels & Smoke - RWU 4405 5775 Highway 10 W. Missoula, MT 59808 (406) 829-6954 [email protected] # =================== On Thu, Jan 28, 2010 at 3:52 PM, Bruce Raup <[email protected]> wrote: > 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<http://pobox.com/%7Ewarmerdam> > > 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/ <http://cires.colorado.edu/%7Ebraup/> > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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