NOTE: The galeon mailing list is no longer active. The list archives are made available for historical reasons.
Hi John, Thank you for taking the time to write this email. Your points are very clear, and they are very helpful. I must tell you that you give me information and that you sure taught me about CF-1 convention community . I will keep your email as a reference when coding the GDAL NetCDF driver. I have decided to use WKT to encode projections and if I see a new governance structure from CF checked in, I will update the driver. As well, I think for this time being I will relax the lat,lon array requirements. If needed by the community, it would be very easy to compute, but I do not want the driver to be expensive in CPU and space. Thanks again, Regards, Denis 2006/4/26, John Caron <caron@xxxxxxxxxxxxxxxx>:
Hi Denis: 1) CF has unfortunately not yet dealt with datum and spheroid encoding (not sure what "authority" is), but its on our list to tackle. CF does specify a list of known projections and how to encode those (Appendix F). 2) You can, of course, add any metadata you want, eg GeoTransform values, from the CF POV, which CF readers are likely to ignore. 3) Frank Warmerdam and I talked a while ago about using WKT to encode projection info. At the moment, it seems as good as any, with the proviso that the CF group may decide to do it another way (when we eventually decide). 4) Calculating the lat,lon arrays for projections is currently required under CF. I have proposed that this requirement be relaxed, perhaps as a CF profile, for the case where this is unneeded and burdonsome. Issues like this are awaiting a new CF governence structure. 5) Unidata's software maps OPeNDAP datasets into the NetCDF data model (aka "Common Data Model"), so we strongly encourage everyone to use the NetCDF metadata conventions such as CF in their OPeNDAP Servers. We think of OPeNDAP datasets as remote NetCDF datasets, and make access to them as transparent as possible. 6) BTW, CF is an organization independent of Unidata. It grew out of "climate and forecasting" modelers using NetCDF files, but is now broader than that, and is an exemplar "community of practice" around scientific metadata. I am cc'ing to the CF list in case anyone there wants to add more, and so the list can hear about what you are trying to do. In case anyone doenst know, GDAL is an excellent C library for geospatial work, kind of a "Comm on Data Model" for C .
galeon archives: