Upendra, Kyle, et al, I proposed the use of an optional wkt attribute, for similar reasons to those that you suggest, when I put together my submission for additional CRS attributes to the CF standard. You can read some of the discussions under CF trac tickets #9 and #18.
This particular attribute received a lukewarm reception at the time. However, if you feel there is a stronger case now then by all means submit another proposal to the CF trac site. Of course, there's nothing to stop you adding a wkt attribute to your netcdf files today. ESRI does just this. So long as the files are CF-compliant in other respects then any additional attributes are supplementary (I'm presuming CF-compliance is your goal). Regards, Phil > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Upendra Dadi > Sent: 03 March 2010 20:42 > To: Kyle Shannon > Cc: [email protected] > Subject: Re: [CF-metadata] equivalent of TOWGS84 in CF > > As I understand, scientists often use reference systems > more complex than can be represented using the WKT. So it > might not be good to fully depend on WKT, but having an > optional attribute which can be used whenever possible might > be a good idea. > > Upendra > > Kyle Shannon wrote: > > I don't believe there are any such tags for TOWGS84. I > would like to > > see a more conformance or integration with OGC WKT as well. This > > could take the form of spatial reference well known text or proj4 > > definitions. For the spheroid in cf, you have to specify > earth_radius > > and inverse_flattening or semi_major_axis and semi_minor_axis. I > > think longitude_of_prime_meridian is in there too. The other > > grid_mapping tags are for projected coordinate systems. > > > > > > > > -Kyle > > > > > > On Wed, Mar 3, 2010 at 12:21 PM, Upendra Dadi > <[email protected] > > <mailto:[email protected]>> wrote: > > > > Hi, > > I am new to CF convention. I am looking at how to incorporate > > coordinate system information in the netcdf file. > Referring to the > > CF documentation, I found that there are parameters like > > grid_mapping_name, semi_major_axis, longitude_of_prime_meridian, > > etc to describe the coordinate system.But I haven't found any > > attributes for specifying Bursa Wolf transformation parameters > > (equivalent of TOWGS84 in WKT). Or am I missing something? These > > parameters may be required when I am using data which > is not based > > on WGS 84 datum in order to be able to apply proper > > transformation. Thanks. > > > > Upendra > > > > > > > > > > > > > > _______________________________________________ > > CF-metadata mailing list > > [email protected] <mailto:[email protected]> > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > > > > ---------------------------------------------------------------------- > > -- > > > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
