Hello ticket 70 proposes changing example 5.10 to illustrate the extended syntax proposed
I would suggest that the suggestion to alter the name sin this example is appended to this ticket, to avoid one ticket's amendment overwriting the changes made by another cheers mark -----Original Message----- From: cf-metadata-boun...@cgd.ucar.edu on behalf of Etienne Tourigny Sent: Thu 15/03/2012 02:31 To: John Caron Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] Example 5.10. British National Grid has wrong parameter names John, according to [1] and [2] the names can be used inter-changeably - longitude of the origin (central meridian) - the scale factor at the origin (on the central meridian), specifically: "Scale factor at natural origin" (EPSG and GeoTiff) "Longitude of natural origin" (EPSG, GeoTiff) vs. "central_meridian" (OGC WKT) So I think the CF names should not change and example should be updated to reflect the projection parameters. I have used the correct parameters in the same example in ticket #80 - "Add missing CF parameters to translate Coordinate Reference System properties to/from OGC Well-Known Text format". [1] http://www.remotesensing.org/geotiff/proj_list/transverse_mercator.html [2] https://cf-pcmdi.llnl.gov/trac/wiki/Cf2CrsWkt Regards, Etienne On Wed, Mar 14, 2012 at 8:57 PM, John Caron <ca...@unidata.ucar.edu> wrote: > Example 5.10. British National Grid > > int crs ; > crs:grid_mapping_name = "transverse_mercator"; > crs:semi_major_axis = 6377563.396 ; > crs:semi_minor_axis = 6356256.910 ; > crs:inverse_flattening = 299.3249646 ; > crs:latitude_of_projection_origin = 49.0 ; > crs:longitude_of_projection_origin = -2.0 ; > crs:false_easting = 400000.0 ; > crs:false_northing = -100000.0 ; > crs:scale_factor_at_projection_origin = 0.9996012717 ; > > > but Appendix F has: > > Transverse Mercator > grid_mapping_name = transverse_mercator > > Map parameters: > scale_factor_at_central_meridian > longitude_of_central_meridian > latitude_of_projection_origin > false_easting > false_northing > > I think we can presume that > > scale_factor_at_central_meridian == scale_factor_at_projection_origin > longitude_of_central_meridian == longitude_of_projection_origin > > central_meridian is probably clearer; so maybe just update the example ?? > > or we can add this amendment to ticket #75= "fix documentation and > definitions of 3 grid mapping definitions" > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
