[gdal-dev] NetCDF grid mapping read issue

[Etienne Tourigny]

On Wed, May 22, 2013 at 2:10 PM, Andreas Oxenstierna <ao at t-kartor.se> wrote:

> Dear list,
>
> GRID cannot interpret (tested with 1.9 and 1.10) the coordinate systems in
> two different NetCDF files storing oceanographic/meteorological data.
> But it can interpret the coordinates in a third NetCDF file.
> PANOPLY, as available from http://www.giss.nasa.gov/**tools/panoply/<http://www.giss.nasa.gov/tools/panoply/>,
> can correctly display all files in lat-lon (4326).
>
> NetCDF file where GDAL can interpret the coordinates:
> https://dl.dropboxusercontent.**com/u/13880880/metoffice_**
> foam1_orca025_GLO_ASLV_**b20120923_dm20120921.nc<https://dl.dropboxusercontent.com/u/13880880/metoffice_foam1_orca025_GLO_ASLV_b20120923_dm20120921.nc>  (CF convention is 1.0)
>
> NetCDF files where GDAL cannot interpret the coordinates:
> https://dl.dropboxusercontent.**com/u/13880880/metoffice_**
> foam1_orca025_NTV_ASLV_**b20110921_dm20110921.nc<https://dl.dropboxusercontent.com/u/13880880/metoffice_foam1_orca025_NTV_ASLV_b20110921_dm20110921.nc>  (CF convention is 1.0)
> http://thredds.met.no/thredds/**fileServer/metno/proff4km/**
> default/files/proffDefault4km_**2013-04-25_00.nc<http://thredds.met.no/thredds/fileServer/metno/proff4km/default/files/proffDefault4km_2013-04-25_00.nc>(be warned: 1.2 Gb)    (CF convention is 1.4)
>
> We have got this information from the Norwegian experts:
> For PROFF data, the rotated lat/lon coordinates are defined so that each
> latitude and each longitude (and therefore each data point) correspond to
> elements in the rlat/rlon vectors.
>

rotated pole is not supported, sorry.

If the driver supported the netcdf-cf coordinates attribute (see Netcdf CF
1.6 section 5.2) these 2 problems would be solved...

There is a mention of this in the netcdf improvement wiki at
http://trac.osgeo.org/gdal/wiki/NetCDF_Improvements

Please add this information to the following ticket
http://trac.osgeo.org/gdal/ticket/4285

regards,
Etienne



>
> The GeoTransform array mentioned in http://www.gdal.org/frmt_**netcdf.html<http://www.gdal.org/frmt_netcdf.html>seems not to be used for these two files.
>
> --
> Best Regards
>
> Andreas Oxenstierna
> T-Kartan Produkt AB
> mobile: +46 733 206831
> mailto: ao at t-kartor.se
> http://www.t-kartor.com
>
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