Le mercredi 22 octobre 2014 09:02:25, epi a écrit : > Hi, > > I’m tring to read a netcdf file into OSSIM, but unfortunately my file > doesn’t have proper georeferenced metadata, the results of ncdump shows > the following info : > > > int grid_mapping ; > grid_mapping:grid_mapping_name = "polar_stereographic" ; > grid_mapping:long_name = "grid mapping" ; > grid_mapping:scale_factor_at_projection_origin = > 0.933012701892219 ; > grid_mapping:straight_vertical_longitude_from_pole = 58. ; > grid_mapping:standard_parallel = 60. ; > grid_mapping:latitude_of_projection_origin = 90. ; > grid_mapping:false_easting = 2548000. ; > grid_mapping:false_northing = 3988000. ; > grid_mapping:semi_major_axis = 6371000. ; > grid_mapping:semi_minor_axis = 6371000. ; > grid_mapping:earth_radius = 6371000. ; > grid_mapping:ellipsoid = "sphere" ; > grid_mapping:dx = 4000. ; > grid_mapping:proj4string = "+proj=stere +R=6371000.0 +a=6371000 > +b=6371000 +lat_0=90 +lat_ts=60 +lon_0=58 +x_0=3988000 +y_0=2548000" ; > > > Can you help me in creating a proper geotiff file from this netcdf file ? > I tried goal_transform without success on it > > attached at this link [ 1 ] there is the original netcdf > > [ 1 ] http://epinux.com/shared/Mean_2009_2011.nc > <http://epinux.com/shared/Mean_2009_2011.nc>
epifanio, That netcdf file uses a GEOLOCATION array mechanism that requires some processing. I managed to get a rectified geotiff with gdalwarp: gdalwarp -t_srs "+proj=stere +R=6371000.0 +a=6371000 +b=6371000 +lat_0=90 +lat_ts=60 +lon_0=58 +x_0=3988000 +y_0=2548000" NETCDF:"Mean_2009_2011.nc":temperature temperature.tif -overwrite -srcnodata -9725.85 -dstnodata -9725.85 and similarly for other variables in the netCDF. I've determined that the nodata value was -9725.85 by looking at the statistics reported by : gdalinfo NETCDF:"Mean_2009_2011.nc":temperature -stats I *think* (but haven't verified) that in that instance the geolocation must be a regular grid once projected from long/lat to polar stereographic, so probably the netCDF driver could be enhanced to expose a regular geotransform that could save the gdalwarp step. Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
