Le mardi 27 octobre 2015 16:54:56, Kyle Shannon a écrit : > Simon, > > On Mon, Oct 26, 2015 at 5:04 PM, Simon Lyngby Kokkendorff > > <[email protected]> wrote: > > Hello list, > > > > Just observed a puzzling behaviour of the netCDF driver. When creating > > a > > > > netCDF dataset of Byte type, the netCDF driver seems to interpret the > > nodata value as a signed byte. > > > > For example a nodata value assigned with -a_nodata 200, will become -56. > > Of > > > > course one can work around this by simply casting the nodata value (as > > e.g. returned by band.GetNoDataValue()) to an unsigned byte. > > It appears the driver has a sort of data type mis-match with no data > and the band type. A work around, if available, is to set FORMAT=NC4 > as a creation option. I am not sure if it is in gdal or the netcdf > library at this point.
My understanding is netCDF 3 only supports signed byte and GDAL uses a special metadata item _Unsigned=True to correct the interpretation. But it failed to use it to interpret correctly the nodata value. Should be fixed by https://trac.osgeo.org/gdal/ticket/6175 (happy to have feedback from anyone more knowleagable) -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
