[gdal-dev] NetCDF driver getting wrong values if compared to HDF5
Even Rouault
even.rouault at spatialys.com
Wed Jul 31 08:19:29 PDT 2019
On mardi 30 juillet 2019 21:48:45 CEST Ivan Lucena wrote:
> Unsupported netCDF datatype (7), treat as Float32.
Given that
#define NC_UBYTE 7 /**< unsigned 1 byte int */
and
https://github.com/OSGeo/gdal/blob/master/gdal/frmts/netcdf/netcdfdataset.cpp#L357
it seems you would have a GDAL build against a netCDF build without NC4 support.
That said, even with that, I would have expected the ubyte to float32 conversion to be lossless.
but according to
https://www.unidata.ucar.edu/software/netcdf/docs/group__variables.html#ga0ab808702d73b7f52be14b1e54473902
"""
The nc_get_vara() function will read a variable of any type, including user defined type.
For this function, the type of the data in memory must match the type of the variable - no data conversion is done.
"""
So you could get pretty much garbage.
Solution: build GDAL against a netCDF build that has NC4 support
Even
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