According to the notebook, I see the geotransform and spatial_ref attrs are used for orthorectification. Note that GT[2] and GT[4] are zero in the attrs. So, does that mean we can only use geotransform and spatial_ref for orthorectified data?

Actually, I have tried to use pyresample's AreaDefinition to define the area. The derived lon/lat values are different from these in the location group of NC file. I suppose that's because these attrs from the NetCDF file only works for orthorectified data.

If I'm wrong, please feel free to correct me. I'm curious how to use geotransform and spatial_ref for original data, if that should work ...