[gdal-dev] Creating NetCDF dataset with sub datasets

[Pierre Chatelier]

Ok, I can confirm that
-creating a dataset with <n> bands with the netCDF driver works
-saving the dataset will write the expected "SUBDATASETS" domain with 
"SUBDATASET_<i>_NAME=NETCDF:"<file>":"<band name>"

But I can't figure out how to customize the <band name>, which is Band1, 
Band2, Band3...
I tried GDALRasterBand::SetDescription(), but without success

Also, is there a reason why AddBand() is not supported by the netCDF 
driver ? I expected it to be able to add bands on demand as new "netcdf 
variables".

Pierre

> Hi,
>
> If your input dataset has multiple bands, each band will be written as 
> a separate netCDF variable, and thus read as multiple subdatasets. The 
> constraint is that as your input is a single raster, all bands must 
> share the same georeferencing.
>
> If you want to write multiple independent variables, then you'll have 
> to use the GDAL multidimensional API. Cf 
> https://github.com/OSGeo/gdal/blob/master/autotest/gdrivers/netcdf_multidim.py 
> . h5py is also quite convenient
>
> Even
>
> Le 07/03/2024 à 09:47, Pierre Chatelier via gdal-dev a écrit :
>> Hello,
>>
>> I just had my first encounter with a NetCDF file. GDAL opens that 
>> flawlessly, I can identify the subdatasets and open/read them thanks 
>> to the SUBDATASET_n_NAME, as advertised in 
>> https://gdal.org/drivers/raster/netcdf.html
>>
>> However, I am confused by the ability to create such a file with GDAL.
>> Let's say I have a bunch of images that I want to pack as NetCDF 
>> through GDAL.
>> Should I use bands or groups to let GDAL create the sub datasets ? 
>> Will GDAL create the metadata SUBDATASETS domain for me ?
>>
>> The NetCDF file I am supposed to create should use HDF for sub 
>> datasets. No problem for reading (I have compiled GDAL with the HDF 
>> support and it works, I can open my sample file), but how do I tell 
>> GDAL to *write* that ? Should I create real datasets with the GDAL 
>> HDF driver and then gather them into a single one with GDAL NetCDF 
>> driver ?
>>
>> Can you give some hints about what I am supposed to do ?
>>
>> Pierre
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>