Hi Julien,
If you want to put up your code on github, I can volunteer to help port it
to 2.x. Generating unittests would not be a problem. Will probably take
existing datasets in the test suite and add a group around the datasets to
begin with.
Not very familiar with MODIS/VIIRS but looks like its nc4 with groups but all
the dimensions are datasets under root. Maybe we can generalize this too?
Piyush
From: Julien Demaria <[email protected]>
Date: Saturday, October 13, 2018 at 4:09 PM
To: "Agram, Piyush S (334D)" <[email protected]>,
"[email protected]" <[email protected]>
Subject: RE: parsing of netcdf4 no-data values in hdf5 reader
Hi,
I have already already implemented NetCDF4 groups support for GDAL in 2015 and
use it to read for example NASA OceanColor MODIS/VIIRS L2 products, see the
attached email.
Unfortunately I never found enough time to add corresponding GDAL autotests
(covering all my modifications) to be able to provide these improvements to the
GDAL community.
The other problem is that I implemented this in GDAL 1.11 so porting to latest
GDAL need some work, I started to do that in 2016 but never finished...
But I think my code is good and it will be a pity if not reused...
I think I can try to finish the porting to the latest GDAL and provide it to
GitHub, but I'm still not sure to have enough time to implement all needed
corresponding GDAL autotests. If you want to contribute you are welcome! ;-)
Best Regards,
Julien
-----Message d'origine-----
De : gdal-dev [mailto:[email protected]] De la part de Agram,
Piyush S (334D)
Envoyé : samedi 13 octobre 2018 21:00
À : [email protected]
Objet : Re: [gdal-dev] parsing of netcdf4 no-data values in hdf5 reader
Hi Even,
Looking into the issue, I think the NETCDF reader does not read datasets
located insides groups for Rasters. There are 2 specific parts of the reader
that seems to be the issue:
1. If the drivers does not find 2 arrays that are dimensions under root it
bails. This would need to be updated if data is organized within groups and
there are no dims/vars at the root level.
2. It only looks into the groups when used for reading vectors and when it does
it only parses the string types for geometry definitions. This would need to be
updated.
Some related questions to see if anybody is already planning to contribute
these capabilities:
1. Update to NETCDF raster driver to look into sub-groups as well? The spec
does not seem to talk about this. Assuming they are trying to be backward
compatible with formats that did not support groups - is this acceptable?
2. Support for CF conventions in HDF5 reader? NASA/ESRI seem to be happy
working with CF-compliant HDF5.
Adding either support will let people use GDAL with xarray etc.
Piyush
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
