Hi, I’m working with Sentinel-1 image (GRD) and I’ve applied standard process chain through SNAP in order to work better in QGIS, but I don’t know which format is better. I’ve tried GeoTiff but the final image was 8.70 GB! It’s ok?
There is a tutorial in exporting data: Export of products from SNAP
There are other tutorials to find in the tutorial section on the STEP website.
Regarding the size. You might use Big-GeoTiff. This uses compression.
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Working in Windows on a VPN in the time of COVID-19, multi-GB files have a been “problematic” (more accurate terminology not being appropriate on public forums).
The lack of good metadata support in GeoTIFF has also a problem for me (people ask for GeoTIFF’s, then months later ask for metadata while writing up the results). I don’t see support for internally compressed NetCDF4-CF in SNAP, but NASA OCSSW software uses internal compression and are much smaller than SNAP’s BEAM DIMAP data using the same resolution and area:
% % ls -l A2006167181000.smi_chlor_a_mn.nc \
A2006167181000.smi_chlor_a_mn*.tif \
A2006167181000.smi_chlor_a_mn.data/chlor_a.img
-rw-r-----+ 1 X 2359296 May 29 2020 A2006167181000.smi_chlor_a_mn.data/chlor_a.img
-rw-r-----+ 1 X 508119 Oct 22 2017 A2006167181000.smi_chlor_a_mn.nc
-rw-r--r-- 1 X 703507 Nov 6 2020 A2006167181000.smi_chlor_a_mn.tif
-rw-r-----+ 1 X 703511 May 14 13:16 A2006167181000.smi_chlor_a_mn_bigv8.tif
Third party tools such as CDO (runs under Cygwin64 in Windows) and nccopy can be used to apply internal compression. Support for internally compressed NetCDF4 in other tools is spotty. With modern hardware, the time penalties for compression are small compared to time penalties for transferring large files over networks. I hope
SNAP will support internal compression when writing NetCDF4 files “real soon now”.
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NetCDF4 is already supported. Since years. Actually it was already possible to use it in BEAM.
NASA NetCDF4 files with internal zip compression have worked using the NASA jars since they arrived, but third party files don’t (and are not being made public due to the lack of support in Matlab and ArcGIS). The original SZ (szip library) compression used proprietary software, but the HDFGroup arranged a free license for HDF5 (as used by NetCDF4) for all but people using szip to develop commercial products that write compressed NetCDF4. This meant that linux distros, Cygwin, and Anaconda did not support SZ internal compression. Meanwhile libfec was developed as a “drop-in” replacement for szip, and is now used by Debian and Fedora.