We have a GPT script which is processing “S1B_IW_GRDH_1SDV_*” files and writing to NetCDF4-CF. The .nc files produced can be read into other software packages compatible with NetCDF.
However, when we add a “Subset” step to GPT just before the “Write” step, the NetCDF produced is no longer a valid NetCDF and cannot be opened, neither in SNAP nor in other NetCDF readers. SNAP gives the error “No appropriate product reader found. File XX can not be opened.”
We are subsetting using Geographic Coordinates and a rectangle defined using:
POLYGON ((-111.436 56.725, -111.4 56.725, -111.4 56.713, -111.436 56.713, -111.436 56.725))
The Subset step appears to be working. When we save to a different file format (BEAM-DIMAP), it can be opened by SNAP without any issues.
How can we subset our dataset and also produce a valid NetCDF file?
Update: I also tried using NetCDF4-BEAM. The NetCDF can be read into a NetCDF visualization software, and I can view the band information. However, the lat lon coordinates don’t appear to have been subset (they have the original lat/lon), and the dimensions of the band are called y1 and x1 instead of lat lon or x y…
Update 2: I should also mention that we’ve previously used Sentinel-3A products which were subset and exported to NetCDF4-BEAM (using snappy rather than GPT) and had no issues, so it seems to be either a Sentinel-1 or GPT-related issue.