Hi again,
as you may already knows from other topics I have created on the forum, I’m working on reprojecting some OLCI L1/L2 and SLSTR L1/L2 products.
Now I have a question about masks and quality flags usage.
So I have a Graph chain defined like this:
- Read the xfdumanifest
- Subset (with bandnames and region parameters)
- Reproject
- #N Subsets (1 band each)
- #N Writes (1 band each to tiff )
I have seen around on the forum some samples about bandMaths OP usage to export masks as bands.
So I was able to create a standalone graph which simply read a product and export the mask as a target band using the name of the mask as expression.
Couple of questions now:
- Will the reproject/subset(Region) operations also be applied to masks OR there is any way to make this happen with some additional nodes/configuration params?
- Supposing I would like to create an output tif with pixels covered by clouds being filtered out, should I define a BandMaths node between previous steps 4 and 5 applying a kind of AND with the quality_flags?
- What about if I want generate on steps 4 and 5 a quality_flags output GeoTIFF? will the quality_flags mask survive and be propagated and properly reprojected after steps 1,2,3?
- Final question: I see some netcdfs from OLCI L2 containing quality flags as “long” datatype whilst the bandMaths op supports up to Int32. Opening them on SNAP Desktop GUI I see WQSF_lsb and WQSF_msb so I think it’s splitting it into 2 representable datatypes. In relation to previous 3 questions, how should I deal with that on GPT graph?
Thanks for your assistance and sorry for all of these questions.
Cheers,
Daniele