Hi,
I am new to using SNAP and SAR imagery.
I have dozens of Sentinel-1 SLC files that I would like to bulk import and do all required pre-processing using SNAP.
The project will look at Polarimetric analysis and I would also like to analyse deformation using interferometry.
I think these two analysis methods might require different processing steps?
Can anyone point me in the right direction to achieve both of these goals using python in SNAP.
Thanks very much
May be training from here can help you.
From my experience the first and most difficult step is to get snappy to install in your python environment. If you work with multiple python environments I suggest you set up one specifically for snap. Unless they release the new SNAP 10 you will have to set up SNAP 9 with an old version of python.
Hi,
This is great. Thank you.
There is plenty of other great resources in there that I will dive into also.
Cheers
Ok. Sounds like a tricky process.
I am week one day one with SNAP but have average python experience so I will research Snappy and see if I can pull this off.
Was hoping it would be a something like a python interface in SNAP and just input code to batch process.
I did read something (not confirmed as genuine) about using the model builder function in SNAP and adding the model builder saved graph file Into a python script.
No idea if this is the best way to do this.
Essentially, I have 40 SLC Sentinel-1 files and I want to use them for multiple analysis (polarimetry, interferometry) so the processeing steps will be slightly different as I understand it.
SLC is best for interferometry? Would the SLC work for Polarimetric analysis or should this be GRD (Sentinel-1)?
There is a graph builder in the SNAP GUI which may fit your needs. You build the graph (or input an XML that describes your graph) for your batch processing.
The way they made snappy was something like an emulator or wrapper for their Java classes so if you’ve never seen java code it looks a little janky in a python setting. I think this will change once they release snap 10? Not sure. Note that snappy is also the name for an existing compression algorithm so that just adds to the confusion.
I recommend you wait for when they release this: GitHub - senbox-org/esa-snappy.
I think the rename to esa-snappy and all the other changes will help move the python version to become more pythonic and more accessible to science people. I believe they said they’ll release it with SNAP 10.
But if you really want to work with python for SNAP 9 here is the most helpful resource I found:
https://senbox.atlassian.net/wiki/spaces/SNAP/pages/50855941/Configure+Python+to+use+the+SNAP-Python+snappy+interface+SNAP+versions+9
As for polarimetry and interferometry, I’m sorry I can’t help. Not familiar with these yet.
For Sentinel-1 only SLC products contain the phase information needed for InSAR or polarimetric analysis.
You can do bulk-processing by calling gpt and your pre-saved SNAP graphs by using shell-script, python etc. The are tutorials on how to get this done.
edit: here’s an example of scripted SNAP processing with Python: GitHub - ESA-PhiLab/OpenSarToolkit: High-level functionality for the inventory, download and pre-processing of Sentinel-1 data in the python language.