I am trying to create a DEM using two SLC images (ERS-1/2 tandem). My workflow in as follows.
Apply orbits
coregister
interferogram generation
phase filtering
multillook
snaphu export and then import after phase unwrapping
phase to elevation
At the 5th step, I am not selecting any source bands. My understanding is that SNAP will multilook i, q bands and then it calculates phase from them.
I am also doing it in another way by selecting i, q, coherence as source bands (when multilooking) and then calculating phase using band math option. This way I observe some visual difference in the phase band when compared to above step. Also, when I tried to export the product (obtained using band math option) using Snaphu Export, it is not working. It gives me an error something like “wrapped phase band required”.
So, how phase calculated using band math option is different from phase calculated using multilook operation?
Please take a look once more at these tutorials and the step sequences are followed in, So what is the step before ML?, and what is the step after?, or ML was mentioned as an individual case.
To create a ML is totally correct in the sequence of InSAR, but not using SNAP, I’m talking using GAMMA software to get the average and then corregister the images.
No, there in GAMMA the sequence processing a bit different to what we use in SNAP, That is why I don’t see any necessity of applying ML in InSAR Processing’s sequence using SNAP.
Thanks for the information @falahfakhri
I have unwrapped the filtered interferogram without ML. After importing to SNAP, my unwrapped phase does not seem to be correct. What might be the problem in this case?