Hi, I am using the Estimate Coherence operator and I am running in to a strange problem. I only use the subtract flat earth phase option (not Topographic phase) and I end up with an image which is cropped based on DEM no data values. I have used the SRTM 3Sec for coregistration and it does not cover the coastal area well. However after the coregistration the values are still there, after the coherence estimation they are masked out. I tried even without the flat Earth phase subtraction but I get the same result. Anyone knows how I could prevent this?
Did you try up SRTM 1sec in case it covers the AOI, if yes, please give a trial and uncheck both SubtractFlatEearthPhase and also SubtractTopographicPhase, and check up the results.
Thank you for your response. As I mentioned I have tried without flat earth subtraction and topographic phase subtraction. Even with all options deselected I get the same result. The DEM should not play role in this operator no?
I meant the SRTM 1sec in corr. step…
I will try that, but I don’t understand why should the DEM used coregistration (with specifically deselected option to mask out areas with no elevation). Maybe a bug that should be fixed?
This might be came back to the difference of both resolution of DEM and Sentinel -1 !
but concerning the reference phases, when they could be subtracted,
to check if it is a bug, you can also run the “interferogram formation” module which also outputs the coherence (allows to select flat earth and topographic phase). Maybe its output is different.
In the end, indeed using different DEM solved the issue. Thanks for the help.