I am generating filtered Sentinel-1 interferograms for an area with some bright urban targets.
These targets consistently create cross-like artifacts on filtered interferograms.
I assumed it was some co-registration issue on burst corners but I realized they look like backscatter lobes and you can see on this image of intensity (bottom) the artifacts correspond to the bright targets. I then realized it is not on the unfiltered scene (middle).
I use Goldstein filtering with a windowsize of 5, a coherence threshold of 0.2, alpha of 1 and FFTsize of 64. Pretty much default. I have tried smaller window sizes and changing the alpha factor to 0.7 but it still happens. It happens on multiple scenes with different study areas and it does propagate through to phase unwrapping.
I wonder if someone has come across this before and can recommend better filtering parameters or approach to avoid this issue?