Displacement miscalculation


I have generated an interferogram according to the TOPSAR tutorial. The images that I’ve used are these:
I have unwrapped the images using SNAPHU and then calculated the vertical displacement and applied range doppler terrain correction. The problem is that the displacement values at the colour bar don’t agree with the stage data that I have. Furthermore, I notice that there is a displacement value for every pixel in the image, which doesn’t make sense to me. I am working in a small subset that covers an area of 8 km^2.

What could there be wrong? Is there any extra filter that I should apply or any setting that I should change?

I would really appreciate any kind ideas!

the vertical displacement usually is just a relative measure. So you should then level it to your ground by identifying a pixel where you expect no change and subtract this value from your image.

You could also consider to mask out areas with low coherence.

Both was described in this topic:

I haven’t seen this so far, thank you very very much! :slight_smile:

Even if your processing is “perfect” the InSAR-phase still contains the atmospheric contribution on top of the deformation-related signal.