Hi everyone,
I have one question: why do I get different displacement results (pls see picture 1 and 2) using the same dataset? All my processing steps and paraemeter values are the same.
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unwrapping errors?
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I’m unsure.Is there anyway to check unwrapping error?
The incorrectly unwrapped areas probably have values that are 2pi (~2.8cm for Sentinel I think) different from the values of the nearby correctly unwrapped pixels. Or 4pi, 6pi etc.
Unwrapping errors are more likely in low-coherence areas.
If you’re making just one interferogram some options are:
a) Try changing the parameters of the unwrapping algorithm, re-run unwrapping and hope it unwrapps correctly .
b) Mask out the areas with unwrapping errors, if those places aren’t important to you.
c) Manually fix the unwrapping errors.
For a and b suggestion, I still get inconsitent results. for C suggestion, how to fix the unwrapping errors by manually?
For c) you would open the unwrapped interferogram in ArcGIS or ENVI etc. and manually draw polygons around the incorrectly unwrapped areas, then add or subtract multiples of 2pi to those parts of the image until they are correct.
But I would recommend a) or b). c) is very time consuming, I don’t think it’s been used much in the last 10 years because most people now do InSAR time series.