Phase Unwrapping
Phase can only be detected between -
and ,
but the actual phase shift between two waves is often more than this. Phase unwrapping is the process
of reconstructing the original phase shift from this "wrapped" representation. It consists of adding
or subtracting multiples of 2 in the appropriate places to
make the phase image as smooth as possible. To convert interferometric phase into elevation, you must
perform phase unwrapping.
Phase unwrapping is easy to do in areas of high coherence. Where decorrelation or layover contaminates the phase, it can be very difficult to extract topography accurately.
and ,
but the actual phase shift between two waves is often more than this. Phase unwrapping is the process
of reconstructing the original phase shift from this "wrapped" representation. It consists of adding
or subtracting multiples of 2 in the appropriate places to
make the phase image as smooth as possible. To convert interferometric phase into elevation, you must
perform phase unwrapping.
 )
|
 )
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Phase unwrapping is easy to do in areas of high coherence. Where decorrelation or layover contaminates the phase, it can be very difficult to extract topography accurately.
Often, phase unwrapping algorithms leave "holes", where they cannot determine the actual phase. They produce
errors, where the unwrapped phase is (sometimes extremely) inaccurate.