Local weight selection for two-dimensional phase unwrapping

Local weights in phase unwrapping play an important role in guiding the flow of the phase integration. Unwrapping algorithms can proceed in a path-following or a non-path-following fashion. In path-following phase unwrapping algorithms, local weights guide the selection of unwrapping paths. In nonpath-following algorithms, the introduction of predetermined local weights is necessary to accommodate phase inconsistencies in practice. In current unwrapping algorithms, these local weights are extracted either from the quality information (correlation in interferometric synthetic aperture radar and modulation in phase shifting interferometry) or from the information contained in the wrapped phase difference alone. In other words, the crucial issue is how a phase unwrapping algorithm should select these location-associated weights in order to prevent the propagation of phase errors. This paper presents a quantitative scheme for selecting local weights for phase unwrapping opt the basis of both these types of information (the quality map and the wrapped phase). Real objects as well as synthetic ones have been investigated for various unwrapping methods in experiments. Integrated 3D free-form object models demonstrate the validity of the phasor-weighted phase unwrapping approach.