An approach to two-dimensional (2-D) phase unwrapping for synthetic apertur
e radar (SAR) interferometry is presented, based on separate steps of coars
e phase and fine phase estimation. A technique called adaptive multiresolut
ion is introduced for local fringe frequency estimation, in which differenc
e frequencies between resolution levels are estimated and summed such that
a sufficiently conservative phase gradient field is maintained, A coarse un
wrapped phase of the full terrain height is then constructed using weighted
least-squares based on coherence weighting. This coarse phase is used in a
novel approach to slope-adaptive spectral shift filtering and to reduce th
e phase variation of the interferogram. The resulting interferogram can be
more accurately multilooked and unwrapped with any algorithm, In this paper
, fine phase construction is done with weighted least-squares and with weig
hts determined by simple morphological operations on residues. The approach
is verified on a simulated complex interferogram and real SAR data.