Phase unwrapping for interferometric synthetic aperture radar by use of Helmholtz equation eigenfunctions and the first Green's identity

We develop a new algorithm for interferometric synthetic aperture radar (SA R) phase unwrapping based on the first Green's identity with the Green's fu nction representing a series in the eigenfunctions of the two dimensional H elmholtz homogeneous differential equation. This provides closed-form solut ions with use of one- or two-dimensional fast Fourier transforms. The algor ithm is elaborated by using adaptive regularization of the interferometric phase gradient estimation. To diminish underestimation of the unwrapped pha se typical of the linear phase unwrapping algorithms, the bias in the measu red interferometric SAR phase is calculated in terms of the probability den sity function of the error in the processed interferometric SAR phase. (C) 1999 Optical Society of America [S0740-3232(99)00202-1].