Robust algorithms for phase unwrapping in SAR interferometry

The paper addresses the problem of the development of robust algorithms for unwrapping the interferometric phase (IF) produced in the SAR interferometry. Two practicable methods are proposed based on tile Green's first identity with properly chosen Green's functions satisfying the imposed Newmann's boundary conditions. These Green's functions are being found when solving the Newmann's problem by means of the potential theory or through the representation of the Green's function as an infinite two-dimensional series in the eigenfunctions of the Helmholtz equation. Then, the algorithms are being further elaborated using the method of regularization while searching for a gradient of the measured IF. Thus, the proposed approaches take into account die presence of tile measurement noise in the IF. Tile developed algorithms proved to be stable both with respect to propagation of errors and with respect to local perturbations in the unwrapped phase due to inaccuracy of-the measurement of a wrapped IF. The proposed algorithms allow their efficient numerical implementation using the fast Fourier transform. Experiments on data acquired by tile satellite ERS-1 and supplied by CNES show high performance of both developed methods.