Two dimensional phase unwrapping based on the Laplace and Eikonal equations

Abstract

In interferometric synthetic aperture radar (IFSAR) applications the goal is represented by the evaluation of the digital elevation model (DEM) of the illuminated area. This result is achieved by exploiting the phase interference of two spatially separated side-views of the same site. In order to correctly generate the interferogram, some operations must be carried out on the received data. Firstly they must be correctly focused, secondly the obtained complex images must be properly registered. These operations result in a phase interferogram which represents the phase values restricted to the range [-/spl pi/,/spl pi/) (wrapped values). Phase unwrapping procedures allow the unwrapped phase values to be obtained which are directly linked to the desired DEM. To solve this problem several techniques have been proposed. The present authors give a new phase unwrapping algorithm which utilised Green's identity and Green's functions. The proposed technique is intrinsically two-dimensional, is robust and quite insensible to the propagation of the errors generated by non exact phase measurements.