Estimation of Terrain Elevation by Multi-Frequency Interferometric Wide Band SAR data

摘要

Purpose of the present paper is to investigate the possibility to reconstruct strongly discontinuous terrain height profiles, starting from more than one wrapped interferometric phase signals obtained at different working frequencies. In absence of phase noise, the use of two frequencies that are in irrational ratio allows to have a unique solution. The presence of the decorrelation noise, however, makes such methods not applicable in practical cases. We propose an unwrapping method based on a Maximum Likelihood estimation technique and using frequency diversity. Since it does not exploit the phase gradient, it assures the uniqueness of the solution, also in the case of piece-wise continuous elevation patterns with strong discontinuities. This result is derived from the consideration that the likelihood function obtained combining frequency diversity information exhibits a unique global maximum.