A Novel Mathematical Framework for Multibaseline InSAR Phase Unwrapping.

Multibaseline (MB) interferometric synthetic aperture radar (InSAR) is an extension of conventional InSAR and is used to improve phase unwrapping (PU) accuracy without obeying the Itoh condition. The Chinese remainder theorem (CRT) is the mathematical foundation of most MB PU algorithms for determining the connection between different MB interferograms. However, CRT only exploits the relationship between the interferometric phase and terrain height or surface deformation alone, i.e., the phases of topography and deformation are considered the measurement biases for each other in the traditional processing chains. In other words, traditional MB InSAR cannot directly obtain InSAR products from interferograms that contain both the topography and deformation phases without external information or assumptions. To solve this issue, different from CRT, this article presents a new mathematical framework for MB PU, which provides a likelihood function to jointly estimate the topography and deformation velocity gradient. Based on this framework, a novel MB PU method is proposed for simultaneously obtaining a digital elevation model (DEM) and deformation information from interferograms. The experimental results show that the proposed method is effective and efficient for DEM reconstruction and deformation monitoring.