JPPL: A joint-polarization phase linking algorithm for phase optimization of TSPolInSAR data

Abstract

• As a new polarimetric optimization, the joint-polarization phase linking (JPPL) is proposed to improve the phase quality. • The used joint diagonalization can extract the ESM phases from multi-polarimetric time-series coherence matrices. • Simulated experiment analyzes the interferometric phase quality of the HH, ESPO, and JPPL algorithms quantitatively. • Real experiment demonstrates that the proposed method reduces the speckle noise and restores the interferometric phase. In the time-series interferometric SAR (TSInSAR) technology, the phase linking (PL) algorithm can exploit all interferometric combinations to reconstruct the equivalent single master (ESM) interferograms for the phase quality improvement. According to the Cramer-Rao lower bound (CRLB) for PL, besides the number of spatial samples, the time-series coherence magnitude matrix determines the reconstruction performance of the ESM phases. With the abundance of time-series polarimetric SAR data, many polarimetric optimization algorithms for distributed scatterer (DS) have been introduced, mainly the averaged coherence magnitude maximization-based exhaustive search polarimetric optimization (ESPO) algorithm. However, traditional polarimetric optimization algorithms cannot work satisfactorily because of the unstable statistical characteristics. Similarly, the multi-temporal observations of each polarimetric channel contain interferometric information. From the perspective of redundant observation, introducing full-polarization information can increase the number of observations significantly. Therefore, based on the PL theory and the polarimetric optimization, this paper proposes to perform the joint diagonalization method to simultaneously extract the ESM interferometric phases of interest from three time-series coherence matrices in the Pauli basis polarizations, called the joint-polarization phase linking (JPPL) algorithm. In the experiments, the proposed JPPL algorithm can better improve the optimization performance of time-series interferometric phases of DSs than the HH and traditional ESPO algorithms in terms of speckle noise reduction and interferometric phase restoration.