Correlation Analysis on Interferometric Coherence Degree and Probability of Residue Occurrence in Interferogram

The interferometric coherence degree is a very important indicator of the quality of interferometric phase values in interferogram; while the existence of residues is a stubborn problem for phase unwrapping. Both of them are the vital factors influencing the performance of phase unwrapping algorithms in interferometric synthetic aperture radar (SAR) processing. In general, residues tend to be located in the regions with low coherence degree, which is just a qualitative description for the relationship between interferometric coherence degree and probability of residue occurrence. In order to further reveal the quantitative relationship between them, we actually used the residue density in the interferogram as an approximate substitute for the probability of residue occurrence, and then calculated the Pearson correlation coefficients between the ensemble coherence average and the residue density in the corresponding interferogram with several kinds of data from different SAR sensors, including ERS1/2, JERS-1, and Envisat-1 ASAR. The calculation results show a very strong inverse correlation between them, the Pearson correlation coefficients range from -0.702 to -0.963. In other words, the interferometric coherence degree not only can indicate the quality of interferometric phase, but also to a great extent reflect or even predict the density of residues in the interferogram using the linear regression analysis.