Minimum cost flow phase unwrapping method considering range direction slope

Abstract

In mountainous terrain, the synthetic aperture radar (SAR) interferometry technology causes serious spatial decorrelation due to the shadows and overlaps in the range direction. We propose a minimum cost flow phase unwrapping method considering range direction slope (RDS). The RDS is calculated in the SAR imaging direction, and the RDS is used to divide the high- and low-quality regions of the interferometric phase. In the high-quality area, the residual error between the estimated value of the wrapped phase and the true value is greatly affected by the RDS. The quality map based on the slope in range direction is introduced to limit the number of residuals, at the same time, the quality map is used as the unit cost of the flow to balance the residuals of each node in the minimum cost flow, achieve the minimum cost of the minimum cost flow network, so as to achieve the minimum residual estimation and complete the unwrapping. The phase unwrapping experiments are carried out with the simulated data and the real data from Sentinal-1A in Qinling Mountain in China, and the experimental results show that the root-mean-square error of this method is lower than that of the path tracking method, the least squares method, and the traditional minimum cost flow method. The proposed method is suitable for phase unwrapping in complex mountainous areas.