Ground deformation monitoring of Zhengzhou city from 2012 to 2013 using an improved IPTA

To address the low efficiency of interferometric point target analysis for processing high-resolution SAR data, this paper proposes a novel thinning method for interferometric point target and an improved filtering method to reduce the large-scale atmospheric phase delay. The thinning method is used to ensure the quality of PS point based on point density, by which points in low-density area are kept, while redundant points in high-density area are removed. Analyzing thinned PSs is helpful in quickly obtaining the initial atmospheric delay, which facilitates the temporal phase unwrapping and promotes the efficiency of parameter calculation. Meanwhile, this paper proposes a filtering method for large-scale atmospheric phase delay with the fusion of multi-looking, spatial filtering and spatial interpolation methods. This method is simple and quick, compared with traditional spatial filtering methods. The case study of Zhengzhou city from 2012 to 2013 verifies that this method doubles the efficiency of the traditional data processing methods. Also, the precision of deformation velocity in this case study is up to 3.16 mm/a based on the comparison with the ground leveling measurement.