利用梯度重建的稳健多频InSAR相位解缠方法

A Robust Multi-frequency Phase Unwrapping Method Based on Gradient Reconstruction

为解决常规InSAR系统因干涉相位欠采样所导致的陡峭地区高程提取困难问题,提出一种利用多频干涉量进行相位梯度重建并实现相位解缠的处理方法。基于干涉相位的统计分布特性,研究了多频InSAR相位梯度的最大似然估计原理,针对有限观测频点情况下梯度解模糊性能对相位噪声敏感的问题,提出通过基于邻点集的局部曲面建模进行相位梯度重建的稳健算法,并从频点选择、估计区间限定等方面进一步研究了提高算法稳健性的途径。最后通过对仿真和实际DEM数据的试验,验证该方法的有效性。

In order to address the difficulties in elevation extraction for rugged terrain due to phase undersampling by conventional InSAR system, a phase unwrapping method supported by phase-gradient reconstruction from multifrequency interferograms is presented. Based on statistical distribution property of wrapped phase, a maximum likelihood estimation technique using multi-frequency phase-gradient is investigated first. Considering the problem of high sensitivity to phase noise under limited number of frequencies in resolving gradient ambiguity, an improved phase-gradient estimation algorithm based on local surface modeling within neighborhood set is presented, and the way to enhance the robustness is further studied from aspects of frequency selection, estimation interval restriction and so on. Finally, experiments using simulated and real DEM data are performed respectively, and the results confirm the validity of the proposed method.