Improved Maximum Likelihood Estimation for Optimal Phase History Retrieval of Distributed Scatterers in InSAR Stacks

Changjun Zhao,Bangsen Tian,Zhen Li,Ping Zhang,Shuo Gao

doi:10.1109/access.2019.2961154

Abstract

Distributed scatterer (DS) decorrelation poses a challenge to multibaseline SAR interferometry. To overcome this challenge, the SqueeSAR retrieves an optimal phase time-series using a maximum likelihood estimation (MLE) method, which has been commonly used due to its remarkable effect. Unfortunately, however, the MLE’s performance is compromised for various reasons, such as inaccurate statistically homogeneous pixels (SHPs) and the bias in the estimator used. In this paper, we present an approach aiming to improve the MLE’s performance. The proposed approach includes the employment of the Kullback-Leibler divergence to realize more accurate SHP selection and the use of the second kind statistical estimator to mitigate the coherence bias. The performance of the conventional MLE is significantly improved by the proposed approach, making it close to its optimal performance. The experimental results on both simulated and real TerraSAR-X data demonstrate the improvements of the proposed approach with respect to the conventional MLE.

Highlights

Differential interferometric synthetic aperture radar (DInSAR) has proven to be a high-precision geodetic approach for monitoring the ground surface displacement
SIMULATED EXPERIMENTAL RESULTS Considering the practical scenario of complex ground objects, the simulated scene contains various features that differ in terms of amplitude values
It indicates that the accuracy of statistically homogeneous pixels (SHPs) selection is significant for the maximum likelihood estimation (MLE) phase estimation

Summary

Introduction

Differential interferometric synthetic aperture radar (DInSAR) has proven to be a high-precision geodetic approach for monitoring the ground surface displacement. One major limitation of this technique is the signal decorrelation, which is caused by the changes in the target reflectivity, thermal noise, uncompensated topography, etc. The decorrelation was initially tackled by the persistent scatterer interferometry (PSI) technique [2]–[4]. The basic idea of the PSI technique is to exploit the time-coherent persistent scatterer (PS) with long-time-span differential interferograms. PSs correspond to man-made structures, boulders, and outcrops, making the PSI suitable for urban areas monitoring.

Methods

Results

Conclusion