Persistent Scatter Identification and Look-Angle Error Estimation Using Similar Time-Series Interferometric Pixels

Abstract

Persistent scatterer (PS) pixels contain highly coherent information, which is used in the estimation of geophysical parameters of interest. Conventionally, PS pixels are selected on the basis of the estimated noise present in the spatially uncorrelated phase component along with look-angle error. The phase history of selected PS pixels is corrected for the look-angle error followed by phase unwrapping and extraction of spatially correlated nuisance phase component leading to displacement estimation. In this letter, a novel PS selection method, which is based on a new index called the similar time-series interferometric pixels (STIPs) representing the number of neighborhood pixels with similar phase history, is proposed. In this approach, apart from PS selection, corresponding set of STIP is also used in refining look-angle error estimation. The efficiency of the proposed InSAR processing chain is demonstrated for the Sentinel-1A single look complex images of Rajmahal, Jharkhand, India, predominantly a coal mines area. Results, when compared with the conventional PS processing technique, reveal substantial improvement in terms of extracting more number of reliable PS with enhanced density.