SAR Interferometric Baseline Refinement Based on Flat-Earth Phase without a Ground Control Point

Bing Xu,Guangcai Feng,Zhiwei Li,Jiancun Shi,Yan Zhu

doi:10.3390/rs12020233

Abstract

Interferometric baseline estimation is a key procedure of interferometric synthetic aperture radar (SAR) data processing. The error of the interferometric baseline affects not only the removal of the flat-earth phase, but also the transformation coefficient between the topographic phase and elevation, which will affect the topographic phase removal for differential interferometric SAR (D-InSAR) and the accuracy of the final generated digital elevation model (DEM) product for interferometric synthetic aperture (InSAR). To obtain a highly accurate interferometric baseline, this paper firstly investigates the geometry of InSAR imaging and establishes a rigorous relationship between the interferometric baseline and the flat-earth phase. Then, a baseline refinement method without a ground control point (GCP) is proposed, where a relevant theoretical model and resolving method are developed. Synthetic and real SAR datasets are used in the experiments, and a comparison with the conventional least-square (LS) baseline refinement method is made. The results demonstrate that the proposed method exhibits an obvious improvement over the conventional LS method, with percentages of up to 51.5% in the cross-track direction. Therefore, the proposed method is effective and advantageous.

Highlights

During the past two decades, the interferometric synthetic aperture radar (InSAR) has been gradually matured in terms of theory and widely used in topographic mapping [1] and surface deformation monitoring [2]
In order to obtain an interferometric baseline with a high accuracy and avoid the dependence of the refinement model on ground elevation, this paper firstly investigates the geometry of InSAR imaging and analyzes the rigorous geometric relationship between the interferometric baseline and flat-earth phase in detail
Interferometric baseline estimation is a key procedure of InSAR data processing

Summary

Introduction

During the past two decades, the interferometric synthetic aperture radar (InSAR) has been gradually matured in terms of theory and widely used in topographic mapping [1] and surface deformation monitoring [2]. The accuracy of InSAR is affected by a variety of errors, such as atmospheric delay error, DEM error, random phase error, and baseline estimation error. Among such errors, interferometric baseline estimation error systematically and seriously affects the accuracy of InSAR measurement [7]. The error of the interferometric baseline affects the removal of the flat-earth phase, and the transformation coefficient between the topographic phase and elevation, which will affect the topographic phase removal for D-InSAR and the accuracy of the generated DEM product for InSAR. The present methods of initial baseline estimation make it difficult to obtain high-accuracy baseline estimations due to factors such as the precision of the satellite orbit state vector

Methods

Findings

Discussion

Conclusion