Efficient 3D Image Reconstruction of Airborne TomoSAR Based on Back Projection and Improved Adaptive ISTA

Dong Han,Liangjiang Zhou,Bingnan Wang,Yachao Wang,Yirong Wu,Zekun Jiao

doi:10.1109/access.2021.3066984

Abstract

Airborne SAR tomography (TomoSAR) 3D image reconstruction can be realized with combination of 2D imaging algorithms and compressed sensing (CS) algorithms. However, most typical CS algorithms cannot achieve a balance between algorithm efficiency and 3D reconstruction accuracy. Due to difficulties in flight path control of airborne SAR, it is hard to realize registration of SAR images with frequency-domain imaging algorithms because of time-varying baseline. To address these problems, an efficient 3D image reconstruction method for airborne TomoSAR based on back projection (BP) algorithm and improved adaptive iterative shrinkage-thresholding algorithm (IA-ISTA) is proposed. First, 2D images are achieved with BP algorithm on the ground plane. After registration of SAR images, 3D image reconstruction results in the elevation direction are realized with IA-ISTA. Selection criterion of IA-ISTA parameters are given in this paper. At last, final 3D image reconstruction results are achieved after geometrical transformation based on geometric relationship. Both simulated data and measured data of a P-band airborne TomoSAR system are used. 3D image reconstruction results show that the proposed method outperforms traditional methods regarding efficiency and accuracy, which proves the validity and practicality of the proposed method.

Highlights

Due to SAR imaging mechanism, there are serious problems of layovers and shadows, which hinder the interpretation, application, and development of SAR remote sensing
We propose an improved adaptive iterative shrinkage-thresholding algorithm (ISTA) (IA-ISTA) in 3D image reconstruction of airborne SAR tomography
IMPROVED ADAPTIVE ISTA Compared with traditional ISTA, proposed iterative shrinkage-thresholding algorithm (IA-ISTA) can be applied as a superior 3D image reconstruction algorithm for airborne SAR tomography because of both having accurate reconstruction results and better algorithm efficiency

Summary

INTRODUCTION

Due to SAR imaging mechanism, there are serious problems of layovers and shadows, which hinder the interpretation, application, and development of SAR remote sensing. B. IMPROVED ADAPTIVE ISTA Compared with traditional ISTA, proposed IA-ISTA can be applied as a superior 3D image reconstruction algorithm for airborne SAR tomography because of both having accurate reconstruction results and better algorithm efficiency. Considering unambiguous height in the elevation direction of airborne TomoSAR [23], we choose chirp signals at L-band for simulation with carrier frequency f0 = 1.5GHz. Simulated observation geometry consists of 11 linear trajectories with average look angle α = 45◦. With processing chain of proposed IA-ISTA illustrated, TomoSAR 3D image reconstruction problem can be solved with the following modificated iterations xknew (24). After 3D image reconstruction with proposed IA-ISTA, final TomoSAR 3D image reconstruction results can be achieved with geometrical transformation by using (8), (9), and (10)

ANALYSIS OF RESOLUTION

RESULTS OF SIMULATED BUILDING

CONCLUSION