Fast SAR Image Simulation Based on Echo Matrix Cell Algorithm Including Multiple Scattering

Abstract

We present a novel fast synthetic aperture radar (SAR) image simulation method based on the echo matrix cell algorithm including multiple scattering. To improve the efficiency of SAR image simulation while ensuring the fidelity of the simulated results, we first discretized the target facets set in the SAR beams footprint into lattice targets using the range-Doppler (RD) imaging geometry model and provided the basis for simulating electromagnetic wave transmission. Based on the simulation of electromagnetic waves transmission, we used the ray tracing algorithm to calculate the multiple backscattering field including multi-polarimetric information and various material properties. Then, based on the echo matrix cell algorithm, we set the echo matrix cell as the subfield of the target backscattering field and designed the CUDA kernel function to implement a computation parallelization for SAR echo generation. All the echo matrix cells are traversed in parallel to obtain the total backscattering field of the target, reproducing the time-varying characteristic of the backscatter coefficient for each lattice target within the synthetic aperture time. The echo signal is processed using the RD imaging algorithm to obtain the simulated SAR image. Finally, we select some targets including aircraft carrier and airplane models for simulation tests. The computation efficiency is improved over 170-fold by comparing the computations of the proposed method and CPU single-thread. We also performed some qualitative and quantitative evaluations on the fidelity of the simulated SAR images. The experimental results verify the effectiveness of the proposed method.

Bounding Volume Hierarchy-Assisted Fast SAR Image Simulation Based on Spatial Segmentation

“…Usually, the depolarization effect is generated throughout the multiple scattering processes of the EM wave and the target backscatter field calculation is chosen to be carried out in the local coordinate system, while the target backscatter field in the global coordinate system is recorded by the sensor, and the depolarization effect can be represented in the process of the conversion between the local scattering coordinate system and the global transmitting coordinates. Because the above polarization coordinate system conversion is not the focus of this paper, we only briefly describe the functional relationship between the polarimetric scatter coefficient, the local incident angle, and the relative permittivity; the detailed derivation process can be referred to our previously published article [16]. Parallel or vertically polarized incident waves in the local coordinate system can only produce horizontally or vertically polarized reflective waves, and according to the boundary condition of continuity of the tangential component of the EM field at the interface of the incident and reflective wave components, we can represent the polarization effect in the global coordinate system and express the vertically and horizontally polarized scattering coefficients at the intersection of the first scattering in the local coordinate system by Equation (8).…”

“…Chiang et al combined POs and GOs to carry out the target multiple backscatter field calculation, combined them with the frequency domain echo model to generate the original echo signals, acquired the tank SAR data set by focusing imaging processing, and achieved better simulation results [14]. Wu et al based on the physical illumination model of high-frequency ray theory, carried out the echo-based SAR image simulation on a typical military target to achieve some good simulation results, and then a fast simulation architecture based on the CUDA was established to effectively improve the efficiency of the SAR image simulation [15,16]. Balz et al utilized an improved physical illumination model to simulate the SAR image of a 3D scene and used the GPU to simulate the multiple scattering effects of the EM wave in multi-thread parallel, achieving a good result and better simulation results [17].…”