We present a technique to extract the three-dimensional (3-D) scattering center model of a complex target. Using the shooting and bouncing ray technique, we first generate the 3-D inverse synthetic aperture radar (ISAR) image of the target based on a one-look ISAR algorithm. In step two, we use the image processing algorithm CLEAN to extract the 3-D position and strength of the scattering centers from the 3-D ISAR image. Various implementation issues related to computation time and memory are addressed and an efficient scheme is presented to accomplish the 3-D scattering center extraction. Several examples ranging from simple canonical structures to complex targets are presented to demonstrate the validity of the extraction scheme and the usefulness of the resulting 3-D scattering center model.

Three-dimensional scattering center extraction using the shooting and bouncing ray technique

The shooting and bouncing ray (SBR) method is highly effective in the radar cross section (RCS) prediction. For electrically large and complex targets, computing scattered fields is still time-consuming in many applications like range profile and ISAR simulation. In this paper, we propose a GPU-based SBR that is fully implemented on the graphics processing unit (GPU). Based on the stackless kd-tree traversal algorithm, the ray tube tracing can rapidly evaluate the exit position in a single pass on the GPU. We also present a technique for fast electromagnetic computing that allows the geometric optics (GO) and Physical optics (PO) integral to be carried out on the GPU efficiently during the ray tube tracing. Numerical experiments demonstrate that the GPU-based SBR can significantly improve the computational efficiency of the RCS prediction, about 30 times faster, while providing the same accuracy as the CPU-based SBR.

GPU-Based Shooting and Bouncing Ray Method for Fast RCS Prediction

Ray tracing is of great use for computational electromagnetics, such as the well-known shooting and bouncing ray (SBR) method. In this paper, the kd-tree data structure, coupled with the mailbox technique, is proposed to accelerate the ray tracing in the SBR. The kd-tree is highly effective in handling the irregularly distribution of patches of the target, while the repeatedly intersection tests between the ray and the patch when using space division acceleration structures can be eliminated through the mailbox technique. Numerical results show excellent agreement with the measured data and the exact solution, and demonstrate that the kd-tree as well as the mailbox technique can greatly reduce the computation time.

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Kd-tree based fast ray tracing for rcs prediction

An interior penalty discontinuous Galerkin method is described with a conformal perfectly matched layer (PML) for solving the two first-order Maxwell's equations in the time domain. Both central and upwind fluxes are studied in this work. In both cases, the proposed method is explicit and conditionally stable. Additionally, a local time-stepping strategy is applied to increase efficiency and reduce the computational time. Finally, numerical examples are presented to validate the method.

Interior Penalty Discontinuous Galerkin Finite Element Method for the Time-Dependent First Order Maxwell's Equations

We present an automated technique to extract the three-dimensional scattering-center model of a target from its geometrical CAD model. The technique is based on the shooting and bouncing ray (SBR) method. In this article, we first review the basic concepts behind the three-dimensional scattering-center-extraction algorithm. Next, we present application examples of signature-data compression and radar-feature extraction, based on the scattering centers extracted from complex targets using such a methodology. We conclude by identifying some future areas of research.

3D scattering center representation of complex targets using the shooting and bouncing ray technique: a review

A general method for calculating the radar cross section (RCS) from a three-dimensional target is described. The target is first constructed by using a solid-geometry-modeling computer-aided design (CAD) package. Following the shooting and bouncing ray (SBR) method, a very dense grid of rays is launched from the incident direction toward the target. Each ray is traced according to the geometrical optics theory including the effect of ray tube divergence, polarization, and material reflection coefficient. At the point where the ray exits the target, a physical optics-type integration is performed to obtain the scattered far fields. This method is tested using several simple examples involving interaction among plates, cylinders, and spheres. The theoretical results are generally in good agreement with measured data. >

S.M. Scarborough

Papers

High frequency scattering from trihedral corner reflectors and other benchmark targets: SBR versus experiment