Fast ISAR Image Formations Over Multiaspect Angles Using the Shooting and Bouncing Rays

Synthetic aperture radar automatic target recognition (SAR ATR) is a powerful tool for recognizing targets. The SAR ATR needs a massive database of inverse synthetic aperture radar (ISAR) images from computer-aided design (CAD) models for multiple aspect angles. To rapidly build the multiview database, we present a fast method to simulate the ISAR images over multiple aspect angles using the shooting and bouncing ray technique. Compared to the previous fast method where a ray-tracing process must be performed at each aspect angle of the ISAR images, the proposed method generates the ISAR images over multiple aspect angles through only a one-time ray-tracing process at an arbitrary angle. Therefore, the computation time is decreased as much as the number of ray-tracing processes is decreased. Similar to the previous fast method, the proposed method should be used under small angle conditions for perfect electric conductor (PEC) CAD models with a sufficiently smooth surface. The ISAR images of a tank CAD model are simulated over multiple aspect angles to verify the performance of the proposed method.