Fast bistatic ISAR image generation for realistic cad model using the shooting and bouncing ray technique

Fast inverse synthetic aperture radar (ISAR) image generation, one of the most useful technique in a target recognition, has been studied many times over the past years. Noticeable progress has been made in a fast bistatic ISAR image generation using the shooting and bouncing ray technique (SBR) due to the use of fast Fourier transform (FFT)-based convolution scheme. A FFT-based fast bistatic ISAR imaging scheme using the SBR represents a ray-tube integration in image domain through a convolution between an impulse train function and a ray spread function which is implemented according to an interpolation algorithm and FFT operation. However, the interpolation algorithm which transforms non-uniform impulse train into regular grids causes a distortion of ISAR image owing to artificial transformation of impulse train. Therefore the interpolation algorithm needs to be compensated. In this paper, we demonstrate a bistatic ISAR image generation using the FFT-based fast scheme based on a 1st order Lagrange interpolation algorithm with the extra compensation techniques for a realistic 3D computer-aided design (CAD) model. A comparative study of the ISAR image using the previous direct ray-tube integration method and the Sullivan scheme, one of the typical FFT-based convolution scheme is also included.