Simulation of multiple-receiver, broad-band interferometric SAS imagery

Interferometric synthetic aperture sonar (InSAS) is a technique for high-resolution, 3-dimensional underwater imaging. A significant problem in developing and testing InSAS algorithms is the difficulty in obtaining ground-truth data to compare with the reconstructed imagery/bathymetry. Thus, a reliable simulation model is a useful aid. Most SAS simulation models are based on a point-scatterer representation of the underwater scene. The point-scatterer model is computationally inefficient for simulating large, realistic scenes. Furthermore, effects such as aspect-dependent scattering, speckle, shadowing, and multiple-scattering are not replicated easily. In this paper we present an efficient model for the realistic simulation of multiple-receiver InSAS imagery. The model is based on a facet representation of the underwater scene. The field scattered by each facet is realised using statistics determined by the Kirchoff method and occlusions and multiple-scattering are resolved by ray-tracing. The simulation of InSAS imagery is demonstrated using the parameters of our Kiwi-SAS system. The simulated imagery is shown to include the characteristic effects of aspect-dependent scattering, speckle, and shadowing.