Simulation of rippled‐sand sonar imagery with visual and statistical verification.

Abstract

Synthetic aperture sonar (SAS) imagery is often characterized by a decidedly non‐Rayleigh pixel amplitude distribution, owing to its inherent high‐resolution combined with speckle induced by the coherent image formation process. Recent work has shown increasing the resolution cell size by limiting the image bandwidth typically produces images with statistics tending toward a Rayleigh distribution. A caveat to this generalization is that the trend toward Rayleigh is dependent on orientation of the SAS system to strongly correlated sea‐floor structures such as sand‐ripples. A method has been developed to simulate rippled‐sand sonar imagery at high‐frequencies (i.e., on the order of 100 kHz), which accounts for nonsymmetric ripple shape, sediment acoustic properties, sonar to ripple orientation, system resolution, and coherent imaging induced speckle. This numerical simulation method is computationally inexpensive and compares well both visually and statistically with collected data over a wide range of orientation angles. Simulation methods will be presented with verification using SAS imagery collected by the Naval Surface Warfare Center: Panama City Division. [Work supported by ONR Grants No. N00014‐04‐1‐0013 and No. N00014‐06‐1‐0245, and Code 32.]