Angular dependence of acoustic scattering statistics for rocky outcrops

The use of automated detection algorithms in undersea remote sensing and target detection allows for decreased timelines and risk to human assets. However, understanding the performance of these systems requires a thorough understanding of the physical processes that affect the acoustic scattering statistics of the sonar image. Many studies have reported on the scattering statistics of the seafloor generally, and recent work has quantified the dependence of scintillation index on range for sandy seafloors. To date, no studies have examined the angular dependence of acoustic scattering statistics for rocky bottoms, which have more complex spatial texture. This paper analyzes synthetic aperture sonar (SAS) images of rocky outcrops imaged near Bergen Norway to quantify the grazing angle dependency of scattering statistics for rocky seafloors. Outcrops are categorized by texture and analyzed using scintillation index and relative scattering strength with respect to both true grazing angle and a flat seafloor assumption. Comparisons between results utilizing calibrated (beampattern removed) and non-calibrated images will be presented to display the complexity of the grazing angle dependence of scattering statistics for rocky seafloors. SAS imagery provided by the Norwegian Defence Research Establishment. Funding provided by the Office of Naval Research