THE ANGULAR DEPENDENCE OF ACOUSTIC SCATTERING STATISTICS FOR ROCKY SEAFLOORS

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Authors
Darling, Lindsey L.
Subjects
synthetic aperture sonar
scattering statistics
image statistics
acoustical properties
remote sensing
acoustics
mixture models
Advisors
Olson, Derek
Date of Issue
2024-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
Understanding the performance of automatic detection algorithms requires a thorough understanding of the physical processes that affect the acoustic scattering statistics of sonar imagery. Many studies have reported on the scattering statistics of the seafloor generally, and recent work has quantified the dependence of scintillation index (SI) on range for sandy seafloors. This study examined the angular dependence of acoustic scattering statistics for rocky seafloors, which display complex spatial texture. Synthetic aperture sonar (SAS) images of rocky outcrops near Bergen, Norway, were categorized by texture and analyzed using scintillation index, relative scattering strength, and mixture model parameters with respect to grazing angle. The different rock textures displayed distinct scattering statistics across all methods of analysis. SI was generally found to increase with decreasing grazing angle and scattering strength was found to increase with increasing grazing angle, though variation was seen between textures. A three component model was found to perform the best for the smooth and weathered/pitted textures whereas a four component model performed the best for the stepped texture. All textures were best represented by less complex models at higher grazing angles, consistent with studies conducted on sandy seafloors. SAS imagery was provided by the Norwegian Defence Research Establishment.
Type
Thesis
Description
Department
Oceanography (OC)
Organization
Identifiers
NPS Report Number
Sponsors
Office of Naval Research, Arlington, VA 22203
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Distribution Statement
Distribution Statement A. Approved for public release: Distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.