2023_programme: Challenges in synthetic aperture sonar imaging of shipwrecks for change detection

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  • Session: 15. Towards Automatic Target Recognition. Detection, Classification and Modelling
    Organiser(s): Johannes Groen, Yan Pailhas, Roy Edgar Hansen, Jessica Topple and Narada Warakagoda
  • Lecture: Challenges in synthetic aperture sonar imaging of shipwrecks for change detection [invited]
    Paper ID: 1987
    Author(s): Hansen Roy Edgar
    Presenter: Hansen Roy Edgar
    Abstract: After World War II (WWII) large amounts of chemical munitions were dumped in the Skagerrak strait in Norwegian waters. The approach was to fill decommissioned cargo ships with the chemical munitions, and then sink the ships in a designated area. In 2015 and 2016, the Norwegian Defence Research Establishment (FFI) conducted a large area search to detect all shipwrecks part of the dumpsite, and judge their conditions. The equipment was FFIs HUGIN autonomous underwater vehicle (AUV) carrying a HISAS synthetic aperture sonar (SAS). In 2019 and 2022, several of the wrecks were revisited using the same equipment. \nThe condition of each of the shipwrecks is varying, and there is a chance that aging and decay may cause structural changes to the wrecks that again may cause leakage of chemical munitions substances from the cargo bays to the surrounding ocean environment. A potential tool for monitoring the conditions of the shipwrecks over many years is AUV-based SAS in combination with image based Change Detection (CD). For successful use of this technique, the CD must be high resolution, reliable and automated. \nIn this paper, we describe the requirement for track quality, track repeatability, and image quality in order to perform image based CD on shipwrecks. We describe SAS image artefacts caused by non-straight data collection tracks in combination with large three-dimensional structures on the seafloor, how these artefacts may cause false positives in CD, and potential techniques to mitigate these artefacts. We demonstrate our techniques on data collected by FFIs HUGIN AUV from 2015, 2019 and 2022.
      Download the full paper
  • Corresponding author: Prof Roy Edgar Hansen
    Affiliation: Norwegian Defence Research Establishment (FFI)
    Country: Norway
    e-mail:

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