Challenges in Coregistration of Repeated Passes in Synthetic Aperture Sonar

Synthetic aperture sonar (SAS) is a technique for high resolution imaging, similar to synthetic aperture radar (SAR). In SAR, repeat pass interferometry, tomography, and coherent change detection are today established as standard methods. This is not true for SAS, where coregistration for coherent combination from repeated passes is a major challenge. Many factors may cause misregistration, including insufficient navigation accuracy, variability in the ocean environment, and nonideal tracks. In this paper we describe the challenges in coregistration, and evaluate a re-imaging scheme including corrections on real data collected by a HUGIN autonomous underwater vehicle carrying a HISAS interferometric SAS.