An Adaptive Bottom Tracking Algorithm for Side-Scan Sonar Seabed Mapping

Whether surveying the lake, river, or ocean, side-scan sonar system is one of the vital instruments in marine science that maps the seafloor for discoveries of shipwrecks, underwater archaeology, and submerged structures; or represents the water column backscattering for researches of marine biology and seagrass measurement. In operation of side-scan sonar survey, determining the altitude of transducer head is critical to avoid collisions between the transducer head and the seabed. On the other hand, determining the altitude of transducer head is namely a technology of bottom tracking. Usually, the bottom tracking inside the sonar software receives the first return acoustic signals from the seabed and computes the depth of the seabed below the transducer head, not from the surface. Moreover, sometimes the first return signals reflected by halobios or ship wake flow caused by propeller churning interferes the result of bottom tracking and determines the wrong altitude of transducer head on the waterfall display. In this paper, an overview of state-of-the-art side-scan sonar bottom tracking technologies is discussed in advance. Afterwards, an adaptive bottom tracking algorithm is introduced to construct a bottom tracking for seabed mapping by means of integrated image processing technologies. Finally, the results show that the adaptive bottom tracking algorithm provides good accuracy of seabed mapping in various geomorphological features.