Correcting Ship-Track Orthogonal Bathymetric Undulations Induced by Lever Arm Errors in Multibeam Echosounder Bathymetric Data

Multibeam echosounder systems have been becoming a standard acoustic remote sensing approach and are widely applied in ocean mapping tasks. The errors of lever arm between heave sensor and transducer due to deformation or mistaken measurement will be manifested as ship-track orthogonal bathymetric undulations, which will hinder the accurate expression of high-resolution seafloor topographic maps. To address this issue, in this article, the characteristics of lever arm errors and the distinction from other errors are analyzed, and a new method is proposed to calibrate the lever arm errors. First, the periodical pattern of abnormal undulations caused by lever arm errors is extracted by the Two-Way Difference Method and Multistart Algorithm. Then, the correction model is established and the Random Sample Consensus Algorithm with moving windows is used to obtain the correction water depth. Finally, support vector regression is used to calculate the lever arm errors with the correction depth and initial depth. The results indicate that the proposed method can significantly eliminate ship-track orthogonal bathymetric undulations in multibeam bathymetry caused by lever arm errors and is robust in complex seabed topography.