Three-dimensional forward-looking sonar interferometry based on subpixel image registration.

• Focus on three-dimensional interferometry by self-developed forward-looking sonar. • Propose a subpixel image registration algorithm based on a two-dimensional surface. • Reduce the interference of high coherence noise to achieve high accuracy. • Optimize the step search mode in traditional to achieve low computational complexity. • The experiments show the accurate of seafloor bathymetry and 3D target detection. In recent years, three-dimensional forward-looking sonar (3D FLS) has become a research hotspot. Aiming at the problem of image registration in 3D FLS interferometry, this study designs a 3D FLS receiving array using a multi-subarray structure and proposes a subpixel image registration algorithm based on a two-dimensional surface. The amplitude-phase gradient combination criterion is proposed to select the homonymous points. The main advantages of the proposed algorithm are that it can reduce the interference of high coherence noise and achieve high accuracy and low computational complexity. The effectiveness of the proposed method is verified by the simulation and tank experiments using self-developed FLS. The experimental results show that the proposed algorithm can accurately complete seafloor bathymetry and target in the field of view. The proposed algorithm can greatly improve the mapping and surveying efficiency of underwater vehicles, and provide more accurate position information for underwater obstacle. [ABSTRACT FROM AUTHOR]