Effectiveness of 3D PCD Reconstruction using Orthogonal Multiple Sonar Fusion on Frame and Surface type Objects

Recent development of orthogonally-oriented multi-beam sonars fusion (OMSF) has enabled effective reconstruction of underwater 3D point cloud data (PCD) using commonly available acoustic imaging sonars. However, its effectiveness on various object shapes has not been carefully investigated. Addressing such gap is important as underwater structures have varying and complex configurations.This paper investigates the effectiveness of OMSF on three common types of shapes encountered underwater: flat 'hollow' frames, flat 'solid' surfaces, and curved 'solid' surfaces. In-depth analysis of OMSF indicates that its interpolation process tends to fit estimated PCD points onto large surface shapes, leading its PCD results to be more accurate on objects with solid surfaces and not as effective on hollow objects with frames. This analysis is supported by simulation and in-field experiments, with in-field results showing OMSF obtaining up to 60% higher reconstruction accuracy on flat solid surfaces compared to frames with similar outer dimensions.Overall, the analysis and results in this paper shows a limitation of OMSF method for frame-like structures.