Fusion of AUV-Mounted 360-Degree Underwater LiDAR and Side Scan Sonar Data

Recent advancements in mapping coastal waters have birthed underwater bathymetric LiDAR systems, addressing the limitations of energy loss through the interaction of light with the air-water interface by Airborne bathymetric LiDAR systems. This study introduces an innovative and compact underwater 360° Pulsed Laser Line Scanner (PLLS-360°) system. This system boasts a 360° scanning angle and a 360° field-of-view (FOV) receiver, providing its ability to map the seafloor, water column, and water surface simultaneously thereby enhancing its utility in various scenarios. The PLLS-360° is suitable for diverse applications such as seafloor mapping, underwater asset inspection, and construction progress monitoring. The LiDAR system is integrated with an Iver3 AUV equipped with an interferometric side scan sonar (SSS) allowing LiDAR-sonar data fusion. A test involving mapping an artificial reef site at the Blue Heron Bridge in Florida, was carried out. The acquired LiDAR raw waveforms were corrected for spreading loss as the light returned from the target to the LiDAR receiver. The peak intensities of the corrected waveforms were detected, and the ranges were calculated from the peak position. The range was corrected for the AUV motion and georeferenced to obtain the final bathymetry. The sonar image and bathymetric data were fused, providing a more detailed description of the seafloor.