Acoustic and visual instrumentation for survey of manganese crusts using an underwater vehicle

This paper describes the application of acoustic and visual instruments developed to survey the volumetric distribution of manganese crusts from an underwater vehicle. The instruments consist of an acoustic device, used to measure the thickness manganese crust layers, and a visual mapping system that generates three-dimensional (3D) color reconstructions of the seafloor. The information obtained by these sensors is processed to automatically identify areas of exposed crust using the 3D reconstructions, and determine the thickness of the crusts based on the acoustic measurements to measure the volumetric distribution of manganese crusts. Continuous measurements of crust distribution were achieved for the first time using the instruments described during sea trials performed at #5 Takuyo seamount using the remotely operated vehicle Hyper-Dolphin.