Development of Underwater Terrain Map Building Method on Polar Coordinates by Using 3D Sonar Point Clouds

This paper proposes the underwater terrain map building method based on the occupancy grids by using 3D point cloud from the polar sonar sensor system. Because it is expensive to use current 3D underwater sonar sensors, the low-cost 3D sensor systems are needed for the generalized purposes. So the polar-styled sonar sensor system was designed and implemented. It was constructed on the rotating motor with the 2D multi-beam sonar image sensor. And we developed the depth map model based on an occupancy probability grids map using the Bayesian-updating model. This way could reduce the noise caused by fundamental characteristics of a sonar sensor. The experiment was conducted to verify the validity and the usefulness of the proposed approach.