Study of 3D measurement of ships using dense stereo vision: towards application in automatic berthing systems

Autonomous navigation of ships is actively discussed nowadays. It is essential to recognize the surrounding conditions using radars and acquire position information using GPS. However, each of these existing sensors has its own problems. In order to achieve safer autonomous navigation in scenes such as automatic berthing, passing in a narrow line and closing to other ships, an imaging system that integrates various information is essential. Therefore, the authors propose a 3D position measurement method for ships using a stereo camera. In the case of the automatic berthing system, detailed information such as the position of various parts of the hull, heading, roll angle, etc. is necessary. This paper describes a system that measures 3D locations of many parts of ship’s hull with a dense stereo algorithm applied to stereo-pair images captured by cameras set up on land. An experiment to measure an actual ship as a target was conducted. The result indicated that the more disparity data, which meant depth of the ship from the cameras, were obtained by semi-global matching (SGM) even from the featureless images like ship’s hull and the measurement error was within 1 m.