Real-time Tracking of Offshore Vessel Using Pan-tilt Camera for Keeping a Lookout

Abstract

The authors are considering a system to assist a lookout on ships using cameras. In this research, we propose a method of tracking offshore vessels continuously by using a PT (Pan-Tilt) camera. Radar and AIS (Automatic Identification System) are mounted on the ship as equipment to assist a lookout. Radar is essential and widely used in order to obtain information around own ship and find other vessels. However, it is not a perfect device and has some faults, for example, non-detection small vessels under the influence of the noise caused by sea clutter and so on. Also, AIS is not mounted on all vessels and information on AIS is not always trustworthy. In view of these reasons, a lookout by crews is indispensable. But there is a possibility of overlooking and many marine accidents with an insufficient lookout have occurred. We believe that a system that assists a lookout using cameras is thought to be effective in suppressing marine accidents. Previous studies have dealt with wide-angle images when monitoring offshore vessels. On the contrary, zoom images are effective on gazing at a specific vessel or obtaining detailed information, such as bow direction and moving direction. However, the orientation of the camera is necessary to be controlled because the field of view becomes narrow when it zooms. Furthermore, when gazing at the vessels continuously, the orientation of the camera must be directed to the target vessel. Therefore, we propose a fundamental method of controlling the orientation of the camera so that the vessel is located at the center of the image continuously. In this paper, we mainly describe a method to track a vessel on the image sequence, control theory of the camera orientation and the experimental results of real-time camera control to track a vessel.