Vision‐based markerless measurement system for relative vessel positioning

The measurement of relative vessel positioning is important to prevent the risk of vessel collision or the deterioration of working efficiency. This study presents a vision‐based system for measuring the relative position and heading between a vessel and a target object without the installation of transponders, reflectors, or markers. Such a markerless measurement system, which is not restricted by the presence or the absence of transponders, is a method of expanding feasible conditions for relative vessel positioning. The proposed system consists of multiple camera units that can measure the distance and direction between an initially designated point on a target object while keep track of the designated point. To evaluate the measurement performance for the proposed system, the authors conducted measurements by using a prototype system in water. The results demonstrated that the system can keep track of the designated points and accurately measure the position and heading of a vessel relative to a target object, despite the vessel's roll motion.