The role of vision for underwater vehicles

Different sensing techniques have been used for a long time in the development of remote operated vehicles (ROVs) and, in the recent years, autonomous underwater vehicles, (AUVs). Sonar has been the most popular choice in what concerns depth information or obstacle detection in most of the existing systems. Vision, however is a powerful sensing modality and could be used in many tasks where accurate measurements at a short range, are needed. This paper discusses the possible use of vision in the context of autonomous underwater vehicles. Tasks, such as object avoidance or recognition, grasping, docking, sea bed reconstruction, underwater surveillance, inspection, cable maintenance, are among the set of those where computer vision may have an important role. As an example, the authors present a vision system designed for recursive depth estimation based on a underwater vehicle equipped with a camera. Results obtained with underwater images are presented