Dynamic Stabilization of a Pan and Tilt Camera for Submarine Image Visualization

One major problem of underwater observation with an automatic engine is the instability of image acquisition and visualization. Indeed, small engines of this kind are subjected to low-frequency motions due to weak friction and water currents. In this paper, we propose to maintain stabilization in the image by controlling the pan and tilt motions of the camera attached to the engine, using techniques for target tracking by visual servoing. The main idea behind approach lies in the fact that, since it is very difficult to track a point in the images of an unknown and complex scene using geometrical tools, the position of a virtual point can be retrieved by the integration of its 2D motion. The motion estimation method we have used, called the RMR algorithm, provides the parameters of a selected motion model (for the task considered here, a constant one) and is perfectly suitable for real-time constraints and the complexity of an undersea image sequence. Our approach has been validated on a dry setup using two different sequences of underwater images.