Applicability and improvement of underwater video mosaic system using AUV

In various inspections for the construction and the maintenance of port facilities, the underwater observation is a very important and an effective method. In general, the view of underwater video images is narrowly limited due to the turbidity of the sea water and the camera field angle. Therefore, the data processing such as mosaicing is necessary to observe the object over the wide range. However, the automization of mosaicing work is difficult, because of the insufficiency of the position information about underwater images. We have proposed an efficient mosaicing system of underwater images using AUV (autonomous underwater vehicle) mounting the video camera with the line-laser. It is preferable to take a movie from the same direction by a constant distance as much as possible to make an accurate mosaicing image efficiently. In proposed system, the attitude of AUV is controlled based on the distance and the inclination to the object calculated from the position of the laser line in obtained images. To make mosaicing image by proposed method, the image of the port structure with the laser line is acquired in a real sea area. And, the affine transformation, the projective transformation, and the method of using information about the laser line are used as a transformation method of images extracted from a movie of an actual port structure. In this paper, applicability and the improvement method of mosaicing procedure are discussed by comparing mosaicing images obtained by these methods.