Abstract
Autonomous underwater vehicles require accurate knowledge of their position, orientation, and/or motion relative to nearby objects and/or the environment. Passive optical sensing provides useful tools for extracting such information from images. The authors' earlier work involved the development of mathematical models of image formation incorporating effects due to point source illumination and attenuation in the medium. Based on this work, methods are proposed for motion recovery and for the determination of the orientation of planar surfaces. The results of underwater experiments, conducted under controlled conditions in order to demonstrate the validity of some of these methods, are reported.<>