Computation of stereo disparity for space materials

One of the challenges facing computer vision systems used in space is the presence of specular surfaces. Such surfaces lead to several adverse effects when imaged by vision systems such as the creation of reflected “virtual” images of objects due to specular reflections, specular reflection of light from the sun and other sources, and total reflection of any projected illuminants including laser beams. These effects may lead to incorrect measurements and loss of data in the case of sensor saturation or inadequate intensity of the returned laser beams in the case of an active illuminant. In addition, the instruments inside space structures such as satellites may be extremely sensitive to active illuminants such as laser beams or radar signals, and thus passive vision systems which rely on either natural on low-power projection systems are preferred over active sensing technologies. An additional advantage of fixed stereo based techniques over scanning rangefinders lies in the fact that fixed stereo systems do not contain moving parts that are prone to failure and expensive to qualify for space and maintain. Fixed stereo based systems use cameras, framegrabbers and computers already qualified for space but must deal with the issue of specular reflections. Here we consider the task of recovering the local surface structure of highly specular surfaces such as satellites using passive stereopsis without resulting to the introduction of additional light sources. In particular we examine the use of stereo cameras to recover surfaces which result in perfectly specular reflection.