Shape reconstruction of 3D bilaterally symmetric surfaces

The paper presents a new approach for shape recovery based on integrating g eometric and photometric information. We consider 3D bilaterally symmetric objects, that is, objects which are symmetric with respect to a plane (e.g. , faces), and their reconstruction from a single image. Both the viewpoint and the illumination are not necessarily frontal. Furthermore, no correspon dence between symmetric points is required. The basic idea is that an image taken from a general, non frontal viewpoint , under non-frontal illumination can be regarded as a pair of images. Each image of the pair is one half of the object, taken from different viewing p ositions and with different lighting directions. Thus, one-image-variants o f geometric stereo and of photometric stereo can be used. Unlike the separa te invocation of these approaches, which require point correspondence betwe en the two images, we show that integrating the photometric and geometric i nformation suffice to yield a dense correspondence between pairs of symmetr ic points, and as a result, a dense shape recovery of the object. Furthermo re, the unknown lighting and viewing parameters, are also recovered in this process. Unknown distant point light source, Lambertian surfaces, unknown constant a lbedo, and weak perspective projection are assumed. The method has been imp lemented and tested experimentally on simulated and real data.