Shape from Shading Under Coplanar Light Sources

In this paper image-based techniques for 3D surface reconstruction are presented which are especially suitable for (but not limited to) coplanar light sources. The first approach is based on a single-image shape from shading scheme, combined with the evaluation of at least two further images of the scene that display shadow areas. The second approach allows the reconstruction of surfaces by an evaluation of quotients of images of the scene acquired under different illumination conditions and is capable of separating brightness changes due to surface shape from those caused by variable albedo. A combination of both techniques is suggested. The proposed approaches are applied to the astrogeological task of three-dimensional reconstruction of regions on the lunar surface using ground-based CCD images. Beyond the planetary science scenario, they are applicable to classical machine vision tasks such as surface inspection in the context of industrial quality control.