Shadow Graphs and 3D Texture Reconstruction

We present methods for recovering surface height fields such as geometric details of 3D textures by incorporating shadow constraints. We introduce shadow graphs which give a new graph-based representation for shadow constraints. It can be shown that the shadow graph alone is sufficient to solve the shape-from-shadow problem from a dense set of images. Shadow graphs provide a simpler and more systematic approach to represent and integrate shadow constraints from multiple images. To recover height fields from a sparse set of images, we propose a method for integrated shadow and shading constraints. Previous shape-from-shadow algorithms do not consider shading constraints while shape-from-shading usually assumes there is no shadow. Our method is based on collecting a set of images from a fixed viewpoint as a known light source changes its position. It first builds a shadow graph from shadow constraints from which an upper bound for each pixel can be derived if the height values of a small number of pixels are initialized correctly. Finally, a constrained optimization procedure is designed to make the results from shape-from-shading consistent with the height bounds derived from the shadow constraints. Our technique is demonstrated on both synthetic and real imagery.

Authors and Affiliations

1. Department of Computer Science, University of Illinois at Urbana-Champaign, 201, North Goodwin Avenue, Urbana, IL 61801, USA

   Yizhou Yu

2. Jet Propulsion Laboratory, Mailstop 198-235, 4800 Oak Grove Drive, Pasadena, California, 91109, USA

   Johnny T. Chang

Corresponding authors

Correspondence to Yizhou Yu or Johnny T. Chang.

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