Shadow Graphs and 3D Texture Reconstruction

  • Authors:
  • Yizhou Yu;Johnny T. Chang

  • Affiliations:
  • Department of Computer Science, University of Illinois at Urbana-Champaign, North Goodwin Avenue, USA;Jet Propulsion Laboratory, Pasadena, USA 91109

  • Venue:
  • International Journal of Computer Vision - Special Issue on Texture Analysis and Synthesis
  • Year:
  • 2005

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Abstract

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.