• visual hull method;
  • photometric stereo;
  • depth map


The authors propose a method to measure the smooth curved surface of an object and the depressed surface of an object which cannot be measured using the visual hull method by using a needle diagram obtained via photometric stereo. Errors occur in the distance map as a result of depth edges when recovering a distance map using a needle diagram. In order to reduce these errors, the silhouettes from other directions are used. The distance map restored without taking into consideration the depth edges often lacks consistency with the silhouettes obtained from other directions. The authors take advantage of this feature, define the energy representing the consistency between the distance map and the silhouette as well as the consistency between the distance map and the needle diagram, and then reduce the errors in the distance map by obtaining a distance map which minimizes this energy. Through experiments using the proposed method on simulation data and a real object, the authors evaluate the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(14): 29–40, 2007; Published online in Wiley InterScience ( DOI 10.1002/scj.20763