3D shape recovery of non-convex object from rotation

We propose a method for estimation of the 3D shape of a non-convex object from an image sequence taken with the object rotating under a fixed light source. First, all the territory candidates of the object are prepared in voxel space. The empty voxels are selected by using cross-section estimation using a silhouette, that is the conventional method. However this method cannot reconstruct the non-convex object, because change isn´t shown in the silhouette by the dents. Therefore, we remove part of the dents by using the cross-section estimation using occlusion and shading. For the cross-section estimation using occlusion, we apply a technique similar to the shape from silhouette. That is to say, the ray connects the point of view and occlusion to the tangent toward the front object of occlusion and removes the territory surrounded by the corresponding two tangents of the two neighboring views. For the cross-section estimation using shading, we decide the most suitable position of the surface point in the searched ray, which connects a point of view and the surface and on which the surface point is searched. To decide a suitable position, we examine a change in brightness of backward rays, which connect a voxel and each point of view. At each voxel on the searched ray, the most suitable position is where the degree of agreement with the bi-directional reflectance model is the highest. For demonstrating the effectiveness of the proposed method, we show the reconstructed image of non-convex objects, such as balls, or a doll and chair, which are successfully recovered