Run-based volume intersection for shape recovery of objects from their silhouettes
Kenji Shoji, Sayaka Sakamoto, Hiroki Iwase, Fubito Toyama, Juichi Miyamichi · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2006
Volume intersection (VI) is a successful technique for reconstructing 3-D shapes from 2-D images (silhouettes) of multiple views. It consists of intersecting the cones formed by back-projecting each silhouette. The 3-D shapes reconstructed by VI are called visual hull (VH). In this paper we propose a fast method obtaining the VH. The method attempts to reduce the computational cost by using a run representation for 3-D objects called SPXY table that is previously proposed by us. It makes cones by back-projecting the 2-D silhouettes to the 3-D space through the centers of the lens and intersects them keeping the run representation. To intersect the cones of multiple views keeping the run representation, we must align the direction of runs representing the cones. To align them we use the method of swapping two axes of a run-represented object at the time cost of O(n) where n is a number of runs, which is also previously proposed by us. The results of experiments using VRML objects such as human bodies show that the proposed method can reconstruct a 3-D object in less than 0.17 s at the resolution of 220 × 220 × 220 voxels from a set of silhouettes of 8 viewpoints on a single CPU.