1.  C=2 (shape from silhouettes)
•Volume intersection [Baumgart 1974]
>For more info:  Rapid octree construction from image sequences. R. Szeliski, CVGIP: Image Understanding, 58(1):23-32, July 1993. (this paper is apparently not available online) or
>W. Matusik, C. Buehler, R. Raskar, L. McMillan, and S. J. Gortler, Image-Based Visual Hulls, SIGGRAPH 2000 ( pdf 1.6 MB )
2.  C unconstrained, viewpoint constraints
•Voxel coloring algorithm [Seitz & Dyer 97]
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3.  General Case
•Space carving [Kutulakos & Seitz 98]
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Voxel coloring solutions