J. Geurts, J. van Ossenbruggen, and L. Hardman. Proceedings of the International Conference on Multimedia Modeling 2001 (MMM01), page 247-266. CWI, Amsterdam, The Netherlands, (November 2001)
S. Nayar, X. Fang, and T. Boult. Computer Vision and Pattern Recognition, 1993. Proceedings CVPR '93., 1993 IEEE Computer Society Conference on, (15-17 Jun 1993)