@inproceedings{ijcai1971p8,
  title     = {Extraction of the Line Drawings of 3-Dimensional Objects by Sequential Illumination From Several Directions},
  author    = {Shirai, Yoshiaki and Tsuji, Saburo},
  booktitle = {Proceedings of the Second International Joint Conference on
               Artificial Intelligence, {IJCAI-71}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {D.C. Cooper},
  pages     = {71--78},
  year      = {1971},
  url       = {https://ijcai.org/proceedings/1971/8},
}