@article{Shirai:1972:ELD,
  optpostscript = {},
  number = {4},
  month = dec,
  author = {Yoshiaki Shirai and Saburo Tsuji},
  optkey = {},
  optannote = {},
  localfile = {papers/Shirai.1972.ELD.pdf},
  optkeywords = {},
  doi = {http://dx.doi.org/10.1016/0031-3203(72)90034-9},
  optciteseer = {},
  journal = {Pattern Recognition},
  opturl = {},
  volume = {4},
  optwww = {},
  title = {{E}xtraction of the {L}ine {D}rawing of 3-{D}imensional {O}bjects by
           {S}equential {I}llumination from {S}everal {D}irections},
  abstract = {The conversion of a three-dimensional physical scene to a
              line-drawing is made more reliable by using information obtained
              by illuminating the scene, sequentially, from several different
              directions. By applying two-dimensional logical operations to the
              separately obtained pictures, one can eliminate many of the bad
              effects of poor edge contrast (due to too small difference of
              illumination of two planes) and of shadows. The method gives
              better results on scenes containing many overlapping polyhedra
              than are obtained by conventional one-picture edge-finding
              methods. The basic operations are OR, which extracts lines
              contained in either drawing and AND, which finds lines contained
              in both. The project is part of the programming for the ETL-ROBOT,
              an intelligent hand-eye automaton being developed at the
              Electrotechnical Laboratory. },
  pages = {343--351},
  year = {1972},
}