1. Decomposition of a visual scene into three-dimensional bodies;Guzman,1968
2. Impossible objects as nonsense sentences;Huffman,1971
3. On seeing things;Clowes;Artificial Intelligence,1971
4. Understanding line drawings of scenes with shadows;Waltz,1975
5. Interpretation of imperfect line data as a three-dimensional scene;Falk;Arficial Intelligence,1972