Y. Ansel Teng David M. Mount Enrico Puppo Larry S. Davis Parallelizing and Algorithm for Visibility on Polyhedral Terrain. 75-84 1997 7 Int. J. Comput. Geometry Appl. 1/2 db/journals/ijcga/ijcga7.html#TengMPD97 http://dx.doi.org/10.1142/S0218195997000065