“Hidden line removal for vector graphics” by Wein, Tanner, Bechthold and Burtnyk

  • ©Marceli Wein, Peter P. Tanner, G. Bechthold, and Nestor Burtnyk




    Hidden line removal for vector graphics



    A system for removing hidden edges in line displays of three dimensional scenes is described. The hardware system is relatively low cost, and operates on several hundred vectors in real-time. The system consists of a graphics peripheral connected to a PDP 11/55 computer and a software package to drive the peripheral. As each convex object is displayed, the occlusion hardware extracts the silhouette and retains it in a one-plane “matte memory”. As subsequent objects, taken from a priority ordered list, are displayed, the vector generator tests the contents of the frame buffer at the coordinates along the vector. The contents of the matte memory determine which portions of the vector should be intensified. To produce the priority ordered list of objects, the software algorithm uses three ordering techniques applied selectively to different potions of the scene. One technique, used for ordering unconstrained pairs of objects is described in detail.


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