Two Simple Algorithms for Displaying Orthographic Projections of Surfaces

Two simple algorithms are described for displaying orthographic projections of surfaces. The first, called RELIEF-PLOT, produces a three-dimensional plot of a surface z = f(x,y). The second, called SHADED-IMAGE, adds information about surface reflectivity and source illumination to produce a grey level image of a surface z f(x,y). Both algorithms demonstrate how a systematic profile expansion can be used to do hidden surface elimination essentially for free. Work reported herein was conducted at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defence under Office of Naval Research Contract number N00014-75C-0643