Two Simple Algorithms For Displaying Orthographic Projections of Surfaces

Abstract

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.