cluding an area search method by Warnock (1969) and a scan-line algorithm that was developed by Watkins (1970) and constructed into a hardware system. Perhaps the most important breakthrough was Henri Gouraud's development of a simple scheme for continuous shading (Gouraud, 1971). Unlike polygonal shading, in which an entire polygon (a standard surface representation) was a single level of gray, Gouraud's scheme involved interpolation between points on a surface to describe continuous shading across a single polygon, thus achieving a closer approximation of reality. The effect made a surface composed of discrete polygons appear to be continuous.

The work of these individuals alone reflects the high level of fundamental research performed under federal sponsorship in a variety of graphics fields, including surface rendering, simulations, computer animation, graphical user interface design, and early steps toward VR. No less than 11 commercial firms, several of which ship more than $100 million in products annually, trace their origins to the Utah program.⁶