In many applications, such as automotive, industrial, architectural, and graphic design, and whenever effective communication is the goal, illustrations have certain advantages over photorealism. They convey information better by omitting extraneous detail, by focusing attention on relevant features, by clarifying, simplifying, and disambiguating shapes, and by showing parts that are hidden. Illustrations also provide a more natural vehicle for conveying information at different levels of detail. In many respects, illustrations are also more attractive: they add a sense of vitality difficult to capture with photorealism.

In this talk, I will discuss a variety of algorithms for creating non-photorealistic illustrations automatically, starting from continuous tone images, three-dimensional computer graphics models, or communications from an on-line "chat room" as input. Our early results, published in eight papers at SIGGRAPH over the last four years, include, among other things, support for resolution-dependent pen-and-ink rendering, in which the choice of strokes used to convey both texture and tone is appropriately tied to the resolution of the target medium; the automatic "watercolorization" of source images; a system for representing on-line communications in the form of comics; and an approach for simulating apparent camera motion through a 3D environment using a moving window over a single 2D background image.