A Non-Photorealistic Lighting Model For Automatic Technical Illustration
Author(s): Amy A. Gooch, Bruce Gooch, Peter Shirley, Elaine Cohen.
Proceedings: SIGGRAPH 98, pp. 447--452, July,
1998.
[BibTeX] [DOI] 
Abstract:
Phong-shaded 3D imagery does not provide geometric information
of the same richness as human-drawn technical illustrations. A
non-photorealistic lighting model is presented that attempts to narrow
this gap. The model is based on practice in traditional technical
illustration, where the lighting model uses both luminance
and changes in hue to indicate surface orientation, reserving extreme
lights and darks for edge lines and highlights. The lighting
model allows shading to occur only in mid-tones so that edge
lines and highlights remain visually prominent. In addition, we
show how this lighting model is modified when portraying models
of metal objects. These illustration methods give a clearer picture
of shape, structure, and material composition than traditional computer
graphics methods.