RULED TRACING

The traditional ray-tracing technique based on a ray-surface intersect ion is reduced to a ruled or developable. surface-surface intersection problem, That enables direct freeform surface rendering, By exploitin g the spatial coherence gained in the ruled/developable surface-tracin g approach presented, the emulation of shadows, specular reflections, and/or refractions in a freeform surface environment can all be implem ented efficiently. The approach provides a direct freeform surface-ren dering alternative to ray tracing. An implementation of a direct freef orm surface renderer that emulates shadows as well as specular reflect ions is discussed. This renderer processes isoparametric curves as its basic building block, eliminating the need for polygonal approximatio n.