The Frontier

The frontier is a curve that separates the visible from invisible region - at least locally - for a given camera motion. In the following video we show the visible region sweeping out the surface. But notice that near the top of the surface the contour generators do not sweep across the surface but in fact form an envelope.

Frontier MPEG(182k)

Frontier point for these two viewpoints.

We can of course consider many frontier points.

Animation MPEG

Profiles of complex scene MPEG

Jump here.
for singularities.
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