In this post you can find an overview of two concepts in Papervision: culling and clipping. They are easy to confuse, but both have very important roles.
Culling is the process whereby objects that are not seen by the camera are removed from the rendering pipeline, meaning less polygons for the Papervision engine to have to process.
Clipping is where polygons that extend past the camera are culled, leading to polygons that are still visible (because only part of it is past the cameras view) disappear.
Tutorial is quite informative and detailed. You can view the live demo and download the source code for better practice.
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