In graphics, backface culling is the process by which the faces of a mesh that are facing away from a particular direction (e.g. camera) are culled in some form so that we avoid or reduce the GPU cost of processing them.
- detailed culling, i.e. test each face individually and see if it's culled
- coarse culling, i.e. work out a conservative cone of directions that can be culled and cull faces based on that.
Red (cull) / Green (visible) circles on bounding box boundaries show extremes. Circle in the middle shows the combined (conservative) cull cone.
Coarse culling done by looking at bounding box and assuming any face direction can appear anywhere within that box. That's conservative (i.e. actual model will probably have a different distribution of faces) but allows for quick rejection.
Can split mesh into clusters, based on average face direction. Store average face direction + cone per cluster.