Exploiting coherence in 2.5-D visibility computation

Visibility computation is used to reduce the amount of geometry that must be passed to the rendering engine. The model is subdivided into subvolumes called “cells”, and the visibility algorithm computes the set of cells that can at least partly be seen from the given viewpoint Airey [Aire90] called this the “potentially visible set” (PVS). The geometry associated with these cells (walls, interior objects) is then displayed, and conventional hidden surface removal (e.g. a Z-buffer) is employed to resolve the actual visibility. Variants of such algorithms have been discussed in [Tell93, Gree93, Lueb95, Nayl95, Yage95].