Portal Rendering (Paperback)

High Quality Content by WIKIPEDIA articles In computer-generated imagery and real-time 3D computer graphics, portal rendering is an algorithm for visibility determination. For example, consider a 3D computer game environment, which may contain many polygons, only a few of which may be visible on screen at a given time. By determining which polygons are currently not visible, and not rendering those objects, significant performance improvements can be achieved. A portal system is based on using the partitioning of space to form generalizations about the visibility of objects within those spaces. Regions of map space are divided into polygonal, generally convex, areas called sectors. Adjacent sectors are linked to one another via shared dividing polygons termed portals. Approaches that pre-compute visibility for sectors are referred to as potentially visible set or PVS methods.