Instant Visibility

Abstract

We present an online occlusion culling system which computes visibility in parallel to the rendering pipeline. We show how to use point visibility algorithms to quickly calculate a tight potentially visible set (PVS) which is valid for several frames, by shrinking the occluders used in visibility calculations by an adequate amount. These visibility calculations can be performed on a visibility server, possibly a distinct computer communicating with the display host over a local network. The resulting system essentially combines the advantages of online visibility processing and region-based visibility calculations, allowing asynchronous processing of visibility and display operations. We analyze two different types of hardware-based point visibility algorithms and address the problem of bounded calculation time which is the basis for true real-time behavior. Our results show reliable, sustained 60 Hz performance in a walkthrough with an urban environment of nearly 2 million polygons, and a terrain flyover.

More Info

Funding: Austrian Science Foundation  under contract no. P-13867-INF
EU Training and Mobility Researchers network (TMR FMRX-CT96-0036)
Contact: Peter Wonka, Michael Wimmer, François Sillion
in cooperation with iMAGIS - Grenoble
Keywords: Visibility preprocessing, online visibility, occlusion culling, visibility culling, occluder fusion, real-time rendering, urban walkthroughs, urban environments, real-time simulation

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