Instant Visibility

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.

[1]  Frédo Durand,et al.  3d visibility: analytical study and applications , 1999 .

[2]  Dieter Schmalstieg,et al.  Occluder Shadows for Fast Walkthroughs of Urban Environments , 1999, Comput. Graph. Forum.

[3]  Carlo H. Séquin,et al.  Adaptive display algorithm for interactive frame rates during visualization of complex virtual environments , 1993, SIGGRAPH.

[4]  Dinesh Manocha,et al.  Visibility culling using hierarchical occlusion maps , 1997, SIGGRAPH.

[5]  Dinesh Manocha,et al.  Accelerated occlusion culling using shadow frusta , 1997, SCG '97.

[6]  Daniel G. Aliaga,et al.  MMR: an interactive massive model rendering system using geometric and image-based acceleration , 1999, SI3D.

[7]  David P. Luebke,et al.  Portals and mirrors: simple, fast evaluation of potentially visible sets , 1995, I3D '95.

[8]  John Amanatides,et al.  Merging BSP trees yields polyhedral set operations , 1990, SIGGRAPH.

[9]  Seth J. Teller,et al.  Real-time occlusion culling for models with large occluders , 1997, SI3D.

[10]  Vlastimil Havran,et al.  Hierarchical visibility culling with occlusion trees , 1998, Proceedings. Computer Graphics International (Cat. No.98EX149).

[11]  Arno Formella,et al.  FAST PENUMBRA CALCULATION IN RAY TRACING , 1998 .

[12]  Carlo H. Séquin,et al.  Visibility preprocessing for interactive walkthroughs , 1991, SIGGRAPH.

[13]  François X. Sillion,et al.  Conservative volumetric visibility with occluder fusion , 2000, SIGGRAPH.

[14]  James H. Clark,et al.  Hierarchical geometric models for visible surface algorithms , 1976, CACM.

[15]  James H. Clark.  Hierarchical geometric models for visible-surface algorithms , 1976, SIGGRAPH 1976.

[16]  Pere Brunet,et al.  The visibility octree: a data structure for 3D navigation , 1999, Comput. Graph..

[17]  Joëlle Thollot,et al.  Conservative visibility preprocessing using extended projections , 2000, SIGGRAPH.

[18]  Michael Wimmer,et al.  Visibility Preprocessing with Occluder Fusion for Urban Walkthroughs , 2000, Rendering Techniques.

[19]  David H. Laidlaw,et al.  Constructive solid geometry for polyhedral objects , 1986, SIGGRAPH.

[20]  Gavin S. P. Miller,et al.  Hierarchical Z-buffer visibility , 1993, SIGGRAPH.

[21]  Daniel Cohen-Or,et al.  Conservative Visibility and Strong Occlusion for Viewspace Partitioning of Densely Occluded Scenes , 1998, Comput. Graph. Forum.

[22]  Daniel Cohen-Or,et al.  Virtual Occluders: An Efficient Intermediate PVS Representation , 2000, Rendering Techniques.

[23]  Tiow Seng Tan,et al.  Preprocessing occlusion for real-time selective refinement , 1999, SI3D.