ShieldTester: Cell‐to‐Cell Visibility Test for Surface Occluders

We present a novel Cell‐To‐Cell Visibility (C2CV) algorithm, which given two polyhedra, AandBand a connectedand oriented manifold triangle mesh, S offers a simple, fast and conservative test for detecting when A and B areoccluded from each other by S. Previously disclosed C2CV algorithms either relied on costly occlusion fusion orwere restricted to convex or “apparently convex” occluders, which makes them inappropriate for scenes wherepotential occluders are arbitrary triangulated surfaces, such as the body of a car or a portion of a terrain. Thesimplicity of our C2CV algorithm, named ShieldTester, stems from a new Occlusion Theorem, introduced herewhich permits to establish occlusion by computing the intersection of S with a single ray from a vertex ofAtoa vertex ofB. ShieldTester may be used to establish that pairs of cells in a subdivision of space are hidden fromeach other by a relatively large surface occluder, so that when the viewer is in one cell, the objects in the othercell need not be displayed.

[1]  Werner Purgathofer,et al.  Real-Time Occlusion Culling with a Lazy Occlusion Grid , 2001, Rendering Techniques.

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

[3]  J TellerSeth.  Computing the antipenumbra of an area light source , 1992 .

[4]  A. Safonova,et al.  3D Compression Made Simple: Edgebreaker on a Corner-Table , 2001 .

[5]  Michael Wimmer,et al.  Visibility preprocessing for urban scenes using line space subdivision , 2001, Proceedings Ninth Pacific Conference on Computer Graphics and Applications. Pacific Graphics 2001.

[6]  Daniel Cohen-Or,et al.  Hardware-Accelerated from-Region Visibility Using a Dual Ray Space , 2001, Rendering Techniques.

[7]  Craig Gotsman,et al.  Dynamic Scene Occlusion Culling , 1998, IEEE Trans. Vis. Comput. Graph..

[8]  Jarek Rossignac,et al.  Hoops: 3D Curves as Conservative Occluders for Cell‐Visibility , 2001, Comput. Graph. Forum.

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

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

[11]  Jarek Rossignac,et al.  3D compression made simple: Edgebreaker with ZipandWrap on a corner-table , 2001, Proceedings International Conference on Shape Modeling and Applications.

[12]  Carlos Andújar,et al.  Integrating Occlusion Culling and Levels of Detail through Hardly‐Visible Sets , 2000, Comput. Graph. Forum.

[13]  Daniel Cohen-Or,et al.  A qualitative and quantitative visibility analysis in urban scenes , 1999, Comput. Graph..

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

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

[16]  Michel Pocchiola,et al.  The visibility complex , 1993, SCG '93.

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

[18]  Dirk Bartz,et al.  OpenGL-assisted occlusion culling for large polygonal models , 1999, Comput. Graph..

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

[20]  William S. Massey,et al.  Algebraic Topology: An Introduction , 1977 .

[21]  Frédo Durand,et al.  The 3D visibility complex , 2002, TOGS.

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

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

[24]  Carlos Andújar,et al.  LOD visibility culling and occluder synthesis , 2000, Comput. Aided Des..

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

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

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

[28]  Edwin H. Blake,et al.  Exact From-Region Visibility Culling , 2002, Rendering Techniques.