Ray space factorization for from-region visibility

Tommer Leyvand*, Olga Sorkine, Daniel Cohen-Or

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


From-region visibility culling is considered harder than from-point visibility culling, since it is inherently four-dimensional. We present a conservative occlusion culling method based on factorizing the 4D visibility problem into horizontal and vertical components. The visibility of the two components is solved asymmetrically: the horizontal component is based on a parameterization of the ray space, and the visibility of the vertical component is solved by incrementally merging umbrae. The technique is designed so that the horizontal and vertical operations can be efficiently realized together by modern graphics hardware. Similar to image-based from-point methods, we use an occlusion map to encode visibility; however, the image-space occlusion map is in the ray space rather than in the primal space. Our results show that the culling time and the size of the computed potentially visible set depend on the size of the viewcell. For moderate viewcells, conservative occlusion culling of large urban scenes takes less than a second, and the size of the potentially visible set is only about two times larger than the size of the exact visible set.

Original languageEnglish
Pages (from-to)595-604
Number of pages10
JournalACM Transactions on Graphics
Issue number3
StatePublished - Jul 2003
EventACM SIGGRAPH 2003 - San Diego, CA, United States
Duration: 27 Jul 200331 Jul 2003


  • Dual space
  • Hardware acceleration
  • Line parameterization
  • Occlusion culling
  • PVS
  • Visibility


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