Sung-Eui Yoon, Brian Salomon, and Dinesh Manocha
Video: encoded with DivX (24 MB)
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Runtime System Diagram. In each frame the clusters visible in the previous frame are used as an occluder set. In Phases 1 and 2, the occluder set is refined and then rendered in to create a depth map in the z-buffer. Phase 3 tests bounding boxes of all the active clusters against this depth map using occlusion queries. Clusters passing the test are used as the occlusion set for the next frame. The clusters passing the test are refined and rendered in Phases 4 and 5.
This paper presents a novel algorithm combining view-dependent rendering and conservative occlusion culling for interactive display of complex environments. A vertex hierarchy of the entire scene is decomposed into a cluster hierarchy through a novel clustering and partitioning algorithm. The cluster hierarchy is then used for view-frustum and occlusion culling. Using hardware accelerated occlusion queries and frame-to-frame coherence, a potentially visible set of clusters is computed. An active vertex front and face list is computed from the visible clusters and rendered using vertex arrays. The integrated algorithm has been implemented on a Pentium 4 PC with a NVIDIA GeForce 4 graphics card and applied in two complex environments composed of millions of triangles. The resulting system can render these environments at interactive rates with little loss in image quality and minimal popping artifacts.
Occlusion culling in the power plant. The left image shows a first person view. The middle image shows a third person view with the bounding boxes of visible clusters shown in pink and the view frustum in white. The right image is from the same third person view with the bounding boxes of occluded clusters in yellow.
CB #3175, Department of Computer Science
University of North Carolina
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