Ned Greene
Apple Computer
This talk will summarize the hierarchical visibility algorithm which was designed to efficiently render very complex three-dimensional scenes. The algorithm maintains hierarchical data structures in both object space and image space to enable finding visible geometry by logarithmic search. To render a scene, the algorithm traverses nodes in the object-space hierarchy (an octree) in front-to-back order, testing the bounding volumes of nodes for visibility and culling hidden nodes. Thus, only visible nodes and their children in the hierarchy are visited, and only primitives in visible nodes need to be rendered. This procedure culls most hidden geometry in densely occluded scenes, but some geometry will still overlap on the screen when primitives are projected. To cull remaining hidden geometry, we perform hierarchical culling in image space, using the image-space hierarchy to maintain visibility information about previously rendered geometry. The talk will include recent work on hierarchical polygon tiling using coverage masks. Some of this research was done in collaboration with Michael Kass and Gavin Miller.
Ned Greene is a member of the Advanced Technology Group at Apple Computer where he conducts research in computer graphics and animation. From 1980 to 1989 he was a member of the computer animation research group at the New York Institute of Technology. He holds a PhD in computer science from the University of California at Santa Cruz.