Parallel Occlusion Culling for Interactive Walkthroughs using Multiple GPUs

by Naga Govindaraju, Avneesh Sud, Sung-Eui Yoon and Dinesh Manocha.

SWITCH System Architecture: Each color represents a separate GPU. Note that GPU1 and GPU2 switch their roles each frame with one performing hardware culling and other rendering occluders. GPU3 is used as a display client.

We present a new parallel occlusion culling algorithm for interactive display of large environments. It uses a cluster of three graphics processing units (GPUs) to compute an occlusion representation, cull away occluded objects and render the visible primitives. Moreover, our parallel architecture reverses the role of two of the GPUs between successive frames to lower the communication overhead. We have combined the occlusion culling algorithm with pre-computed levels-of-detail and use it for interactive display of geometric datasets. The resulting system has been implemented and applied to large environments composed of tens of millions of primitives. In practice, it is able to render such models at interactive rates with little loss in image fidelity. The performance of the overall occlusion culling algorithm is based on the graphics hardware computational power growth curve which has recently outperformed the Moore's Law for general CPU power growth.

The DoubleEagle Tanker: This 4 gigabyte environment consists of more than 82 million triangles and 127 thousand objects. Our algorithm can render it 10-20 frames per second on a cluster of 3 PCs. Coal-Fired Power plant: This 1.7 gigabyte environment consists of over 13 million triangles and 1200 objects. SWITCH can display it 10-20 frames per second at less than 10 pixels of error on a cluster of 3 PCs.


Parallel Occlusion Culling for Interactive Walkthroughs using Multiple GPUs UNC Computer Science Technical Report TR02-027, 2002.

Interactive Visibility Culling in Complex Environments using Occlusion-Switches in ACM SIGGRAPH Symposium on Interactive 3D Graphics, 2003.

Videos/ Contains Videos demonstrating the SWITCH's interactive display.

UNC Walkthru Group

CB #3175, Department of Computer Science
University of North Carolina
Chapel Hill, NC 27599-3175