Ambient Obscurance Baking on the GPU

Peter-Pike Sloan
NVIDIA / Activision
 
Jason Tranchida
Bungie
 
Hao Chen
Bungie
 
Ladislav Kavan
University of Pennsylvania
 


Ambient Obscurance (left) and a final frame in a game (right). Our method supports instanced trees and shrubs and the gun lighting changes as the character moves thanks to our new dynamic Ambient Obscurance model. c Bungie


Abstract

Ambient Occlusion and Ambient Obscurance are coarse approximations to global illumination from ambient lighting, commonly used in film and games. This paper describes a system that computes Ambient Obscurance over the vertices of complex polygon meshes. Novel contributions include pre-processing necessary for "triangle soup" scene representations to minimize artifacts, a compact model for different classes of instanced decorator objects such as trees and shrubs, a compact model for pre-computed visibility to be used on dynamically placed objetcs, and an approximation to model the occlusion of small decorator objects when ray tracing.


Publication

Peter-Pike Sloan, Jason Tranchida, Hao Chen, Ladislav Kavan. Ambient Obscurance Baking on the GPU. ACM SIGGRAPH Asia Technical Briefs, 2013.  

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Acknowledgements

Keith Morely and Dave McAllister on the OptiX team at NVIDIA helped considerably. We thank the anonymous reviewers for their feedback.