Approximate Bias Compensation for Rendering Scenes with Heterogeneous Participating Media

Thomas Engelhardt, Jan Novák, Thorsten-W. Schmidt, and Carsten Dachsbacher

Computer Graphics Forum (Proceedings of Pacific Graphics 2012), vol. 31, no. 7

Our approximate bias compensation can be used in complex environments to recover the energy loss due to clamping the contribution of VPLs. In the Crytek Sponza the clamped volumetric and surface illumination was rendered in 39 minutes (using 118k VPLs), while the missing energy was recovered using a two-bounce ABC in only 13 minutes.

abstract

We present the rasterized bounding volume hierarchy (RBVH), a compact data structure that accelerates approximate ray casting of complex meshes and provides adjustable level of detail. During construction, we identify subtrees of BVHs containing surfaces that can be represented by height fields. For these subtrees the conventional ray-surface intersection, which possibly involves a large number of triangles, is replaced by a simple ray marching procedure to find the intersection with the surface. We describe GPU algorithms for construction, ray casting, and data querying of the RBVH that achieve comparable or higher performance than state of the art acceleration structures for triangle meshes. Moreover, RBVHs provide an inherent surface parameterization for storing data on the surfaces and natively handle triangle and point-based surface representations. We also show that RBVHs support adaptive level-of-detail and can be combined with traditional BVHs to handle complex scenes.

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bibtex

@article{Engelhardt2012ABC, 
    author    = {Thomas Engelhardt and Jan Nov\'{a}k and Thorsten-W. Schmidt and Carsten Dachsbacher}, 
    title     = {Approximate Bias Compensation for Rendering Scenes with Heterogeneous Participating Media}, 
    journal   = {Computer Graphics Forum (Proceedings of Pacific Graphics 2012)}, 
    volume    = {31}, 
    number    = {7}, 
    year      = {2012}, 
    pages     = {2145--2154}, 
}