Visibility sweeps for joint-hierarchical importance sampling of direct lighting for stochastic volume rendering

Physically-based light transport in heterogeneous volumetric data is computationally expensive because the rendering integral (particularly visibility) has to be stochastically solved. We present a visibility estimation method in concert with an importance-sampling technique for efficient and unbiased stochastic volume rendering. Our solution relies on a joint strategy, which involves the environmental illumination and visibility inside of the volume. A major contribution of our method is a fast sweeping-plane algorithm to progressively estimate partial occlusions at discrete locations, where we store the result using an octahedral representation. We then rely on a quadtree-based hierarchy to perform a joint importance sampling. Our technique is unbiased, requires little precomputation, is highly parallelizable, and is applicable to a various volume data sets, dynamic transfer functions, and changing environmental lighting.

@InProceedings { KEE15,
  author       = "Kroes, Thomas and Eisemann, Martin and Eisemann, Elmar",
  title        = "Visibility sweeps for joint-hierarchical importance sampling of direct lighting for stochastic volume
                  rendering",
  booktitle    = "Proc. of Graphics Interface (GI)",
  year         = "2015",
  publisher    = "Canadian Information Processing Society",
  url          = "http://graphics.tudelft.nl/Publications-new/2015/KEE15"
}