O07: Fast Indirect Lighting Approximations using the Representative Candidate Line Space

Keul,K., Koß,T., Müller,S.

We propose a novel approach for using directional Line Space information in calculation of indirect illumination. Typically, the Line Space is build on top of regular recursive grids and contains visibility information which is used to perform an efficient empty space skipping during traversal. In our method we extend the stored information by precomputed representative candidates, which are based on the Line Space shafts and serve as an approximation of the actual scene geometry. By using these candidates it is not necessary to compute any intersection tests and therefore the traversal is accelerated. However, the candidate approximation leads to visible artifacts. We therefore present a technique that significantly reduces these artifacts by extrapolation of the actual surface and demonstrate that the artifacts are nearly not perceivable in the application of indirect illumination. Moreover we adapt the Line Space to other data structures like bounding volume hierarchies (BVHs) which further increases the performance in ray tracing. Compared to the pure data structures we achieve significantly better performance with nearly no drawback in quality of indirect lighting.