2 ) makes rendering impractical with standard techniques: the highlights are missed by naive pixel sampling. Left inset: Our solution is based on the concept of a pixel normal distribution function (P-NDF), which can be highly complex. Right inset: Our method is accurate even in a moving-light sequence. Complex specular surfaces under sharp point lighting show a fascinating glinty appearance, but rendering it is an unsolved problem. Using Monte Carlo pixel sampling for this purpose is impractical: the energy is concentrated in tiny highlights that take up a minuscule fraction of the pixel. We instead compute an accurate solution using a completely different deterministic approach. Our method considers the true distribution of normals on a surface patch seen through a single pixel, which can be highly complex. We show how to evaluate this distribution efficiently, assuming a Gaussian pixel footprint and Gaussian intrinsic roughness. We also take advantage of hierarchical pruning of position-normal space to rapidly find texels that might contribute to a given normal distribution evaluation. Our results show complex, temporally varying glints from materials such as bumpy plastics, brushed and scratched metals, metallic paint and ocean waves.
The closest previous work to our approach, REF considers the actual, unsimplified NDF of a surface patch P seen through a single pixel.
Rendering glints on high-resolution normal-mapped specular surfaces
TOGS
Computer Science