Asen Atanasov
Vladimir Koylazov
ABSTRACT
Materials, such as snow, sand, metallic paints, rough plastics, and metals, often exhibit small-scale phenomena observed as bright sparkling or glittering surface features. These features become more pronounced under narrow-angle illumination and vary based on the orientation of the surface with respect to the viewer and light sources. Microfacet-based surface models, composed of a large finite number of microscopic mirror-like flakes, can mimic this effect. An associated microfacet BRDF and a memory-efficient stochastic algorithm are explored in [Jakob et al. 2014]. We present a new stochastic algorithm that inherits the good properties of the original algorithm, but does not require any precomputation; implements optimal importance sampling which is extended to efficiently sample wide and heavy-tailed microfacet distributions (i.e. GGX), and offers better overall performance. In addition, a triplanar mapping technique is employed to handle geometry without texture coordinates. The algorithm is both practical and easier to implement.
Supplemental Material
Available for Download
Supplemental files.
- Idehy, H. 1999. Tracing ray differentials. In Proceedings of SIGGRAPH 99, ACM Press/Addison-Wesley Publishing Co. Google Scholar
Digital Library
- Jakob, W., Haan, M., Yan, L.-Q., Lawrence, J., Ramamoorthi, R., and Marschner, S. 2014. Discrete stochastic microfacet models. ACM Transactions on Graphics (Proceedings of SIGGRAPH 2014) 33, 4. Google ScholarDigital Library
- Walter, B., Marschner, S., and Torrance, K. 2007. Microfacet models for refraction through rough surafaces. In Proceedings of the 18th Eurographics Conference on Rendering Techniques, 195--206. Google ScholarDigital Library
Index Terms
- A practical stochastic algorithm for rendering mirror-like flakes
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