“A Practical Stochastic Algorithm for Rendering Mirror-Like Flakes” by Atanasov and Koylazov

  • ©Asen Atanasov and Vladimir Koylazov



Entry Number: 67


    A Practical Stochastic Algorithm for Rendering Mirror-Like Flakes



    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.


    Idehy, H. 1999. Tracing ray differentials. In Proceedings of SIGGRAPH 99, ACM Press/Addison-Wesley Publishing Co. Google ScholarDigital 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.



    We thank Stephen Parker, Rossen Dimov, Yordan Madzhunkov, Simeon Balabanov, Kalina Panteleeva, Yavor Stoikov, Emanuele Lecchi, Christopher Nichols and Rhys Dippie.


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