Ishair: Importance sampling for hair scattering

We present an importance sampling method for the bidirectional scattering distribution function (bsdf) of hair. Our method is based on the multi-lobe hair scattering model presented by Sadeghi et al. . We reduce Noise by drawing samples from a distribution that approximates the bsdf well. Our algorithm is efficient and Easy to implement, since the sampling process requires only the evaluation of a few analytic functions, with no Significant memory overhead or need for precomputation. We tested our method in a research raytracer and a Production renderer based on micropolygon rasterization. We show significant improvements for rendering direct Illumination using multiple importance sampling and for rendering indirect illumination using path tracing. © 2012 The Author(s).