“Bidirectional Path Tracing Using Backward Stochastic Light Culling”

  • ©Yusuke Tokuyoshi and Takahiro Harada

  • ©Yusuke Tokuyoshi and Takahiro Harada

  • ©Yusuke Tokuyoshi and Takahiro Harada

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Entry Number: 72

Title:

    Bidirectional Path Tracing Using Backward Stochastic Light Culling

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Abstract:


    Bidirectional path tracing (BPT) produces noticeable variance for specular-diffuse-specular reflections even if they are not perfectly specular. This is because sampling of the connection between a light vertex and eye vertex does not take bidirectional reflectance distribution functions (BRDFs) into account. This paper presents a novel unbiased sampling method referred to as backward stochastic light culling which addresses the problem of specular-diffuse-glossy reflections. Our method efficiently performs Russian roulette for many light vertices according to the glossy BRDF at a given eye vertex using a hierarchical culling algorithm. We combine our method with light vertex cache-based BPT using multiple importance sampling to significantly reduce variance when rendering caustics reflected on highly glossy surfaces.

References:


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    Y. Tokuyoshi and T. Harada. 2017. Stochastic Light Culling for VPLs on GGX Micro-surfaces. Comput. Graph. Forum 36, 4 (2017), 55–63. Google ScholarDigital Library
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    B. Walter, S. Fernandez, A. Arbree, K. Bala, M. Donikian, and D. P. Greenberg. 2005. Lightcuts: A Scalable Approach to Illumination. ACM Trans. Graph. 24, 3 (2005), 1098–1107.

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