“Bidirectional Path Tracing Using Backward Stochastic Light Culling”

  • ©Yusuke Tokuyoshi and Takahiro Harada

  • ©Yusuke Tokuyoshi and Takahiro Harada

  • ©Yusuke Tokuyoshi and Takahiro Harada

Conference:


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:


    T. Davidovič, J. Křivánek, M. Hašan, and P. Slusallek. 2014. Progressive Light Transport Simulation on the GPU: Survey and Improvements. ACM Trans. Graph. 33, 3, Article 29 (2014), 19 pages. Google ScholarDigital Library
    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
    E. Veach and L. J. Guibas. 1995. Optimally Combining Sampling Techniques for Monte Carlo Rendering. In SIGGRAPH ’95. 419–428. Google ScholarDigital Library
    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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