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BEGIN:VEVENT
DTSTAMP:20260817T171533Z
LOCATION:Hall B5 (2)\, B Block\, Level 5
DTSTART;TZID=Asia/Tokyo:20241205T130000
DTEND;TZID=Asia/Tokyo:20241205T131100
UID:siggraphasia_SIGGRAPH Asia 2024_sess131_papers_723@linklings.com
SUMMARY:Hierarchical Light Sampling with Accurate Spherical Gaussian Light
 ing
DESCRIPTION:Yusuke Tokuyoshi, Sho Ikeda, Paritosh Kulkarni, and Takahiro H
 arada (Advanced Micro Devices, Inc.)\n\nImportance sampling using a light 
 tree (i.e., a hierarchy of light clusters) has been widely used for many-l
 ight rendering. This technique samples a light source by stochastically tr
 aversing the tree according to the importance of each node. While this imp
 ortance should be close to the illumination integral for each node's light
  cluster, it is infeasible to compute the exact solution. Therefore, exist
 ing methods used a rough approximation (e.g., upper bound), which results 
 in significant Monte Carlo variance, especially for high-frequency microfa
 cet BRDFs at grazing angles. In this paper, we present a more accurate app
 roximation of the importance based on spherical Gaussians (SGs). Our metho
 d represents a light cluster with an SG light for each node, and analytica
 lly approximates the product integral of the SG light and a BRDF. Although
  high-quality SG lighting approximations have been studied, they could not
  be used for the node importance due to violations of an unbiased sampling
  constraint. To improve the sampling quality and satisfy the constraint fo
 r anisotropic microfacet BRDFs, we introduce a new high-quality SG lightin
 g approximation by extending an NDF filtering method that has been used fo
 r specular antialiasing. For diffuse surfaces, we also present a simpler a
 nd more accurate SG lighting than the state-of-the-art SG approximation, s
 atisfying the constraint. Using our method, we can efficiently reduce the 
 Monte Carlo variance for many-light scenes with modern physically plausibl
 e materials.\n\nRegistration Category: Full Access, Full Access Supporter\
 n\nLanguage Format: English Language\n\nSession Chair: Seungyong Lee (POST
 ECH)\n\n
URL:https://asia.siggraph.org/2024/program/?id=papers_723&sess=sess131
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