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DTSTAMP:20250110T023312Z
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:Technical Papers\n\nYusuke Tokuyoshi, Sho Ikeda, Paritosh Kulk
 arni, and Takahiro Harada (Advanced Micro Devices, Inc.)\n\nImportance sam
 pling using a light tree (i.e., a hierarchy of light clusters) has been wi
 dely used for many-light rendering. This technique samples a light source 
 by stochastically traversing the tree according to the importance of each 
 node. While this importance should be close to the illumination integral f
 or each node's light cluster, it is infeasible to compute the exact soluti
 on. Therefore, existing methods used a rough approximation (e.g., upper bo
 und), which results in significant Monte Carlo variance, especially for hi
 gh-frequency microfacet BRDFs at grazing angles. In this paper, we present
  a more accurate approximation of the importance based on spherical Gaussi
 ans (SGs). Our method represents a light cluster with an SG light for each
  node, and analytically approximates the product integral of the SG light 
 and a BRDF. Although high-quality SG lighting approximations have been stu
 died, they could not be used for the node importance due to violations of 
 an unbiased sampling constraint. To improve the sampling quality and satis
 fy the constraint for anisotropic microfacet BRDFs, we introduce a new hig
 h-quality SG lighting approximation by extending an NDF filtering method t
 hat has been used for specular antialiasing. For diffuse surfaces, we also
  present a simpler and more accurate SG lighting than the state-of-the-art
  SG approximation, satisfying the constraint. Using our method, we can eff
 iciently reduce the Monte Carlo variance for many-light scenes with modern
  physically plausible materials.\n\nRegistration Category: Full Access, Fu
 ll Access Supporter\n\nLanguage Format: English Language\n\nSession Chair:
  Seungyong Lee (POSTECH)
URL:https://asia.siggraph.org/2024/program/?id=papers_723&sess=sess131
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