Separable Subsurface Scattering

Information

• Publication Type: Journal Paper with Conference Talk
• Workgroup(s)/Project(s):
  • Modern Functional Analysis in Computer Graphics
• Date: June 2015
• Journal: Computer Graphics Forum
• Volume: 34
• Number: 6
• Location: Darmstadt
• Lecturer: Christian Freude
• ISSN: 1467-8659
• Event: Eurographics Symposium on Rendering (EGSR)
• Conference date: 23. June 2015 – 26. June 2015
• Pages: 188 – 197
• Keywords: separable, realtime rendering, subsurface scattering, filtering

Abstract

In this paper we propose two real-time models for simulating subsurface scattering for a large variety of translucent materials, which need under 0.5 milliseconds per frame to execute. This makes them a practical option for real-time production scenarios. Current state-of-the-art, real-time approaches simulate subsurface light transport by approximating the radially symmetric non-separable diffusion kernel with a sum of separable Gaussians, which requires multiple (up to twelve) 1D convolutions. In this work we relax the requirement of radial symmetry to approximate a 2D diffuse reflectance profile by a single separable kernel. We first show that low-rank approximations based on matrix factorization outperform previous approaches, but they still need several passes to get good results. To solve this, we present two different separable models: the first one yields a high-quality diffusion simulation, while the second one offers an attractive trade-off between physical accuracy and artistic control. Both allow rendering subsurface scattering using only two 1D convolutions, reducing both execution time and memory consumption, while delivering results comparable to techniques with higher cost. Using our importance-sampling and jittering strategies, only seven samples per pixel are required. Our methods can be implemented as simple post-processing steps without intrusive changes to existing rendering pipelines.

https://www.youtube.com/watch?v=P0Tkr4HaIVk

Additional Files and Images

Weblinks

• http://onlinelibrary.wiley.com/doi/10.1111/cgf.12529/abstract

BibTeX

@article{Jimenez_SSS_2015,
  title =      "Separable Subsurface Scattering",
  author =     "Jorge Jimenez and Karoly Zsolnai-Feh\'{e}r and Adrian Jarabo
               and Christian Freude and Thomas Auzinger and Xian-Chun Wu
               and Javier van der Pahlen and Michael Wimmer and Diego
               Gutierrez",
  year =       "2015",
  abstract =   "In this paper we propose two real-time models for simulating
               subsurface scattering for a large variety of translucent
               materials, which need under 0.5 milliseconds per frame to
               execute. This makes them a practical option for real-time
               production scenarios. Current state-of-the-art, real-time
               approaches simulate subsurface light transport by
               approximating the radially symmetric non-separable diffusion
               kernel with a sum of separable Gaussians, which requires
               multiple (up to twelve) 1D convolutions. In this work we
               relax the requirement of radial symmetry to approximate a 2D
               diffuse reflectance profile by a single separable kernel. We
               first show that low-rank approximations based on matrix
               factorization outperform previous approaches, but they still
               need several passes to get good results. To solve this, we
               present two different separable models: the first one yields
               a high-quality diffusion simulation, while the second one
               offers an attractive trade-off between physical accuracy and
               artistic control. Both allow rendering subsurface scattering
               using only two 1D convolutions, reducing both execution time
               and memory consumption, while delivering results comparable
               to techniques with higher cost. Using our
               importance-sampling and jittering strategies, only seven
               samples per pixel are required. Our methods can be
               implemented as simple post-processing steps without
               intrusive changes to existing rendering pipelines. 
               https://www.youtube.com/watch?v=P0Tkr4HaIVk",
  month =      jun,
  journal =    "Computer Graphics Forum",
  volume =     "34",
  number =     "6",
  issn =       "1467-8659",
  pages =      "188--197",
  keywords =   "separable, realtime rendering, subsurface scattering,
               filtering",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2015/Jimenez_SSS_2015/",
}