Journal of KIISE:Computing Practices and Letters (한국정보과학회논문지:컴퓨팅의 실제 및 레터)

Korean Institute of Information Scientists and Engineers (한국정보과학회)
권호 표지

Analysis of Harmonic Mean Distance Calculation in Global Illumination Algorithms

전역 조명 알고리즘에서의 조화 평균 거리 계산의 분석

  • 차득현 (서강대학교 컴퓨터공학과) ;
  • 임인성 (서강대학교 컴퓨터공학과)
  • Published : 2010.02.15
Download PDF
⟨ Previous Next ⟩

Abstract

In order to render global illumination realistically, we need to accurately compute the direct and indirect illumination that represents the light information incoming through complex light paths. In this process, the indirect illumination at given point is greatly affected by surrounding geometries. Harmonic mean distance is a mathematical tool which is often used as a metric indicating the distance from a surface point to its visible objects in 3D space, and plays a key role in such advanced global illumination algorithms as irradiance/radiance caching and ambient occlusion. In this paper, we analyze the accuracy of harmonic mean distance estimated against various environments in the final gathering and photon mapping methods. Based on the experimental results, we discuss our experiences and future directions that may help develop an effective harmonic mean distance computation method in the future.

전역 조명(global illumination) 효과를 사실적으로 렌더링하기 위해서는 복잡한 경로를 통해 입사하는 빛의 정보 해당하는 직접 조명 및 간접 조명을 정확하게 계산해주어야 한다. 이 과정에서 주어진 물체 표면 지점에 대해 계산되는 간접 조명 정보는 주변 환경의 기하적인 형태에 큰 영향을 받게 된다. 조화 평균 거리(harmonic mean distance)는 3차원 공간상에서 주어진 한 지점에서 보이는 물체들과의 거리를 나타내는 척도로 많이 사용되는 수학적 도구로서, 광휘 캐시(irradiance/radiance cache)나 환경 폐색(ambient occlusion) 등의 렌더링 효과를 생성하는데 주요하게 사용된다. 본 논문에서는 대표적인 고품질 전역 조명 렌더링 알고리즘인 최종 수집(final gathering) 방법 및 포톤 매핑(photon mapping) 기법을 통해 다양한 환경에서 계산되는 조화 평균 거리에 대한 근사값의 정확성에 대해 분석한다. 이러한 분석 결과를 기반으로 효과적인 조화 평균 거리 계산의 근사화 기법 개발에 있어서 고려해야 할 점들과 방향을 제시한다.

Keywords

References

  1. J. T. Kajiya, "The rendering equation," Journal of ACM Transactions on Graphics, vol.20, no.4, pp. 143-150, 1986.
  2. T. Whitted, "An improved illumination model for shaded display," In Proc. of ACM SIGGRAPH'79, 1979.
  3. R. L. Cook, T. Porter and L. Carpenter, "Distributed ray tracing," In Proc. of ACM SIGGRAPH'84, pp.137-145, 1984.
  4. C. M. Goral, K. E. Torrance, D. P. Greenberg and B. Battaile, "Modeling the interaction of light between diffuse surfaces," In Proc. of ACM SIGGRAPH' 84, pp.213-222, 1984.
  5. M. F. Cohen and D. P. Greenberg, "The hemicube: a radiosity solution for complex environments," In Proc. of ACM SIGGRAPH'85, pp.31-40, 1985.
  6. H. W. Jensen, "Importance driven path tracing using the photon map," In proc. of Sixth Eurographics Workshop on Rendering, pp.326-335, 1995.
  7. H. W. Jensen, "Global illumination using photon maps," In proc. of Seventh Eurographics Workshop on Rendering, pp.21-30, 1996.
  8. M. Reichert, "A two-pass radiosity method driven by lights and viewer position," Master's thesis, Cornell University, 1992.
  9. G. Ritschel, T. Grosch, M. H. Kim, H. -P. Seidel, C. Bacher and J. Kautz, "Imperfect shadow maps for efficient computation of indirect illumination," In Proc. of ACM SIGGRAPH Asia'08, no.129, 2008.
  10. R. Wang, R. Wang, K. Zhou, M. Pan and H. Bao, "An efficient GPU-based approach for interactive global illumination," Proc. of ACM SIGGRAPH'09, no.91, 2009.
  11. T. Ritschel, T. Engelhardt, T. Grosch, H.-P. Seidel, J. Kautz, C. Dachsbacher, "Micro-rendering for scalable, parallel final gathering," In Proc. of ACM SIGGRAPH Asia'09, no.132. 2009.
  12. T. Ritschel, T. Grosch, H.-P. Seidel, "Approximating dynamic global illumination in image space," In Proc. of the 2009 symposium on Interactive 3D graphics and games, pp.75-82, 2009.
  13. G. Ward and P. Heckbert, "Irradiance gradients," In Proc. of 3rd Eurographics Workshop on Ren dering, pp.85-98, 1992.
  14. J. Krivanek and P. Gautron, "Radiance caching for efficient global illumination computation," Journal of IEEE Transactions on Visualization and Computer Graphics, vol.11, no.5, pp.550-561, 2005. https://doi.org/10.1109/TVCG.2005.83
  15. R. L. Cook and K. E. Torrance, "A reflectance model for computer graphics," In Proc. of ACM SIGGRAPH'89, pp.307-316, 1981.
  16. S. Zhukov, A. Iones and G. Kronin, "An ambient light illumination model," In Proc. of Eurographics Workshop on Rendering, pp.45-56, 1998.
  17. R. Herzog, V. Havran, S. Kinuwaki, K. Myszkowski and H. -P. Seidel, "Global illumination using photon ray splatting," Journal of Computer Graphics Forum., vol.26, no.3, pp.503-512, 2007. https://doi.org/10.1111/j.1467-8659.2007.01073.x