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Precomputed Radiance Transfer Field for Rendering Interreflections in Dynamic Scenes

Precomputed Radiance Transfer Field for Rendering Interreflections in Dynamic Scenes. Minhao Pan , Rui Wang , Xinguo Liu , Qunsheng Peng and Hujun Bao State Key Lab of CAD&CG, Zhejiang University, P.R. China 23 / 7 /2007. Related works. Traditional global illumination methods

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Precomputed Radiance Transfer Field for Rendering Interreflections in Dynamic Scenes

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  1. Precomputed Radiance Transfer Fieldfor Rendering Interreflections in Dynamic Scenes Minhao Pan, Rui Wang, Xinguo Liu, Qunsheng Peng and Hujun Bao State Key Lab of CAD&CG, Zhejiang University, P.R. China 23/7/2007

  2. Related works Traditionalglobal illumination methods Based on ray-trace or radiosity Realistic but slow Precomputed light transport Static scene —— PRT[Sloan, 2002] Shadow in dynamic Scene ——[Zhou, 2005] Interreflections in dynamic scene ——[Iwasaki, 2007] Precomputed Radiance Transfer Field

  3. Radiance Transfer Field Precomputed Radiance Transfer Field

  4. Radiance Transfer Field Precomputed Radiance Transfer Field

  5. Radiance Transfer FieldInterreflection Transfer Function (ITF) Precomputed Radiance Transfer Field

  6. Radiance Transfer FieldInterreflection Transfer Function (ITF) Environment Lighting [Sloan, 2002] Precomputed Radiance Transfer Field

  7. Radiance Transfer FieldInterreflection Transfer Function (ITF) Environment Lighting [Sloan, 2002] Precomputed Radiance Transfer Field

  8. Radiance Transfer FieldInterreflection Transfer Function (ITF) Local lighting Precomputed Radiance Transfer Field

  9. Radiance Transfer FieldProxy-based incidient light approximation Precomputed Radiance Transfer Field

  10. Radiance Transfer FieldProxy-based incidient light approximation The incident light to p Precomputed Radiance Transfer Field

  11. Radiance Transfer FieldProxy-based incidient light approximation Local lighting Precomputed Radiance Transfer Field

  12. Radiance Transfer FieldProxy-based incidient light approximation Local lighting Precomputed Radiance Transfer Field

  13. Radiance Transfer FieldProxy-based incidient light approximation Local lighting Precomputed Radiance Transfer Field

  14. Radiance Transfer FieldProxy-based incidient light approximation Local lighting Precomputed Radiance Transfer Field

  15. Radiance Transfer Field Precomputed Radiance Transfer Field

  16. Precomputation Compute radiance transfer on each vertex Compute radiance transfer on samples in field Compress the radiance transfer field Precomputed Radiance Transfer Field

  17. PrecomputationCompute radiance transfer on vertices Precomputed Radiance Transfer Field

  18. PrecomputationCompute radiance transfer on samples in field Precomputed Radiance Transfer Field

  19. PrecomputationCompression The raw RTF data is quite large 4th-order SH, 8 - 24 proxies, 16 concentric spheres with 1536(6×16×16) directions. ——192 ∼ 576MB CPCA (Clustered Principle Component Analysis) The compression ratio is about 40-50:1 Precomputed Radiance Transfer Field

  20. RenderingOverview A two-level scheme Bouncing Step accumulate interreflections between objects Precomputed Radiance Transfer Field

  21. RenderingOverview A two-level scheme Bouncing Step accumulate interreflections between objects Shading Step compute the final shadings on vertices. Precomputed Radiance Transfer Field

  22. RenderingBouncing Step Iterative bouncing strategy In one iteration: For proxy q in bunny 1. compute the interreflections from proxy qk 2. sum all interreflections from other proxies Precomputed Radiance Transfer Field

  23. RenderingShading Step One pass. For each vertex: 1. compute the illumination from proxy qk 2. sum all illumination from proxies 3. standard PRT process Precomputed Radiance Transfer Field

  24. RenderingCaching strategies Caching RTF samples Store incident light at samples. Caching RTF eigens By using CPCA, we can store the product of eigens and the incident light of proxies. ——hit rate > 95% and reduce the cost > 90% Precomputed Radiance Transfer Field

  25. ResultsComparison Our approach Reference Precomputed Radiance Transfer Field

  26. Results A PC with Intel Core 2 Duo 1.8GHz, 2G RAM and a nVidia 7800 graphics card. Precomputed Radiance Transfer Field

  27. Conclusion and future work Contributions: 1. Radiance transfer field 2. A proxy-based approximation method for precomputed RTF 3. An efficient interreflection rendering algorithm using precomputed RTF There are also some limitations. 1. only handle low-frequency interreflections and illumination. 2. only limited to rigid objects. Precomputed Radiance Transfer Field

  28. Thank you!

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