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iCheat: A Representation for Artistic Control of Cinematic Lighting

iCheat: A Representation for Artistic Control of Cinematic Lighting. 1. 3. 2. Juraj Obert. Jaroslav K řivánek. Fabio Pellacini. 2. 1. Daniel Sýkora. Sumanta Pattanaik. 1. University of Central Florida. 2. Czech Technical University in Prague. 3. Dartmouth College. Motivation.

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iCheat: A Representation for Artistic Control of Cinematic Lighting

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  1. iCheat: A Representation for Artistic Control of Cinematic Lighting 1 3 2 Juraj Obert Jaroslav Křivánek Fabio Pellacini 2 1 Daniel Sýkora Sumanta Pattanaik 1 University of Central Florida 2 Czech Technical University in Prague 3 Dartmouth College

  2. Motivation • Lighting crucial for film • Story telling, scene mood, emotions • Simple control more important than physical accuracy • Direct illumination: easy to control • Indirect illumination: hard to control Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  3. Goal • Simple artistic control of indirect illumination Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  4. Existing Approaches • Relighting engines [Pellacini05, Ragan-Kelley07, Hasan06] • Goal-based lighting design [Schoeneman93, Kawai93, Pellacini07] • Procedural modifications of shader code [Christensen06] • Platform-specific solutions [Tabellion04] – filter lights Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  5. Our Approach • “Holistic approach” • Direct control of the interaction between • direct lighting • materials • geometry Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  6. Scale/offset matrix Lighting Design Pipeline Real-time preview Lighting design interface Final rendering Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  7. Lighting Design Interface • [Obert07] • 4D selection • caster • receiver • Modification • hue / sat / intensity • falloff … Lighting design interface Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  8. Scale/offset matrix Lighting Design Pipeline Real-time preview Lighting design interface Final rendering Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  9. Real-Time Preview • Direct-to-Indirect Transfer [Hasan06] • Transfer matrix T • direct on gather samples -> indirect on view samples • Performance / flexibility modifications • Row-wise matrix multiply • Screen space sub-sampling and interpolation Real-time preview Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  10. Scale/offset matrix Lighting Design Pipeline Real-time preview Lighting design interface Final rendering Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  11. = + T ' ( v , g ) s ( v , g ) T ( v , g ) o ( v , g ) Scale/offset matrix Encoding of Indirect Illumination Adjustments • Key idea: • Discrete sampling in 4D • Scale/offset modify the transport matrix T Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  12. Example Edits: Indirect Brightness Sphere reflects more light into the environment Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  13. Example edits:Color bleeding Blue wall bleeds more color on the cone Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  14. Geometry Term Edits • Modify the geometry term G(g,v) • Linearw.r.t. direct illumination at gather samples • Example effects: • Distance falloff modification, orientation-based modification, etc. Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  15. General Edits • Non-linearw.r.t. direct illumination at gather samples • s / o matrices valid for current direct illumination • Example effects • 4D gamma correction, 4D HSV correction, etc. Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  16. Scale/offset matrix Lighting Design Pipeline Real-time preview Lighting design interface Final rendering Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  17. Final rendering • Applicable to any GI algorithm • Our implementation: • irradiance caching [Ward88] • radiance caching [Křivánek05] • Radiance of gather rays modified by the s / o matrices • 4D interpolation Final rendering 17 Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  18. Final Rendering Example Original Design 1 Design 2 Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  19. Animation • Edits designed per key-frame • Interpolated for other frames • Possible artifacts when previously occluded large areas become suddenly visible Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  20. Interpolation Example Original Original Original Interpolated frame iCheat Keyframe iCheat keyframe Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  21. More Interpolation Original Original Original Interpolated frame iCheat Keyframe iCheat keyframe Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  22. Video Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  23. Conclusion • Artistic control of indirect illumination • Simple representation of edits • Scale / offset factors for discretely sampled 4D transfer operator • Comprehensive, renderer-independent, efficient • Limitations • More bulky than shader edits • Possible artifacts due to discrete sampling Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  24. Acknowledgements • VlastaHavran • Golem ray tracer • Universal Production Partners (upp.cz) • Orion scene • Ministry of Education of Czech Republic • “Center for Computer Graphics” • National Science Foundation • CNS-070820, CCF-0746117 Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  25. References • CHRISTENSEN P., FONG J., LAUR D., BATALI D.: Ray tracing for the movie cars. In Proc. of IEEE Symposium on Interactive Ray Tracing (2006), pp. 1–6. • HAŠAN M., PELLACINI F., BALA K.: Direct-to-indirect transfer for cinematic relighting. ACM Trans. Graph. (Proc. SIGGRAPH) 25, 3 (2006), 1089–1097. • KŘIVÁNEK J., GAUTRON P., PATTANAIK S., BOUATOUCH K.: Radiance caching for efficient global illuminationcomputation. IEEE Transactions on Visualization and ComputerGraphics 11, 5 (September/October 2005). • KAWAI J. K., PAINTER J. S., COHEN M. F.: Radioptimization:Goal based rendering. In SIGGRAPH’93 Proceedings(1993), pp. 147–154. • OBERT J., KŘIVÁNEK J., SÝKORA D., PATTANAIK S.: Interactive light transport editing for flexible global illumination. ACM SIGGRAPH 2007 sketches Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

  26. References • PELLACINI F., BATTAGLIA F., MORLEY R. K.,FINKELSTEIN A.: Lighting with paint. ACM Trans. Graph.(Proc. SIGGRAPH) 26, 2 (2007). • PELLACINI F., VIDIMČE K., LEFOHN A., MOHR A.,LEONE M., WARREN J.: Lpics: A hybrid hardware-acceleratedrelighting engine for computer cinematography. ACM Trans.Graph. (Proc. SIGGRAPH) 24, 3 (2005), 464–470. • RAGAN-KELLEY J., KILPATRICK C., SMITHB. W., EPPS D., GREEN P., HERY C., DURAND F.: The lightspeedautomatic interactive lighting preview system. ACM Trans.Graph. (Proc. SIGGRAPH) 26, 3 (2007). • TABELLION E., LAMORLETTE A.: An approximateglobal illumination system for computer generated films. ACMTrans. Graph. (Proc. SIGGRAPH) 23, 3 (2004), 469–476. • WARD G. J., RUBINSTEIN F. M., CLEAR R. D.: Aray tracing solution for diffuse interreflection. In SIGGRAPH’88Proceedings (1988), pp. 85–92. Obert et al. iCheat: A Representation for Artistic Control of Cinematic Lighting

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