Title: iCheat: A Representation for Artistic Control of Cinematic Lighting
1iCheat A Representation for Artistic Control of
Cinematic Lighting
3
1
2
Juraj Obert
Jaroslav Krivánek
Fabio Pellacini
1
2
Daniel Sýkora
Sumanta Pattanaik
1
University of Central Florida
2
Czech Technical University in Prague
3
Dartmouth College
2Motivation
- 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
3Goal
- Simple artistic control of indirect illumination
4Existing 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
5Our Approach
- Holistic approach
- Direct control of the interaction between
- direct lighting
- materials
- geometry
6Lighting Design Pipeline
Real-time preview
Lighting design interface
Final rendering
7Lighting Design Interface
- Obert07
- 4D selection
- caster
- receiver
- Modification
- hue / sat / intensity
- falloff
Lighting design interface
8Lighting Design Pipeline
Real-time preview
Lighting design interface
Final rendering
9Real-Time Preview
- Direct-to-Indirect Transfer Hasan06
- Transfer matrix T
- direct on gather samples -gt indirect on view
samples - Performance / flexibility modifications
- Row-wise matrix multiply
- Screen space sub-sampling and interpolation
Real-time preview
10Lighting Design Pipeline
Real-time preview
Lighting design interface
Final rendering
11Encoding of Indirect Illumination Adjustments
- Key idea
- Discrete sampling in 4D
- Scale/offset modify the transport matrix T
12Example Edits Indirect Brightness
Sphere reflects more light into the environment
13Example editsColor bleeding
Blue wall bleeds more color on the cone
14Geometry Term Edits
- Modify the geometry term G(g,v)
- Linear w.r.t. direct illumination at gather
samples - Example effects
- Distance falloff modification, orientation-based
modification, etc.
15General Edits
- Non-linear w.r.t. direct illumination at gather
samples - s / o matrices valid for current direct
illumination - Example effects
- 4D gamma correction, 4D HSV correction, etc.
16Lighting Design Pipeline
Real-time preview
Lighting design interface
Final rendering
17Final rendering
- Applicable to any GI algorithm
- Our implementation
- irradiance caching Ward88
- radiance caching Krivánek05
- 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
18Final Rendering Example
Original
Design 1
Design 2
19Animation
- Edits designed per key-frame
- Interpolated for other frames
- Possible artifacts when previously occluded large
areas become suddenly visible
20Interpolation Example
Original
Original
Original
iCheat Keyframe
Interpolated frame
iCheat keyframe
21More Interpolation
Original
Original
Original
iCheat Keyframe
Interpolated frame
iCheat keyframe
22Video
23Conclusion
- 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
24Acknowledgements
- Vlasta Havran
- 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
25References
- 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.
16. - HAAN M., PELLACINI F., BALA K.
Direct-to-indirect transfer for cinematic
relighting. ACM Trans. Graph. (Proc. SIGGRAPH)
25, 3 (2006), 10891097. - KRIVÁNEK J., GAUTRON P., PATTANAIK S., BOUATOUCH
K. Radiance caching for efficient global
illumination computation. IEEE Transactions on
Visualization and Computer Graphics 11, 5
(September/October 2005). - KAWAI J. K., PAINTER J. S., COHEN M. F.
Radioptimization Goal based rendering. In
SIGGRAPH93 Proceedings (1993), pp. 147154. - OBERT J., KRIVÁNEK J., SÝKORA D., PATTANAIK S.
Interactive light transport editing for flexible
global illumination. ACM SIGGRAPH 2007 sketches
26References
- PELLACINI F., BATTAGLIA F., MORLEY R. K.,
FINKELSTEIN A. Lighting with paint. ACM Trans.
Graph. (Proc. SIGGRAPH) 26, 2 (2007). - PELLACINI F., VIDIMCE K., LEFOHN A., MOHR A.,
LEONE M., WARREN J. Lpics A hybrid
hardware-accelerated relighting engine for
computer cinematography. ACM Trans. Graph. (Proc.
SIGGRAPH) 24, 3 (2005), 464470. - RAGAN-KELLEY J., KILPATRICK C., SMITH B. W., EPPS
D., GREEN P., HERY C., DURAND F. The lightspeed
automatic interactive lighting preview system.
ACM Trans. Graph. (Proc. SIGGRAPH) 26, 3 (2007). - TABELLION E., LAMORLETTE A. An approximate
global illumination system for computer generated
films. ACM Trans. Graph. (Proc. SIGGRAPH) 23, 3
(2004), 469476. - WARD G. J., RUBINSTEIN F. M., CLEAR R. D. A ray
tracing solution for diffuse interreflection. In
SIGGRAPH88 Proceedings (1988), pp. 8592.