Expressive rendering for animation

1. Expressive rendering for animation Pascal Barla ARTIS-GRAVIR / IMAG INRIA Advisers : François Sillion & Joëlle Thollot

2. Plan • Introduction • First attempts : Master project • Ongoing work : expressive rendering for animation • Conclusion

3. Introduction • PR's aim : optical fidelity • Other aims : • preliminary work (i.e architecture) • artistic sensibility (i.e paintings & drawings) • representation hypothesis (i.e archeology) • Computer graphics need new representations A sketch of a stadium

4. Plan • Introduction • First attempt : Master project • Overview • Temporal coherence • Results • Ongoing work : expressive rendering for animation • Conclusion

5. First attempt: Master project Overview • Following the Dynamic Canvas • Interactive or real-time • But focus on colors • Image-space approach • Color regions extraction • Automatic simplification A simple cube rendered with regions

6. First attempt: Master project Temporalcoherence • Abrupt discontinuities in the representation • Confidence method • Smooth threshold on colors

7. First attempt: Master project Results • 2 videos • Remaining problems • color metric • temporal coherence

8. Plan • Introduction • First attempt : Master project • Ongoing work : expressive rendering for animation • Our goals • Archeological applications • System overview • Denotation • Composition • Temporal coherence • Conclusion

9. Ongoing work: expressive rendering for animation Our goals • Rendering of an animated sequence • knowledge of all events • User control • off-line manipulations vs interactive walkthroughs • System = low-level toolbox • high-level approach left to the user

10. Archeological applications Ongoing work: expressive rendering for animation • Traditionnal illustration = watercolor + lines • Watercolor animations • precomputed animations • qualitative archeological movies An illustration by J.C. Golvin

11. Systemoverview Ongoing work: expressive rendering for animation • “Pipeline plugin“ • behind a classic pipeline • works with G-Buffers [Saito90] • Main phases : denotation & composition [Willats97] Classic Pipeline Our System Two G-Buffers examples : color & depth

12. Denotation Ongoing work: expressive rendering for animation • Picture primitives • points, lines and regions • Primitives extraction • human perception models • Primitives generation • i.e brush strokes The perceptually uniform L*a*b* color space

13. Composition Ongoing work: expressive rendering for animation • Combine extracted & generated primitives • Render with 2D techniques • 2D Combinations <=> 3D shaders • Watercolor issues: plasma fractals A simple plasma fractal rendering

14. TemporalCoherence Ongoing work: expressive rendering for animation • Sudden inconsistencies (poppings & flickerings) • Our approach • video cube = adding a time axis • frame = cut into the cube along the time axis • 3D primitives = temporal coherence • Low-level operators • Contract/expand • Smoothing • Control points • … in space and/or time The frames concatenation makes a video cube A frame is obtained by a cut through the cube

15. Conclusion • Expressive rendering system for animation • Image-space • Post-processing, automatic simplification • 2D+time • Temporal coherence • User-controlled • Video Cube operators Work in progress…

16. Questions ?