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 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 Overview

6. First attempt: Master project Abrupt discontinuities in the representation Confidence method  Smooth threshold on colors Temporal coherence

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

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 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 Our goals

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

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

12. Denotation 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 Ongoing work: expressive rendering for animation

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

14. Temporal Coherence 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 Ongoing work: expressive rendering for animation

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 ?