expressive rendering for animation pascal barla artis-gravir / imag inria advisers : françois...

Expressive rendering for animation

Pascal Barla

ARTIS-GRAVIR / IMAG INRIA

Advisers : François Sillion & Joëlle Thollot

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

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

Plan Introduction First attempt : Master project

Overview Temporal coherence Results

Ongoing work : expressive rendering for animation Conclusion

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 renderedwith regions

Overview

First attempt: Master project

• Abrupt discontinuities in the representation

• Confidence method Smooth threshold on colors

Temporal coherence

First attempt: Master project

• 2 videos

• Remaining problems• color metric• temporal coherence

Results

Plan Introduction First attempt : Master project Ongoing work : expressive rendering for animation

Our goals Archeological applications System overview Denotation Composition Temporal coherence

Conclusion

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

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

System overview

• “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

Ongoing work: expressive rendering for animation

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

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

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 concatenationmakes a video cube

A frame is obtained by a cut through the cube

Ongoing work: expressive rendering for animation

Conclusion• Expressive rendering system for animation

• Image-space Post-processing, automatic simplification

• 2D+time Temporal coherence

• User-controlled• Video Cube operators

Work in progress…

Questions ?