I am a Tree: Embodiment Using Physically Based Animation Driven by Expressive Descriptors of Motion Caroline Larboulette, Sylvie Gibet EXPRESSION team, IRISA lab University of South Brittany MOCO 2016, Thessaloniki, Greece
Motivation How do motion qualities influence the evolution of a 3D simulated system ?
Captured Human Movement
Non-Anthropomorphic Entity 2
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Related Work • Control of a MSS using motion descriptors [Alaoui et al. 13]
• Dance with virtual body extensions [Bisig et al. 16] • Sonification of human full-body movement qualities [Kolykhalova et al. 16]
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Our System • Physically based system • Mass-Spring System: 5 particles + 9 springs • Leaves: 1 particle emitter for each branch • Rendering: • Trunk: static generalized cylinder • Branches: Hermite Splines + cylinders 4
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Motion Descriptors • • • •
CoM: distance from Center of Mass to Root joint Bounding Volume: volume of the bounding box Shape Directional: arc-like versus spoke-like Extensiveness: normalized sum of the distances between CoM and end effectors (hands, feet, shoulders, head)
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Motion Descriptors • Laban Effort Descriptors • Flow Effort: free versus bound • Time Effort: sudden versus sustained • Space Effort: direct versus indirect • Weight Effort: strong versus light • Equations can be found in A Review of Computable Expressive Descriptors of Human Motion, Larboulette and Gibet, MOCO 2015 6
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Tree Shape • Bending of the tree - CoM-Root Pcenter Mass-Spring System (3D)
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Tree Shape • Bending of the tree (CoM-Root Pcenter MSS) • Breathing of the tree - Volume of Bounding Box Spring restlengths
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Tree Shape • Bending of the tree (CoM-Root Pcenter MSS) • Breathing of the tree (BVol Spring L0) • Curvature (arc-like versus spoke-like) - Shape Directional m1.z values of Hermite Splines
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Tree Shape • Bending of the tree (CoM-Root Pcenter MSS) • Breathing of the tree (BVol Spring L0) • Curvature (Shape Directional m1.z Splines) • Fluidity (free versus bound) - Flow Effort Spring Stiffness and Damping 30000
Stressed
25000
Sad
20000
Neutral
15000
Happy
10000
Cool
5000 0
0
1000
2000
3000
10
4000
5000
6000
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Leaves • Time Effort (sudden versus sustained) vz : how fast leaves fall rate of particles emission: how fast leaves rise • Space Effort (direct versus indirect) vx & vy : How straight leaves fall
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Parameters Mapping • Colors • Extensiveness Hue • Weight Effort Brightness strong = dark ; light = bright
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Results
• All together ! • Placed on the arousal / valence graph, according to the expected values
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Arousal
Stressed
Sad
Happy
Aroused
Valence
Calm
Unpleasant/Pleasant
Cool
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluations • Baseline Experiment • 5 animations, 17 participants • Asked to qualify each video • Emotions were recognized • Valence / Arousal Perceptual Study • 30 videos: 3 movements x 5 emotions x 2 renderings • 31 participants • Valence and Arousal graded on a 1-7 Lickert scale
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluation: Happy
Expected Scores: Positive (valence > 4) Energetic (arousal > 4)
Valence Arousal 16
Character
Tree
All
5,366 5,258
4,258 5,731
4,812 5,495
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluation: Cool
Expected Scores: Positive (valence > 4) Lethargic (arousal < 4)
Valence Arousal 17
Character
Tree
All
4,28 3,796
3,978 4,28
4,129 4,038
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluation: Neutral
Expected Scores: Valence = 4 Arousal = 4
Valence Arousal 18
Character
Tree
All
4,71 3,645
3,86 3,763
4,285 3,704
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluation: Sad
Expected Scores: Negative (valence < 4) Lethargic (arousal < 4)
Valence Arousal 19
Character
Tree
All
3,602 2,312
3,29 2,946
3,446 2,629
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Evaluation: Stressed
Expected Scores: Negative (valence < 4) Energetic (arousal > 4)
Valence Arousal 20
Character
Tree
All
4,559 4,914
3,559 4,602
4,059 4,758
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Conclusions • Successfully coupled expressive motion to a simulated 3D system • Indirect mapping with higher level descriptors • Non-anthropomorphic physical system • Perceptual studies showed that emotions were transferred
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Conclusions • Need to investigate different systems • New physical model • New set of descriptors • New mapping • Turn our experiments into live performances
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Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Perspectives 1. Descriptors Sensitivity • Parts of the body used for computation • Time window and offset • Nature of the skeleton’s structure and size 2. Mapping Importance • Effect of each parameter • Normalisation of the descriptors wrt the simulation 23
Related Work - System/Descriptors - Mapping - Results/Evaluations - Conclusion/Perspectives
Perspectives 3. Structure of the Physical System • Anthropomorphic / Non-Anthropomorphic • Methodology: do partial evaluations • Watch the variation of a descriptor in real-time • Do mappings for unitary simulation (one object, one parameter at a time)
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Thank You ! ευχαριστώ !
Caroline Larboulette, Sylvie Gibet University of South Brittany / IRISA http://www-expression.irisa.fr/
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