Download - Pierre Bénard Ph.D. defense, 2011/07/07
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Pierre Bénard Supervised by François Sillion & Joëlle Thollot
07/07/2011
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• Expressive rendering
An alternative to photorealism
Tools for visual communication
• Interactive techniques
Direct user feedback
Dynamic visualization, video games…
[Herz98]
[GTDS04]
[CAS+97]
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Okami Okami
Prince of Persia Prince of Persia
Team Forteress 2 Team Forteress 2
Jet Set Radio
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Texture painting
McGuire et al., Stylized Rendering in Games, SIGGRAPH 2010 Course
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McGuire et al., Stylized Rendering in Games, SIGGRAPH 2010 Course
Improved Sobel filter
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McGuire et al., Stylized Rendering in Games, SIGGRAPH 2010 Course
Final compositing (textures + edges + fog)
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McGuire et al., Stylized Rendering in Games, SIGGRAPH 2010 Course
Original Stylized
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Temporal incoherencies
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© Patrick Martin
Spatial Spatial
Attributes Attributes
Primitives Primitives Marks Marks 3D scene 2D image
perspective projection
2D lines and regions
color, shading, curvature…
pastel strokes
[Willats 97, Durand 02]
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• Marks medium and pattern
Marks Marks
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vs. Temporal continuity
« Il p
leut b
ergère », Jérém
y Dep
uyd
t (200
5)
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Random changes Popping / Flickering
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Static marks Shower-door effect
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vs. Coherent Motion
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Texture mapping 3D appearance
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vs. Flatness
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Motion coherence
Temporal continuity
Flatness
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Conflicting goals compromise
Motion coherence
Temporal continuity
Flatness
Texture mapping
Static marks Random changes
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Ideal solution
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• REGIONS
Dynamic Solid Textures P. Bénard, A. Bousseau, J. Thollot, I3D 2009
NPR Gabor Noise
P. Bénard, A. Lagae, P. Vangorp, S. Lefebvre, G. Drettakis, J. Thollot, EGSR 2010
• LINES
Self-Similar Line Artmap P. Bénard, F. Cole, A. Golovinskiy, A. Finkelstein, NPAR 2010
Active Strokes work in progress
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Temporally coherent bricks for stylized animations
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Perceptual Evaluation
Mapping Policies
Self Similar Line Artmap
Snakes-based Tracking and Parameterization
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Perceptual Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
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• Distribution of marks
• Textures
[VBTS07] [VBTS07]
[CTP+03] [CTP+03]
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• Distribution of marks
Few-marks
Many-marks
• Textures
[VBTS07] [VBTS07]
[CTP+03] [CTP+03]
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Few-marks [Mei96,Dan99,HE04,
VBTS07,LSF10]
Motion coherence
Temporal continuity
Flatness
[Meie
r96]
3D distribution of anchor points
2D stroke texture
Painterly rendering
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[VBTS07]
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Good compromise: 2D strokes vs. 3D motion
Clutter / holes
Popping / flickering
[Meier96] [Meier96]
or
[LSF10] [LSF10]
[HE04] [HE04]
[Daniels99]
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Many-marks [KC05,BKTS06]
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Motion coherence
Temporal continuity
Flatness
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Bridge the gap between texture and marks
Strong 2D appearance
Local motion and/or popping
Specific patterns (canvas fiber, watercolor pigments)
[KC05] [KC05]
[BKTS06]
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• Distribution of marks
• Textures
In image space: local or global
In objet space
[VBTS07] [VBTS07]
[CTP+03] [CTP+03]
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Local image space [BNTS07]
[BNTS07]
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Motion coherence
Temporal continuity
Flatness
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Strong 2D appearance
Regeneration artifacts
Post-production
[BNTS07]
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Global image space [CTP+03,CDH06,
BSM+07]
+ +
[CTP+03]
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Motion coherence
Temporal continuity
Flatness
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Strong 2D appearance
Infinite zoom mechanism
3D motion approximated sliding
[CDH+06] [CDH+06]
[BSM+06] [BSM+06]
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Object space [KLK+00,PHWF01,FMS01]
[PHWF01]
“Tonal Artmaps” 31
Motion coherence
Temporal continuity
Flatness
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Exact motion
MIP-mapping
Perspective distortion
Limited styles [FMS01]
[KLK+00]
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Local image space
Motion coherence
Temporal continuity
Flatness
Global image space
Motion coherence
Temporal continuity
Flatness
Object space
Motion coherence
Temporal continuity
Flatness
Few-marks
Motion coherence
Temporal continuity
Flatness
Many-marks
Motion coherence
Temporal continuity
Flatness
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Perceptual Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
Motion coherence
Temporal continuity
Flatness
Dynamic Solid Textures
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• Real-time texture-based approach
• Accurate 3D motion object space approach
• Infinite zoom Dynamic Canvas [CTP+03]
• Easy parameterization solid textures
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P. Bénard, A. Bousseau, J. Thollot, Dynamic Solid Textures for Real-Time Coherent Stylization. I3D 2009
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• Texture “Fractalization”
1 solid texture : 4 octaves
octave 2 octave 1 octave 3 octave 4 weighted sum
freq. x2 freq. x2 freq. x2
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• Zoom cycle
octave 2 octave 1 octave 3 octave 4 weighted sum
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• One solid texture + 3D coordinates
• Procedural textures [Per85, Ola05]
or synthesized from 2D exemplars [KFCO+07]
• Ogre3D rendering engine
Additional cost: 10% compared to Gouraud shading
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Homogeneity
Dynamic Solid Textures Standard 3D textures
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Shot in Ogre3D
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• Trade-off: Medium fidelity vs. Temporal continuity
• Linear blending new frequencies contrast loss
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Statistical Analysis
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular patterns
Irregular patterns
Cross- hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns Irregular patterns
Cross- hatching
S1
S2
P. Bénard, J. Thollot, F. Sillion, Quality Assessment of Fractalized NPR Textures. APGV 2009
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Perceptual Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
Motion coherence
Temporal continuity
Flatness
NPR Gabor Noise
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P. Bénard, A. Lagae, P. Vangorp, S. Lefebvre, G. Drettakis, J. Thollot, A Dynamic Noise Primitive for Coherent Stylization. EGSR 2010
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• Sparse convolution [Lewis 84,89]
• Spot Noise [van Wijk 91]
• Gabor Noise [LLDD09]
Offers significant spectral control
Support anisotropy
Our solution: NPR Gabor Noise
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• Definition
Sum of randomly positioned and weighted kernels
Gabor kernel
noise
random positions and weights
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anisotropic isotropic 𝐺 𝐾, 𝑎 × cos(𝐹0, 𝜔0)
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• Flatness
Noise parameters in image space
Evaluation in image space
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• Flatness
• Coherent motion
Point distribution on the surface of the 3D model
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• Flatness
• Coherent motion
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• Flatness
• Coherent motion
• Temporal continuity
Smooth LOD mechanism
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• Sample 3D triangles (GPU)
2D Poisson distribution with constant screen space density
Far • small screen area • less points
Close • large screen area • more points
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• Generate 2D point sprites
Point distribution Texture sprites
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• Blending scheme using statistical properties
Reduce popping
Preserve noise appearance
Far Close
visibility = 0 visibility = 1
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• Interactive scheme: remaining popping
“Procedural” approach
Slower, but should avoid popping
Useful for high quality offline rendering
• Gabor kernel
Temporally coherent spot noise
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Perceptual Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
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• Evaluate success of various solutions according to:
Motion
coherence Temporal continuity
Flatness
P. Bénard, A. Lagae, P. Vangorp, S. Lefebvre, G. Drettakis, J. Thollot, A Dynamic Noise Primitive for Coherent Stylization. EGSR 2010
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• Methodology
15 naïve subjects, ~ 20-30 minutes
• Ranking tasks “Rank the images/videos according to … ”
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Extreme cases
Local image space Global image space Object space
Many-marks
Adv D2D DST
nprGN SD TM
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Adv D2D DST
nprGN SD TM
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• Image space methods more flat for simple scene
• Many 3D cues flatness hard to perceive in complex scene
Flatness
Coherent motion
Temporal continuity
Pleasantness
Shower Door
Texture Mapping
Object space
Local image space
Global image space
Many-marks /
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• Object space methods more coherent
Flatness Coherent motion
Temporal continuity
Pleasantness
Shower Door
Texture Mapping
Object space
Local image space /
Global image space /
Many-marks / /
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• High variance
• Advection and NPR Gabor Noise produce more changes: organic motion
Flatness Coherent motion
Temporal continuity
Pleasantness
Shower Door
Texture Mapping
Object space
Local image space /
Global image space / /
Many-marks / / /
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• Object space approaches more pleasant
• Strong correlation with “motion coherence”
most important criteria to preserve
Flatness Coherent motion
Temporal continuity
Pleasantness
Shower Door
Texture Mapping
Object space
Local image space / /
Global image space / /
Many-marks / / / /
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• First formal evaluation
• Intrinsic limitations
Hatching
3D scenes
Naïve users
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• Two new solutions
Object space: Dynamic Solid Texture
Many-marks: NPR Gabor Noise
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Motion coherence
Temporal continuity
Flatness
NPR Gabor Noise
Motion coherence
Temporal continuity
Flatness
Dynamic Solid Textures
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• Simulation of brush strokes
Parameterization
0
l
Brush path
Line texture
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
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• Stretching
• Tiling
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• Stretching Temporally coherent
Stretch or compress the texture
• Tiling
Motion coherence
Temporal continuity
Flatness
Stretching
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• Stretching Temporally coherent
Stretch or compress the texture
• Tiling Preserve the texture characteristics
Incoherent sliding
• Fading / Artmap
Motion coherence
Temporal continuity
Flatness
Tiling
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• Stretching Temporally coherent
Stretch or compress the texture
• Tiling Preserve the texture characteristics
Incoherent sliding
• Fading / Artmaps No sliding
Blending artifacts Motion
coherence Temporal continuity
Flatness
Fading
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes Motion coherence
Temporal continuity
Flatness
SLAM
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P. Bénard, F. Cole, A. Golovinskiy, A. Finkelstein Self-Similar Texture for Coherent Line Stylization. NPAR 2010
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Lmax / 2
Lmax
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1) Density 2) Smooth variation
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3) Self-Similarity
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3) Self-Similarity
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• Parametric texture synthesis [PS00]
• Property: (empirical observation, no formal proof)
small change in noise seed small change in output texture [PS00] Portilla and Simoncelli,
A Parametric Texture Model based on Joint Statistics of Complex Wavelet Coefficients, 2000
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Exemplar
Synthesized Texture
White Noise Seed
[PS00]
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=
Wsource Wf
Seed Pyramid
Wf
[WfWf]
0.5
1
α Wf + (1-α) [WfWf]
Lmax
Lmax
Lmax / 2
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Synthesized textures Examples
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• Input
Silhouettes
Suggestive contours
Apparent ridges
• Arc-length artifacts
Coherent parameterization
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Previous Work
Dynamic Solid Textures
NPR Gabor Noise
Evaluation
Mapping Policies
Self Similar Line Artmap
Active Strokes
Work in progress in collaboration with C. Lu, F. Cole and A. Finkelstein 98
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• Flatness
Remain linear in screen-space
• Motion coherence
Evolve according to the motion of the objet
• Temporal continuity
Adapt to the topological events
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Coherent Stylized Silhouettes, Kalnins et al., SIGGRAPH 2003
Optimization between 2D and 3D
Multiple brush strokes per line
Dependent on the input connectivity
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Kalnins et al., Coherent Stylized Silhouettes, SIGGRAPH 2003
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Snakes
Snakes
3D scene
Lines extraction
Lines extraction
Feature samples
Line drawing
Brush Paths
Brush Paths
Parameterization Parameterization
Stylization Stylization Cleaning Vectorization
Cleaning Vectorization
Tracking Tracking
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Feature samples
Line drawing
• Position • Local tangent • Velocity
Snakes
Snakes
3D scene
Lines extraction
Lines extraction
Feature samples
Line drawing
Brush Paths
Brush Paths
Parameterization Parameterization
Stylization Stylization Cleaning Vectorization
Cleaning Vectorization
Tracking Tracking
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3D scene
Lines extraction
Lines extraction
Feature samples
Line drawing
Snakes
Snakes
Brush Paths
Brush Paths
Parameterization Parameterization
Stylization Stylization Cleaning Vectorization
Cleaning Vectorization
Tracking Tracking
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• Polylines • In image space • Persistent
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• Advection
• Relaxation
105 Frame f Frame f+1
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• Advection
• Relaxation
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3D scene
Lines extraction
Lines extraction
Feature samples
Line drawing
Snakes
Snakes
Brush Paths
Brush Paths
Parameterization Parameterization
Stylization Stylization Cleaning Vectorization
Cleaning Vectorization
Tracking Tracking
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• Linear screen space parameterization
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• Segments fitting
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• Arcs fitting
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Robustness toward noise / outliers
Temporal smoothing
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Input samples Active strokes
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• 4 new bricks for time coherent stylization
Dynamic Solid Textures
NPR Gabor Noise
Self-Similar Line Artmap
Active Strokes
• Formal evaluation
Formulation into 3 goals
2 perceptual studies
1 objective quality metric
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• 2D Animation
Ongoing work with Antoine Boellinger (Master 1)
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• 2D Animation
Ongoing work with Antoine Boellinger (Master 1)
• Evaluation & Objective metrics
Optical flow analysis
• Stylization by optimization
Versatile system to explore the space of trade-offs
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• Simple
• Strong motion coherence and temporal continuity
• More suitable for unstructured patterns
• Real-time animation
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• Input: pairs of 2D texture
• Definition: texture distortion = visual dissimilarity between original and transformed textures
• Goal: define a quantitative metric of this distortion
original transformed
P. Bénard, J. Thollot, F. Sillion, Quality Assessment of Fractalized NPR Textures. APGV 2009
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• Procedure:
User study ranking of texture pairs according to their distortion
Statistical analysis scale of perceived quality
Correlation investigation objective metric
• Restrictions:
No texture mapping
Static images
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• Ordinal scale
S1
S2
Statistical Analysis
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• Thurstone’s law of comparative judgment [Tor58]
Statistical Analysis
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular
patterns
Irregular
patterns
Cross-
hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns
Irregular
patterns
Cross-
hatching
S1
S2
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-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns Irregular patterns
Cross- hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular patterns
Irregular patterns
Cross- hatching
S1
S2
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Statistical Analysis
S1
S2
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular patterns
Irregular patterns
Cross- hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns Irregular patterns
Cross- hatching
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Overall contrast of patterns Feature shapes
Statistical Analysis
S1
S2
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular patterns
Irregular patterns
Cross- hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns
Irregular
patterns
Cross-
hatching
Paper Noise Paint Pigments
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Overall contrast of patterns
Feature shapes
Statistical Analysis
S1
S2
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular
patterns
Irregular
patterns
Cross-
hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns
Irregular
patterns
Cross-
hatching
Irregular patterns Cross-hatching Dots Hatching
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• Gray level co-occurrence matrix (GLCM) [HSD73]
Texture descriptor [TJ93]
Local image property
Match certain levels of human perception [JGSF76]
Linked to density and pattern coherence criteria
Parameters selection
• Average Co-occurrence Error [CRT01]
High correlation with the perceptual interval scale (Person’s correlation: 0.953 for S1 and 0.836 for S2 )
Correlation with Objective Metrics
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ACE relevant estimator of the distortion
S1
S2
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0
Grid Dots Hatching Paper Noise Paint Pigments Regular patterns
Irregular patterns
Cross- hatching
-1.5
Z-Scores
-1.0 -0.5 0.0 0.5 1.0 1.5
Grid Dots Hatching Paper Noise Paint Pigments Near-regular
patterns Irregular patterns
Cross- hatching
AC
E
1.2
1.0
0.8
0.6
0.4
AC
E
1.4
1.2
1.0
0.8
0.6
r² = 0.6992
r² = 0.9075
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• More suitable for low-contrast media
• Simple
• Strong motion coherence and temporal continuity
• Real-time animation
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l=0.5
l=0
l=1
Lmax
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Input: white noise seed
…
…
…
…
Parametric Texture Synthesis [PS00]
Seed Pyramid
Input: texture example
Output: SLAM
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Self-Similar Texture for Coherent Line Stylization, Bénard et al. 2010
2D Infinite zoom: Self-Similar Line Artmap (SLAM)
Propagation using a 2D buffer aliasing ambiguities
One brush stroke per line
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• Linear screen-space parameterization using Self-similar Line Artmaps
• Multiple brush strokes per feature line
• New propagation mechanism
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• Feature samples – lines extracted in 2D or 3D
3D position
Local tangent
2D velocity
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Snakes
Snakes
Tracking Advection Advection
3D scene
Lines extraction
Lines extraction
Feature samples
Relaxation Relaxation
Vectorization
Coverage Coverage Connectivity Connectivity
Line drawing
Brush Paths
Brush Paths
Geometry Geometry
Parameterization Parameterization
Stylization Stylization
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• 2D polylines active contours (Kass et al. 1988)
• Goals
Coherence continuous evolution across frames
Accuracy faithfully represent shape
Coverage Level of Detail
Simplicity simple topology
Length stylization freedom
Trac
kin
g V
ect
ori
zati
on
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• Directional coverage radius
• Local vectorization operators
Trim
Extend
Merge
Split
Coverage Coverage
Connectivity Connectivity
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Coverage Coverage
Connectivity Connectivity
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• Directional coverage radius
• Local vectorization operators
Trim
Extend
Merge
Split
• Applied sequentially in a greedy fashion
Coverage Coverage
Connectivity Connectivity
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• Reprojection similar to Kalnins et al. 2003
• Computed for feature lines only connection between contour and feature sample needed
Advection Advection
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• Minimize the energy:
• Re-sampling [DM00]
Relaxation Relaxation
External – Attraction by the features – Mass-spring forces prevents shrinking
Internal – Continuity – Smoothness
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Snakes
Snakes
Tracking Advection Advection
3D scene
Lines extraction
Lines extraction
Feature samples
Relaxation Relaxation
Vectorization
Coverage Coverage Connectivity Connectivity
Line drawing
Brush Paths
Brush Paths
Geometry Geometry
Parameterization Parameterization
Stylization Stylization
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• Consistently increasing subset of a snake
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• Uniform in screen-space linear arc-length parameterization :
avec = slope = phase = arc-length
• Evolve according to the motion and topology of the contours parameterization at each vertex
Parameterization Parameterization
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• Propagation at each vertex
Parameterization stored between two frames
Parameterization Parameterization
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• Propagation at each vertex
• Linearization (in the least-square sense) p
aram
eter
izat
ion
arc-length
Parameterization Parameterization
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• Propagation at each vertex
• Vectorization events
Split
Extend
Trim
Merge: mechanism to avoid parameterization discontinuities
• Linearization
propagated directly
Parameterization Parameterization
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• Only if the slope and phase match
• Leveling mechanism pushes the 2 parameterizations to their mid-value:
with
par
amet
eriz
atio
n
arc-length
Parameterization Parameterization
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• Feature lines dependency
Robustness toward noise / outliers
Temporal smoothing
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