self-similar texture for coherent line stylization, npar2010
DESCRIPTION
Presentation of our paper called "Self-Similar Texture for Coherent Line Stylization" published at NPAR 2010TRANSCRIPT
Pierre Bénard ……………… Grenoble University
Forrester Cole ……………… MIT CSAIL
Aleksey Golovinskiy …… Princeton University
Adam Finkelstein
Self-Similar Texture
for Coherent Line Stylization
Line stylization
2
Pablo Picasso, 1949Lithograph for the International Peace Congress
Andy Wakeley - Cheetah bounding sketch
IFÖ Cera wall mounted bidet 4016
Line stylization
3
0
l
Brush path
Line texture
Contributions
4
Coherent Parameterizationof View-Dependant Lines
Self-Similar Line Artmaps
Mapping Policies
5
• Stretching
• Tiling
Mapping Policies
6
• Stretching
Temporally coherent
Stretch or compress the texture
• Tiling
Mapping Policies
7
Mapping Policies
8
• Stretching
Temporally coherent
Stretch or compress the texture
• Tiling
Preserve the texture characteristics
Incoherent sliding
Mapping Policies
9
• Artmaps, Klein et al. 2000
• Tonal art map, Praun et al. 2001
Coherent transition
Blending artifacts
Restricted zoom
Mapping Policies:
Previous work
10
• Texture Fractalization, Cunzi et al. 2003 / Bénard et al. 2009
Infinite zoom
Pattern degradation
Mapping Policies: Previous work
11
+
Mapping Policies
12
• Stretching
Temporally coherent
Stretch or compress the texture
• Tiling
Preserve the texture characteristics
Incoherent sliding
• Fading / Artmaps
Smooth and coherent transitions
Blending artifacts
Mapping Policies
13
SLAMs
14
SLAM Definition
15
Lmax / 2
Lmax
16
SLAM Properties1) Density
2) Smooth variation
17
SLAM Properties3) Self-Similarity
18
SLAM Properties3) Self-Similarity
SLAM Properties
19
l=0.5
l=0
l=1
Lmax
Artmap Construction
20
• Manual:“Styles” in Google SketchUp (up to 7 levels)
• Multi-scale Texture synthesis, Han et al. 2008
Infinite zoom
Coherence
Pattern at multiple scales
Costly synthesison the fly
Previous work
21
SLAM Synthesis by Example
22
• Parametric texture synthesis, Portilla and Simoncelli 2000
• Property: (empirical observation, no formal proof)
small change in seed small change in output
SLAM Synthesis by Example
23
Input: white noise seed
Seed Pyramid
…… Input: texture example
Output: SLAM
……
Parametric Texture Synthesis
Seed Pyramid Construction
24
=
Wsource Wf
Seed Pyramid
Wf
[WfWf]
0.5
1
α Wf + (1-α) [WfWf]
α=2 -1
Lmax
Lmax
Lmax / 2
SLAM Synthesis by Example
25
Results: synthesis
26
Examples Synthesized textures
Results: live demo
27
Contributions
28
Self-Similar Line Artmaps
Coherent Parameterizationof View-Dependant Lines
3D Lines
29
• Creases• Ridges and valleys
• Silhouettes• Suggestive contours• Apparent ridges
Fixed Lines View-Dependant Lines
• Coherent Stylized Silhouettes,Kalnins et al. 2003
Very good coherence
Tradeoff between 2D and 3D
Complex and brittle
Simpler optimization for 2D arc-length parameterization
Previous work
30
• Parameterization: T(s) = s + = slope = phases = 2D arc-length
• Goal:
find ( , ) such that T(s) best fit the parameterization of the previous frame.
• 3 steps process in 2D screen-space
Screen-space coherence
31
1. Propagate Parameters
3. Render Strokes
Pipeline
32
2. Update Parameters
frame f
frame f+1
Parameters propagation
34
si
p
d
• Sample visible paths: si
• Splat parameterization:ti = si +
• Weighted by:wi(p)= clamp(1-d/,0,1)
exact parameterization along the spine of the line
• Contrary to Kalnins et al. 2003:
No item buffer (aliasing artifacts)
No local search
Additional controls:
– Size of the sprite: propagation vs. overlapping
– Weights: partial visibility / z-depth
Parameters propagation
35
1. Propagate Parameters
3. Render Strokes
Pipeline
36
2. Update Parameters
frame f
frame f+1
Parameters update
38
• RANSAC fitting [Fischer and Bolles 1981]
• Similar in spirit to Bourdev, 1998Mix information from multiple paths
Popping when paths merge
Parameters update
39
1. Propagate Parameters
3. Render Strokes
Pipeline
40
2. Update Parameters
frame f
frame f+1
Results
41
Results
42
• Synthesized texture quality
• Parameterization propagation2D screen-space buffer insufficient
Limitations and future work
43
SLAMs provides:
• Temporally coherent line stylization
• For 2D and 3D animations
• Including view-dependant features with our screen-space coherent parameterization
Conclusions
44
SLAMs synthesis source code and dpix viewer:
http://www.cs.princeton.edu/gfx/proj/dpix
Thank you for your attention
45
46
Results: 2D animation
47
Results: fixed 3D lines
48