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Ping Tan et al.
Proceedings of ACM SIGGRAPH Asia 2008
Ja Min Jeong
2010/09/21
Korea University
Computer Graphics Lab.
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 2 KUCG |
Abstract
Single Image User Input
3D Branch Reconstruction
Leaves Reconstruction
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 3 KUCG |
1. Introduction
• Trees
Ubiquitous
Hard to model • Large varieties
• Natural complexity in geometry
• Useful
Movie
Architectural designs
Games
Web Applications
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 4 KUCG |
1. Introduction
• Previous Method
Amount of efforts -> good results • Many Parameters, Many images, 3D reconstruction
• Remarkably simple & Convincing results
Single image
Few user drawn strokes
Non-parametric synthesis
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 5 KUCG |
Overveiw
Single Tree Image User Input
Foliage (red) GrabCut Foliage extraction
Branch (blue) Gaussian mixture
model Branch Tracing
Leaf Texture
synthesis
SubTree Example New branch
synthesis
Branch
Pruning Branch Complete Generation leaves
Gaussian mixture
model Gibbs energy GrabCut
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 6 KUCG |
1.1 Related work
• Gaussian model
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 7 KUCG |
1.1 Related work
• Gaussian mixture model
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 8 KUCG |
1.1 Related work
• Gaussian mixture model
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 9 KUCG |
1.1 Related work
• GrabCut
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 10 KUCG |
1.2 Our approach
• Image based Tree Modeling [Ping Tan et al.]
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 11 KUCG |
1.2 Our approach
• Sketch based method
Interactive Design of Botanical Trees using Freehand Sketches and Example-based Editing [Makoto Okabe et al.]
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 12 KUCG |
2 Image Plane Sketching
• 2.1 User interface
Foliage region(red)
Branch stroke(blue)
• Not satisfied with this result
Adding or Deleting strokes for correction
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 13 KUCG |
2.2 Foliage extraction
• Foliage extraction
GrabCut
Gaussian mixture model • Mixture of 10 Gaussians
• Four components (Foliage) : green or red Gaussian
• Six components (background)
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 14 KUCG |
• Weight : Gibbs energy
• Foliage
• Background : indicates the RGB values at pixel x
: GMM parameters
2.2 Foliage extraction
S T
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 15 KUCG |
• Gibbs energy
= 1 : Background pixels
= 0 : Leaf pixels
: set of all 4-neighbor pixel pairs
• constant (strength of smoothness) : 60 in our implementation
2.2 Foliage extraction
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 16 KUCG |
2.3 Visible branch tracing
• Lazy Snapping[Yin Li et al.]
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 17 KUCG |
2.3 Visible branch tracing
• Lazy Snapping[Yin Li et al.]
• Circle radius > branch radius
•
: 0 (branch pixel) 1 (others)
: branch Gaussian parameter
: non-branch Gaussian parameter
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 18 KUCG |
2.3 Visible branch tracing
• Not satisfied with this result (Add and Del)
• Discarding redundant joints (simplied)
• Circle radius is fixed (50 pixels) all examples
• Branch radius to 75% of its parent
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 19 KUCG |
3 Tree Growing
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 20 KUCG |
3.1 Growth engine
• Initialization
Conversion of 2D branches into 3D
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 21 KUCG |
3.1.1 Initialization
• Creation of the library
Elementary subtrees
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 22 KUCG |
3.1.2 Non-parametric synthesis
New branches grow at the end of its `supporting branch‘
New branches can grow along the `supporting branch'
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 23 KUCG |
3.1.2 Non-parametric synthesis
Selection of a
branch to be
replaced
Selection of a
replacing library
subtree
Branch pruning
Check Threshold
in Section 3.2
Iteratively about 100 times
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 24 KUCG |
3.1.2 Non-parametric synthesis
• Selection of a branch to be replaced Larger radius and Older generation
• Selection of a replacing library subtree Add predefined subtrees: type I, type II or both
The rotation angle (12 levels of 360 degrees)
The scaling factor (same length as the replaced branch)
• Branch pruning Pruned by the extracted foliage Silhouette
removed, new branches if they are too close to some existing branches
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 25 KUCG |
3.2 Data-driven attractors
• Desired tree volume
2D (weakly controls) 3D (better)
• Image attractors
Growth is then driven by minimizing a cost
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 26 KUCG |
3.2 Data-driven attractors
• Extrapolated 3D attractors
How to 2D -> 3D ?
Foliage region • Tree is rotated 90 degrees around its main trunk
• Merged with the original one
Branch • Take the set of branch joints of the current tree
• Rotate these joints 90 degree around the main trunk
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 27 KUCG |
3.2 Data-driven attractors
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 28 KUCG |
3.2 Data-driven attractors
• 2D
• 3D
Top Veiw Side Veiw
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 29 KUCG |
3.2 Data-driven attractors
• Speedup
Computation of the distances • Distance computation in previous iteration can be reused
: newly created branches (red)
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 30 KUCG |
4 Completing the Tree
• Leaves of the tree
Synthesized from the recovered branch structure and textured
a at rectangle leaf size • (1/10 of main trunk radius)
Proportional to Branch length • 50 ~ 200 leaves
Arrangement of the leaves • Randomized
Leaves texture <- input image
leaf shape, leaf size, density and arrangement of leaves -> parameterized
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 31 KUCG |
Result
• 20 minutes
• PC with 2.4G CPU
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 32 KUCG |
Result
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 33 KUCG |
Result
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 34 KUCG |
Limitations
• Less similar to the original tree at different veiws
A database of real 3D branches might be helpful
• Less leaf detail
Cannot model large leaves
Cannot model flowers
• Interaction to mark out tree
Cannot handle very large scale data
Korea University Computer Graphics Lab.
Ja Min Jeong | 2011/09/21 | # 35 KUCG |
Conclusion & Future Work
• Simple and effective system Single image
Minimize user interaction
Amateur user : Sketch few strokes
• Previous multi-views methods -> Single image
• Modeling procedure fully automatic Automatic tree detection
Visible branch tracing algorithm