interactive design of botanical trees using freehand sketches and example-based editing makoto okabe...
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Interactive Design of Botanical Trees using Freehand Sketches and Example-based Editing
Makoto Okabe1, Shigeru Owada1,2 , Takeo Igarashi1,3
The University of Tokyo1, Sony CSL2,
JST PRESTO3
• Introduction– Motivation– Previous Work– Our method
• User Interface
• Details
• Result
• Discussion
Motivation
• 3D trees are important in– Cityscape design– Virtual reality– Consumer games
• 3D tree modeling is difficult– Enormous structural complexity
Previous Work
• Rule-based approaches– L-systems– Xfrog– SpeedTree
Difficult for novices
• 3D tree libraries– Maya - Paint Effects
Difficult to design an arbitrary tree
2D sketch 3D model
Sparse Dense
• For quick and easy design of trees, we propose– Sketch-based modeling
Our method
– Example-based modeling
• Introduction
• User Interface– Modeling Process– Demonstration
• Details
• Result
• Discussion
Modeling Process
(a) 2D Sketch (b) 3D Construction (c) Multiplication
(e) Propagation(d) Leaf-arrangement
Demonstration
• Introduction• User Interface• Details
– Creating a 3D Tree from a 2D Sketch– Extension of the Basic Algorithm– Creating a Branch with Spiral Structure– Example-based Leaf Arrangements
• Result• Discussion
Creating a 3D Tree from a 2D Sketch
• Decide depths of branches• Keep the appearance from the view point• Resulting shape has infinite possibility
Creating a 3D Tree from a 2D Sketch
• Observation of natural trees– A natural tree spreads their branches to absorb sun
light as efficiently as possible
– The distances between a branch and other branches tend to be as large as possible
Creating a 3D Tree from a 2D Sketch
• Decide depths of branches one by one• Compute distances between branch shadows• Maximize distances among branches
• Other constraints– A 3D hull obtained from the 2D convex hull
• Keep the overall shape of a tree
– Length of a branch– Angle between two branches
Creating a 3D Tree from a 2D Sketch
2D Convex Hull 3D Hull
Extension of the Basic Algorithm
• Problem of the described algorithm– Front view is kept– Side view is strange
side view
front view
People omit branches spreading backward or forward
Extension of the Basic Algorithm
• simple ad hoc trick
basic algorithm
rotated version(by 90 degrees)
mergingmerging
90 degrees
Extension of the Basic Algorithm
• The resulting 3D tree– Front and side views look similar
front view
side view
Creating a Branch with Spiral Structure
• Decide depth values so that the branch stroke has a constant 3D curvature
– [Floral diagrams and inflorescences, Ijiri et al, SIGGRAPH 2005]
(a) (b) (c)
Calculate yi so that
Resulting 3D Trees
• 2D sketch resulting 3D tree models
• Three types of leaf arrangements
AlternatingGeminatus Whorled
Example-based Leaf Arrangements
Geminatus
Whorled
Alternating
Example-based Leaf Arrangements
• Introduction
• User Interface
• Details
• Result– Designed by Experts– Designed by Test Users – Comparison to Other Systems
• Discussion
Designed by Experts
(a) young tree (b) zelkova (c) maidenhair
7,900 nodes 30,000 nodes 4,300 nodes
Designed by Test Users
(d) 9 min (e) 6 min (f) 6 min
(a) 6 min (b) 8 min (c) 7 min
• L-system, Xfrog and our system
• Recruited 3 novice users(A, B, C)– L-system (A and B together)– Xfrog (C)– Our system (A, B, C individually)
• Photograph of a target tree
Comparison to Other Systems
Comparison to Other Systems
Photograph L-system ( 60 min ) XFrog ( 30 min )
Photograph Our method (10 min) Our method (10 min)
Comparison to Other Systems
• Our system– The major branching structures by sketching
• The other systems– Detailed structures produced by rules
Comparison to Other Systems
• Introduction
• User Interface
• Details
• Result
• Discussion– Summary– Limitations and Future Work
Summary
• We proposed a system for quick and easy design of 3D trees– Creating a 3D Tree from a 2D Sketch– Example-based modeling
• The user can design a tree intuitively, especially major branching structures– User Tests– cf) Rule-based systems
Limitations and Future Work
• Incorporating more natural phenomena– e.g.) Tropisms from user-defined branches
• Construction of forest
• Editing operations
– move, rotate, or bend
Thanks
• contact information– Makoto Okabe ([email protected])
• www for this project– http://www-ui.is.s.u-tokyo.ac.jp/~makoto21
• Thanks very much– This work was funded in part by the Japanese
Information-Technology Promotion Agency (IPA)– Eurographics reviewers