Transcript Simulation tools in virtual worlds

Integration of simulation tools in
online virtual worlds
Stéphane SIKORA
AI Lab of Paris5 University
2nd conference on virtual worlds
5 July 2000
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Simulation tools and virtual worlds
• Online virtual worlds are generally inhabited by avatars.
 Use of simulation tools in order to enhance these virtual
worlds (physics, biology).
 Creation of autonomous entities (artificial life)
 Possibility to play around the original simulation
- Definition of a genotype for these entities
- Use of genetic operators
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2nd Garden Project
• 2 goals :
– Computer simulation of growth process. Our model of
plant is based on maize.
– Use of this tool for a Virtual World application, leading
to the development of a virtual garden. This project was
inspired by Nerve Garden (Bruce Damer).
• This project is the result of a collaboration :
• S. Sikora, D. Steinberg, C. Lattaud (LIAP5)
• B. Andrieu, C. Fournier (INRA Grignon)
• F. Lediberder, S. Maguet (Canal numedia)
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Plant development model
• Generally, modeling the growth
process of plants (at the level of
organs) requires:
– A model of the activity of the
apex (the organ responsible for
the initiation of new organs)
– A model of the other organs
activity
– An architectural model of the
plant, describing its geometric
structure.
– A model of the environment
A phytomer and its components.
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L-systems
• Most widely used model of plant development
(Lindenmayer, Prusinkievicz)
• Rewriting rules operating on strings of symbols.
– Axiom:
– Rule:
F
F  F[+F][-F]F
• Example of a graphical interpretation :
F : Move Forward
+ - : Rotations of PI/3
[ ] : Encloses a sub tree
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nd
2
garden: plant model
•Model based on a multi agent system:
-1 organ = 1 agent. Each organ has
its own behavior
- Synchronous simulation :
1 iteration = 1 simulated day)
-Communication capabilities
(endogenous flows)
-Local response to environmental
conditions
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Sensibility to the environment:
Effect of temperature
• Plants sharing the same genotype
• Continuous growing temperature field (from left to right)
• Temperature has an effect on the speed of growth, the shape
and the size of plants.
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Genetic factors
• Each plant is defined by a genotype composed of 50 genes.
The genes affect the organs behavior.
• Implementation of genetic operators (crossover, mutation)
to explore the plants space.
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Gene #17
• Gene #17: amount of leaves and buds by phytomer
• Direct effect of this gene on phenotype.
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Gene #28
• Gene #28: maximum speed of growth of leaves
• Indirect effect of this gene on inter-nodes size
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An evolution operator: crossover
• 10 different plants generated from the same
parents. This offspring is the result of a crossover
operator applied on the two parents.
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A new world...
• The 2nd World (2W) : www.2nd-world.fr
– Virtual community developed by Canal numedia.
– Famous places of Paris reconstructed in VRML
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Greenhouses in the 2nd World
• Each greenhouse has its own environmental conditions
(temperature, moisture, enlightenment...).
• 6 times a day, a step of the growth process is performed.
• Users will have the opportunity to grow their own created seeds
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PlanteStudio
• Interactive construction of
virtual seeds.
•Modification of the genes by use
of genetic operators
• Visualization of the growth
process
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PlanteStudio
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PlanteStudio
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Conclusion
• Original approach where the organs of plants are defined
by agents.
• Everything done with L-systems can be done with this
model.As biological models evolve quickly, the simulation
has to be easy to maintain. With multi agent system, this is
more straightforward and intuitive
• Coherent local response to the environment
• The communication between organs is easier to handle.
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Future work
• Improvement of the biological model:
– architectural model (roots)
– internal communication
– resource consumption
• Interaction between plants and users:
– modification of environmental conditions
– resource control
– on line experimental laboratory
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