Physical Based Animation/Simulation Lecture Notes (What's on Midterm)

Physical Based Animation/Simulation Lecture Notes (what's on midterm). Week 9

Review these notes with ppt slide from lecture. http://www.sfu.ca/iat445

You need to know this slide 1 chart:

Slide 2:

Particle Systems

-  Particle systems offer a solution to modeling amorphous, dynamic and fluid objects like clouds, smoke, water, explosions and fire.

Slide 4:

1)  New particles are generated into the system.

2)  Each new particle is assigned its individual attributes.

3)  Any particles that have existed past their prescribed lifetime are extinguished.

4)  The remaining particles are moved and transformed according to their dynamic attributes.

5)  An image of the particles is rendered, often using special purpose algorithms.

Slide 15

•  Flocking is also generally the same field as Schooling or swarming or herding or crowd sequences

•  Flocking was started by Craig W. Reynolds with his boids work,

•  Boids is a complex word created from birds and oids

•  Flocking uses 3 simple rules - Separation, Alignment, Cohesion to create emergent behavior

Slide 16

•  Combination of three flocking rules results in emergence of fluid group movements

•  Emergent behavior

–  Behaviors that aren’t explicitly programmed into individual agent rules

Slide 17:

Three Rules of flocking (Steering Behaviors)

1.  Separation: steer to avoid crowding local flockmates.

2.  Alignment: steer toward the average heading of local flockmates.

3.  Cohesion: steer to move toward the average position of local flockmates.

Slides 30-31

One technique of Autonomous Behavior is the use of state machines. State machines :

1.  Separate the motion or behavior into several simple states

2.  Simple states allow us to generate laws

3.  State transitions are triggered by events

Slides 32-34

Another major AI –based technique for creatures with autonomous behaviors is Genetic Algorithms. Genetic Algorithms create populations of creatures through Darwinian Evolution.

With Genetic Algorithms the genotype and the phenotype have a direct relationship. The genotype is the ‘genes’ or program instructions which represents the phenotype which is the creature.

•  Recipe for a successful evolution in using Genetic Algorithms

1.  Create initial genotypes

1.  From scratch

2.  Calculate survival ratio

3.  Evaluate fitness and kill off the weaklings

4.  Reproduce the most fit

5.  Evolve, and proceed to step 3.