1. Mar. 30, 2001 Xiaoyuan Tu and Demetri Terzopoulos, Dept. of CS, University of Toronto Artificial Fishes: Physics, Locomotion, Perception, Behavior Presentation by Siddharth Dalal

2. Intro & Background What do fish do? –eat, survive, when compelled by their libidos…. Physics based graphic modeling Worm Dynamics, facial model –more sophisticated spring mass model advanced behavioral animation Any fish is good if caught on the hook.

3. Overview Intention focuses sensory data causing behavior

4. Fishics 1 - Mechanics Spring Mass Model m = mass x = position q = damping factor w = net force due to springs f = external force

5. Fishics 2 - Hydrodynamics Swimming - Muscles + Hydrodynamics

6. Fishics 3 - Motor Controllers Swim MC Left and right MC Anterior and Posterior of fish - r1, s1, r2, s2 Max params scaled from 0 - 1 to produce varying speeds

7. Sensory Perception Two on board environment sensors: –Vision Sensor - extracts information from scene geometry, object database, physical simulation. Cyclopean(?) vision - 300 o viewing angle. –Temperature sensor - senses ambient temp. at center of body

8. Behavio(u)r 1 Intention based on –Habits –Mental State –Incoming Sensory Information decides behavior routine incremental - needs memory

9. Behavior 2 - Habits and Mind Habits - does fish like brightness, schooling, male or female (yes this is in habits) Mental State –Three mental states - HLF - hunger, libido, fear –H= min[1-n(t)R(Δt)/α, 1] –L=min[s(Δt)(1-H(t)), 1] –F=min[Σf, 1], f=min[D/d(t), 1] (Fish like sex after dinner )

10. Intentions 1 Intentions –avoid, –escape –school –eat –mate –leave –wander

11. Intentions 2 Features of Generator –Persistence in intentions - no dithering –focusser - focus on most important intention Create ‘abnormal fish’ –warp intentions

12. Intentions 3 Behavior routines: –eight - avoid static obstacle, avoid fish, eat, mate, leave, wander, escape, school –chasing target subroutine –other subroutines - looping?, circling, ascending?, nuzzling

13. Fish Type = Warped Intentions Artificial Fish Types –Predators don’t escape, mate or school always cruise, so don’t leave

14. Fish Type = Prey Fish Grey Fish Artificial Fish Types –Prey school evade predators

15. Pacifists Artificial Fish Types –Pacifist no school, no escape just mate complex mating behavior implemented… –fish i chooses partner j –criteria if i is female/male –looping, circling, chasing-target, nuzzling –etc.

16. Result 10 fish, 15 food particles, 5 static obstacles at 4fps on SGI R4400 Indigo2 Future: –reproduction –other work

17. Links http://www.dgp.toronto.edu/people/tu/tu.html http://citeseer.nj.nec.com/tu94artificial.html http://www.cs.toronto.edu/~dt/

18. Guests and fish start to stink after two days.