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What is animation?

• Fake motion using rapidly changing images• – early animations: 16 i/s• – current rates: 25 or 30 i/s• – near-perfect smoothness: 70 i/s• Modifying scene parameters as a function of

time• Animate: give life (anime=soul)• Animation is part art, part science

Types of Animation

• Hand drawn animation (cel animation)– Pencil test– Ink and paint on overlays (cels), arranged over

the background (nowadays done using computers)

– Filming each frame

Hand drawn animation

• Pioneer cartoon animators (mainstream)– Walt Disney, Tex Avery, Walter Lanz

• Walt Disney hand drawn animated feature movies: – Snow white and the seven dwarfs (1937),

Fantasia (1940), The little mermaid (1989)

Types of Animation

• Stop-Motion animation– Move model, record each instance– Clay models, rubber skin over metal armatures

• Animatronics– Computer controlled mechanical models

animated in real time– Metal jointed armature, servomotors, synthetic

skin– Forward, inverse kinematics

Types of Animation• Performance animation

– Puppetry, actor inside a suit– Computer animation: motion capture

• Computer Animation– Assistive to classical animation– 2-D animation– 3-D animation

Types of Animation• Character Animation

– Highest form of animation• Effects animation

– Non-character, waves, fire, clouds, fireworks• Animated films• Animated characters in live action• Visual effects for live action

– Should match the live action (motion, color)

5

Why use computers ?

• Animation is expensive– 30 i/s

– 30 minutes = 54000 images

– 5 min/i, 12 hours/day ~ 1 year

6

Why use computers ?(continued)

• Use 3D geometry– precision

– realistic rendering

• Abstraction– provide laws

• Interactivity– simulators

– games

Different levels

• Low level: individual frames

• Medium level: sequences

• High level: story and message

• Computer helps all three levels

7

What can we animate ?

• Object positions and orientations

• Shape geometry

• Shape appearance

• Lightning

• Camera

• Anything else

Applications

• Films

• Games

• Data visualization

• Simulators

• Virtual environments

8

Films

• Entertainment– TRON, Toy story, Titanic

• Advertising

• Education

Games

• Interactivity– ping-pong

• Animated creatures– space invaders, pac-man

• Virtual worlds– simcity

• Multiple players in shared worlds– quake, parsec

9

Data visualization

• Weather

• Flows

• Differential systems

Simulators

• Design– Robotics

– Ergonomics

– Architecture

• Training– flight, drive, remote control

– surgery

– dangerous environments

10

Virtual environments

• Non-immersive environments– VRML worlds

– virtual shopping malls

• Immersive environments– virtual reality

– augmented reality

Computer Animation: Overview• Scripting• Keyframing• Kinematics• Motion Processing• Higher Level Animation• Dynamics and Simulation

Example of ScriptingSpecifying the parameters at every framedefine spinningCube()

rotAngle = pi*frameNumber / 50

define carScript()carTranslation = 10*(frameNumber / 100)wheelRotation = pi*frameNumber / 5

Keyframing•Specify only the important frames, interpolate the frames in-between•Used in traditional animation

What and how to interpolate is important

Keyframing

• Interpolation of position and orientation– Intrepolation of transformation matrices– Parameter curves, motion paths

• Interpolation of shape – Morphing, external control structures (lattices)

• Interpolation of attributes (color, texture, camera depth of field, light source intensity)

KinematicsThe study or specification of

motion, independent of the underlying physics that created the motion

Articulated Figure:A figure made up of a series of links (bones)connected at joints

State vector θProvide θ(t)

Forward KinematicsGiven the character’s state,

calculate its pose

Full control, requires skilled animators

)(θfX =

2θ

1θ

++++

=)sin(sin)cos(cos

21211

21211

θθθθθθ

llll

X

X

Inverse Kinematics•Given the character’s pose, calculate its state•Applied in articulated objects, multiple solutions, requires motion constraints•Limited control

)(1 Xf −=θ

X1θ

2θ

−−+++++−

=−

21

22

21

221

22122

22122

2)(cos

)cos()sin()cos()sin(

llllyx

xllylyllxl

θθθθ

θ

Motion Processing: input for forward kinematics

Motion Capture Motion Editing

Procedural animation

• Provide the rules-laws that govern the motion, let the system evaluate the positions/shape

Dynamics-Physics based animation

Using “physics” to define the animation, subset ofprocedural animation Model choice is important

θ

(1) (2)

mFV

VX

=

=

&

&

TL

FPVX

=

=

=

=

&

&

&

&

ωθmg

Can use “augmented” laws of physics

Dynamics-Physics based animation

• Point masses, rigid bodies, deformable bodies, articulated objects

• One should specify forces, material properties, initial conditions constraints

• Solving ordinary differential equations, inclusion of constraints

• Collision detection and handling

Dynamics – Particle SystemsParticle Systems [Reeves83]

Represent “fuzzy” objects (such as fire, smoke) as a collection of particles

Particles contain local statePositionVelocityAgeLifespanRendering properties

Dynamics – Rigid Bodies

Rigid BodiesIntegrationCollision detectionConstraints

Dynamics – Deformable Objects

Deformable ObjectsFFDElasticsFinite Elements

Dynamics – Cloth

Cloth SimulationStable IntegrationAdaptivityMaterial Properties

Behavioral Animation•Animating by describing an actor’s behavior•High level animation, related to AI and autonomousagentsAn actor’s behavior defines how the actor

interacts with other actors and the environment TRex()

if(player is close)eatPlayer()

else if(can see player)chasePlayer()

elsewander()

Behavioral Animation

Useful for crowd animations, games

Real Time AnimationZelda (GameCube)

Offline AnimationFinal Fantasy

• Facial animation– Facial expressions, lipsyncing (visemes),

emotions• Human figure animation

Development of Technology

• 1960’s– Mainframes, alphanumeric displays– In-house, not portable SW– First CADAM systems (GM, Boeing, IBM)– 3-D drawings plotted on paper and filmed to

produce animation (Boeing)– SketchPad: I. Sutherland, MIT– GE: primitive flight simulator


• 1970’s– First microcomputers, 8-bit, 10MhZ– Research at U. of Utah, z-buffering, Phong

Shading, texture mapping• 1980’s

– 1982: Silicon Graphics graphics workstations (Geometry Engine)


• 1980’s– 64-bit RISCs, graphics processors– Renderman shading language (Pixar, 1988)– Founding of pioneering 3-D graphics and VFX

SW companies: Alias, Wavefront, Softimage


• 1990’s– Windows NT and Linux dominate– SGI offers NT-based workstations– Powerful graphics processors, intranets,

rendering farms– Introduction of HD digital video– Computer games, platform games (Sony

Playstation, Sega Dreamcast, Nintendo 64): great demand for animators


• 2000’s– Powerful GPUs result in real time 3-D games

• Sony Playstation 2: 66M triangles per sec (average geometry complexity of Toy Story)

• Microsoft Xbox: 125M triangles per sec

– All digital feature film productions (Star Wars)– DVD proliferation

Visual Milestonesanimated films, VFX, games

• 1960’s – Computer animation works dominated by

engineers– 1962: Mr Computer Image ABC (computer

generated character animation)


• 1970’s– Voyager 2, 3-D computer animation (J. Blinn,

JPL)– The Joggler, computer key frame interpolation

(1974)– Creation of ILM (effects for Star Wars, 1977) – Pong game, 1972 (N. Bushnell), first

videogame


• 1980’s– Disney’s TRON 20min of computer animation

superimposed on live action– ILM creates VFX for Star Wars II+III (first

VFX shot created entirely with 3-D animation), Indiana Jones, etc

– Brilliance: first CG TV ad to be aired during SuperBowl


• 1980’s– Rise of leading production houses: Pixar,

Rhythm & Hues– Luxo Jr (1985), John Lasseter, Pixar, keyframe

animation– Knicknack (1989), Pixar, motion capture – Walt Disney starts using computer graphics and

animation (1985)– Little mermaid(1989): last film using traditional

animation.


• 1990’s– Terminator II (1991, ILM) simulation of human

motion, 3-D morphing– Jurassic Park (1993, ILM) inverse kinematics– Coca Cola Polar Bears TV ad (1993, Rhythm &

Hues)– Myst game: pre rendered 3D animation– The Rescuers Down Under(1990): first entirely

CG Disney feature film– Beauty & Beast, Lion King


• 1990’s– Toy Story (1995, Pixar) First feature animated

film produced by 3D computer animation– ANTZ (DreamWorks) A Bug’s Life (Pixar)– Terminator II (1991) 44 digital effects shots,

How the Grinch Stole Christmas (2000) 300 digital effects shots

– Games: Duke Nukem 3D, Age of Empires


– Location based entertainment: Volcano Mine Ride (1995, motion simulation)

• 2000’s– Spy Kids 2: first film shot entirely in HD digital

video– LOTR (2001) Golum, crowd animation, – Supporting, subtle VFX: Magnolia, American

Beauty– Monster’s Inc: 3M hair– Shrek 2, Finding Nemo, Chicken Little

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