Computer animationCourse website: http://www-scf.usc.edu/~csci520

My office hours: Tue 1:00-3:00 PM, SAL 216

TA: Sumit Jain

TA’s office hours: Wed 2:00-4:00 PM

Administrations

CS 480 or CS 580

Thorough understanding of linear algebra

Vector calculus

A good working knowledge of C and C++ programming

Prerequisites

Project (90%)

Paper presentation (5%)

Participation in the class (5%)

Grading schemes

Project 1: Animation system (15%)

Project 2: Constrained particle systems (25%)

Project 3: Inverse kinematics (25%)

Project 4: Final project (35%)

Projects Paper presentation

Find a parter (different from your project partner)

Choose a paper from the list

Sign up with the TA

You have 10 weeks to learn the materials

Come to my office hours if you need help

Graduated from the University of Washington, Dept of Computer Science and Engineering (2005)

Thesis topic: Towards a Generative Model of Human Natural Motion

Who am I?

Teach you every thing I know about Animation

Teach you how to find and formulate your research problems

Inspire some of you to do research with me

What do I expect?

A class that takes a lot of your time (I’m not kidding)

A class that forces you to work with real people

You need to brush off your linear algebra and calculus

Being a good programmer is not crucial, but it certainly helps

What should you expect?Animation in the silent era

(1900-1930)

“Felix the Cat (1923)”“Farmer Alfalfa & His

Terrytoon Pals (1916)”

“Gertie the Dinosaur (1914)”

Golden age of animation

(1930-1950)

“Tom and Jerry” (1940)

“Betty Boop (1930)” “Snow White (1937)” “Bugs Bunny (1940)”

“Fantasia (1940)” “Bambi” (1942)

Animation in television era

(1950-1980)

“The Flintstones

(1960-1966)”

“Mighty Mouse

(1950-1980)”

“Heckle and Jeckle

(1946-1966)”

Modern animation (1980-present)

“Toy Story (1995)”

“Final Fantasy (2001)”

“Jurassic Park (1993)”“The Little Mermaid (1992)”

“Half Life 2 (2004)”

Principles of animation

12 animation principles for creating character animation were developed at the Disney Studio in the 1930s

John Lasseter (Pixar) introduced them to the computer animation community in 1987 in a SIGGRAPH course

Question: how to support these principles in computer tools?

1. Squash and stretch

Character composed of living flesh that deforms to accurate movement

Exaggerate deformations emphasize motion and impact

Volume conservation is the key

2. Anticipation

Anticipation allows an animator to accentuate a character’s action as it directs the viewers attention

Can be as simple as facial expression or as broad as the body windup

Don’t surprise your audience unless it is intentional

2. Anticipation 3. Staging

Staging is the consideration of camera, framing and the position of characters

Staging can help to exaggerate action and impact

The audience’s eye must be led to exactly where it needs to be at the right moment

3. Staging

“Monsters Inc. (2001)”

4. Straight ahead and pose to pose

Two methods of drawing a scene

Straight ahead action starts with an idea in mind and draw all frames until done

Used for wild, scrambling action where spontaneity is important

Pose to pose draws the keyframes first and then fill in the in-betweens

Used for animation requiring precise acting and timing

4. Straight ahead and pose to pose

Which one is made by straight ahead action?

“The Incredibles (2004)” “Wallace and Gromit (2005)”

5. Follow through and overlap

Nothing stops abruptly in reality

Follow-through is also evident in secondary motion

Slight variations in timing and speed of loose parts make the object seem more natural

6. Slow in and slow out

To stress the keyframes, move slowly away from one keyframe, quickly in the in between frames, and slowly into the next keyframe

Used for exaggerating the acceleration and deacceleration occurring at the extremes

7. Arcs

Nothing living ever really move in a perfectly straight line

Most human motion happens on curved trajectories

7. Arcs 8. Secondary actions

Action aside from the of the primary character

Must not distract the audience

Often reveal subtle emotions or hidden thoughts

9. Timing

Timing plays an essential role in illustrating the emotional state of a character

Timing can also define the weight and the inertia of the characters

10. Exaggeration

Walt Disney wanted exaggeration with believability

Used to increase the readability of emotions and actions

Exaggerated poses often look ridiculous when viewed as stills, but they add essential impact when viewed in a split second

11. Solid drawing

Drawing motion is a critical activity for animators

Observation improves the fundamental skills of composing a scene, character proportions, and timing

Also allows the rapid development of ideas before committing a design to screen

12. Appeal

Appeal is what makes people want to look at a character

Even a villain can have appeal

A design that is complicated or hard to read lacks appeal

Luxo Jr.

How many animation principles does Luxo Jr. follow?

Beyond entertainment

Biomechanics

Robotics

Scientific visualization

Education

Anthropology

Animation research

TraditionalPhysics-basedData-driven

Performance-based

Rigid bodyDeformable bodyArticulated body

FaceHair and cloth

Natural phenomena

SynthesisEditing

CompositingSimulation

Techniques ToolsObjects

Traditional animation

That was then... Film runs at 24 frames per sec; that is, 1440 pictures to draw in one minute

Artistic vision has to be converted into a sequence of still “keyframes”

Hard to draw consistent “in-between” frames

Not enough to get the still right; must to look right at full speed

Computer assisted animation

This is now

Generate the images by rending a 3D model

Manually set the parameters for each keyframe

Automatically interpolate between two drawings to produce inbetweens

Traditional animation

Do computers really expedite the process of creating animation?

That was then... This is now

Physics-based methods

Generate motion by applying physical laws

Simulate physical phenomena associated with motion

gravity

momentum (inertia)

collisions

friction

deformation

fracture

Physics-based methods

Rigid body simulation

Fast frictional dynamics for rigid bodies

Kaufman et. al. Siggraph 2005

Physics-based methods

Rigid body simulation

Deformable object simulation

BD-Tree: Output-sensitive collision detection

for reduced deformable models

James et. al. Siggraph 2004

Physics-based methods

Rigid body simulation

Deformable object simulation

Character animation

Learning physics-based motion style

with nonlinear inverse optimization

Liu et. al. Siggraph 2005

Physics-based methods

Rigid body simulation

Deformable object simulation

Character animation

Natural phenomena simulation Water drops on surfaces

Wang et. al. Siggraph 2005

Data-driven methods

Human motion

Motion synthesis from annotations

Arikan et. al. Siggraph 2003

Data-driven methods

Facial animation

Human motion

Automatic determination of facial

muscle activations from sparse

motion capture marker data

Sofakis et. al. Siggraph 2005

Data-driven methods

Facial animation

Human body deformation

Human motion

SCAPE: Shape completion and

animation of people

Anguelov et. al. Siggraph 2005

Performance-based animation

Record the animation from live action

rotoscope: trace over video of real motions

motion capture: track motion of reference points in 3D

The making of LOTR

Useful math

Differential equations

Optimization methods

Statistical models

Useful background knowledge

Physics

Mechanics

Biomechanics

What’s next?

Keyframe animation

Interpolation using cubic splines

Speed control