Computer animation My office hours: Tue 1:00-3:00 PM, SAL 216 TA: - - PowerPoint PPT Presentation

Computer animation

Course 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

• f 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

• ne 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

• f 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

Traditional Physics-based Data-driven Performance- based Rigid body Deformable body Articulated body Face Hair and cloth Natural phenomena Synthesis Editing Compositing Simulation

Techniques Tools Objects

Traditional animation

That was then...

Film runs at 24 frames per sec; that is, 1440 pictures to draw in

• ne 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