Character Animation Amy Gooch CS395: Introduction to Animation 07.20.04.

Character Animation

Amy Gooch

CS395: Introduction to Animation

07.20.04

Dancing Baby

• http://www.burningpixel.com/Baby/Babygif.htm

Dancing Baby

• http://www.burningpixel.com/Baby/Babygif.htm

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Proportion: Head and Body

• Realistic Character– 6 to 8 heads high

• Cartoon Character– Little more than 2 heads high

Proportion: Eyes

• Size– Small eyes -> mean, angry– Big eyes -> innocence, cute

• Placement– Higher = younger

Proportion

• Feet– Realistic: almost as long as forearm

• Hands

More..

• Planning ahead

• Block, then Refine

Copyright ©1999 Michael B. Comet All Rights Reserved.

Posing

• Balance

Copyright Digital character Animation2 vol 1 by George maestri

Line of Balance


Posing and Anatomy

• Asymmetry in :– Posing– Motion





Bad Symmetrical Posing and Action

Good Non-Symmetrical Posing and Action


Weight

• Use 12 principles to imply weight:








Silhouette

Hard to tell what is going on in the silhouette


Strong Silhouette


Staging


Moving Holds

• If animation stops, it dies– Something should at least slightly move

• (eyes, antenna, etc)

Emotion

• Happy -> Move faster

• Sad -> Move Slower

(luxo jr)

Readability of Actions

• Timing

• If too fast– audience will miss

• (unless action properly grabs eye)

– Can’t understand it

• Only one idea seen by audience at a time

More…

• Intentionality– “Don’t move anything unless you understand

its purpose” ~Ollie Johnston

• Isolation / Control– Be able to move the head without moving the

shoulders


Snap

• TimingEase-in, Ease-out isn’t always necessary



Top ball floats

Bottom ball snaps into place




Bad Floaty Action



Good Snappy Action


Good Example :• Anticipation• Fast inbetweens• Follow-through• Secondary action

Snap: Mean Bug

• Non-symmetrical posing• Appeal• Arcs (watch the hands).• Overlapping action

Give Life to a..

• Story

Ask Why…

• animation• story• design• staging• animation• editing• lighting• Sound

Animation

– Comet Cartoons http://www.comet-cartoons.com/toons/anims.cfm

– Pipe Dream http://animusic.com/dvd-info-video.htm

– The ChubbChubbs http://animusic.com/dvd-info-video.html

– The Cathedral by Tomek Baginski and Platige Image

– Marc Tetro http://www.marctetro.com/animation/animation.htm

– Siggraph Video Review• http://www.siggraph.org/publications/video-review/sig2002/141.shtml

• • After you

– Christopher Cordingley, Ringling School of Art and Design

• Early Bloomer– Sony Imageworks– http://www.imageworks.com/films/earlybloomer/

• Lorenzo– Disney–

Walk Cycle

• Enough movement for one loop

• Repeatable

Walking


Walk Cycles


Walk Cylces


Walk Cycles


Walk Examples

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Run Examples

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Other kinds of animation…

07.21.04

Amy Gooch

Introduction to Computer Animation

Camera: Panning and Tilting

• Camera position is stationary• Rotates

– Horizontal (panning)– Vertical (tilting)

• Used to– Follow a moving character/object– Show more than can fit into a single frame– Transition from one camera position to another

• Problems:– Strobing– Tearing

• In CG add motion blur

Camera: Dolly and Tracking

• Dolly– Movement is parallel to camera lens

• Tracking– Movement is perpendicular to camera lens

• Used for realistic motion Miles per hour Feet per second Number of Frames to

move 10 feet at 30 fpsCasual stroll 2 2.9 102Average walk 3 4.4 68Brisk walk 4 5.9 51Average jog 6 8.8 34Average run 8 11.7 26All out sprint 12 17.6 17Car 30 44 7

Camera: Crane and Boom

• Camera moves up or down

• Same considerations for panning and tilting– Used to

• Follow a moving character/object

• Show more than can fit into a single frame

• Transition from one camera position to another

Zoom and Vertigo Effect

• Zoom = variable focal lengthCamera appears to move without moving



Procedural Animation

• Rule based– Particle Systems– Flocking– Goal Oriented

• Grasp and manipulation

• Gesture

– Crowd Animation?

Flow: http://www.reptilelabour.com/software/flow/

• f l o w allows one to interactively construct sophisticated particle systems and render the results either in real-time via OpenGL or off-line by a RenderMan compliant renderer.

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Flow: http://www.reptilelabour.com/software/flow/

• f l o w allows one to interactively construct sophisticated particle systems and render the results either in real-time via OpenGL or off-line by a RenderMan compliant renderer.







Particle Systems Examples

• Cassidy Curtis

Particle Systems Examples

• Barbara Meier



Painterly Rendering for Realtime Applications (2003) by Daniel Sperl is a realtime implementation in the Cg language of painterly rendering inspiried by Meier. http://www.incognitek.com/painterly/The site includes a thesis (in German, PDF 1.1MB), a paper (in English, PDF 1MB), images, movies, source code and an application.

Flocks, Herds, and Schools: A Distributed Behavior Model

Craig ReynoldsSIGGRAPH 1987

Amy Gooch

Motivation

• Flock of birds

• Herd of land animations

• School of fish

• Crowds of people

– How to encorporate geometry with group motion and animation?

Look to nature

• Flock is made of discrete bird

• Yet motion is fluid, random, synchronized

• Impression of intention and control– Yet biologic evidence:

• Flock motion is aggregate result of actions of individual animals

• Each animal acts on basis of its local perception of the world

Assumptions

• Flock = interaction between individual behaviors of birds

• Simulate flock by simulating individual

• Gloss over wing, fin, leg motion

• Simulate motion along path– Shape changing can be done separately

Simulating Flocks

• Related to particle systems– Particles are replaced by entire geometric

object, called a “boid”– boids

• orientation

• more complex behaviors– Internal and external state

• interaction

Terminology

• Origin of term “Boids”– Abbreviation of “birdoid”

– Inspired by Tom Duff at NYIT’s primitive shape based upon ellipsoids, called “soids”

– Mel Brooks film: “The Producers” with Zero Mostel and Gene Wilder; Scene about keeping pigeons on roof: “You used to be able to sit on the stoop like a normal person, but not any more, 'cause of da BOIDS. Dirty, lousy, stinkin' BOIDS"

Flocking

• Local vs global knowledge– Global can be bad– Know about:

• Itself

• Its near neighbors

• The flock

• Neighborhood:– Distance from center of boid– Angle from flight direction

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Steering behaviors

• Separation: avoid crowding local flockmates



Steering behaviors

• Cohesion: move toward the average position of local flockmates



Steering behaviors

• Alignment: Steer towards the average heading of local flockmates

• Speed matching as well



Obstacle Avoidance

• Force field– Problem: can’t move along a wall

• Steer-to-avoid– Silhouette from view point– Aim just outside that point



Obstacle Avoidance and Goal Seeking



Combining behaviors

• Weighted sum

• Prioritize– Eg: flock centering can be ignored in favor of

obstacle avoidance

Algorithmic Considerations

• Naïve: O(N2) with flock’s population

• Separate processor for each boid: O(N)

• Dynamic spatial partitioning of flock: – Toward constant time

• Collision Detection: N2 – Unless done incrementally– Based upon previous state

Animating

• Impromptu Flocking

• Scripted Flocking

Animation

• Stanley and Stella in : Breaking the Ice– SIGGRAPH 1987 Electronic Theater– Symbolic Graphics Division and

Whitney/Demos Productions

Boids since 1987

• Artificial Life

• Simulate interaction of autonomous agents

• Check out:– http://www.red3d.com/cwr/boids/

– http://www.red3d.com/cwr/boids/applet/

Steering Behaviors For Autonomous Characters

• Simple behaviors for individuals and pairs:

Seek and Flee Pursue and EvadeWanderArrival Obstacle Avoidance Containment Wall Following Path Following Flow Field Following

By Craig Reynolds,Game Developers Conference 1999 Paper (And OpenSteer source code)

• Combined behaviors and groups:

Crowd Path FollowingLeader FollowingUnaligned CollisionAvoidance Queuing (at a doorway)Flocking

In Productions..

• 1992: Batman returns– Bat swarms and penguin flocks

Motion Capture• http://www.platige.com/katedra/eng_/making_of_animation.html

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The Cathedral

• http://www.platige.com/

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MANTIS by Grzegorz Jonkajtys



Facial Animation

• High frequency periodic motion– Mouth articulation during speech

• Low frequency periodic motion– Blinking

• Non-periodic motion– Changes in emotional state

– Smiling ;)

Facial Animation

• Verbal cues– Phonems

– Most people use 9:

http://www.garycmartin.com/phoneme_examples.htmlhttp://www.comet-cartoons.com/toons/3ddocs/lipsync/lipsync.html

http://www.comet-cartoons.com/toons/3ddocs/lipsync/lipsync.html

Facial Animation

• Non-verbal cues– Secondary actions

• Eyes, Eye brows, lips, nose

• Skin


Facial Animation


Facial Animation

• Morphing Targets– aka Blend Shapes

• http://mambo.ucsc.edu/psl/fan.html

Facial Animation: Mouth



Facial Animation: Eyes



Facial Animation: Head



Facial Animation: Mouth, Eyes, Head, and Body



Physics and Animation

• Physical Properties– Weight / Mass

– Rigid, elasticity, stiffness

– flexible

• Distance /Time

• Forces– Local vs Global– Impacting– Attracting– Resisting– Friction– Resistance

• Wind / air / Viscosity(environmental density)

– Gravity

Animations

• Rhythm and Hues DVD

Credits / Resources• http://www.siggraph.org/education/materials/HyperGraph/animation/cameras/

traditional_film_camera_techniqu.htm

• http://www.ijmc.com/ijmc/texts/cartoon• http://www.tutorialized.com/tutorials/Maya/4• Physically Based Modeling Course

– http://www.pixar.com/companyinfo/research/pbm2001/index.html

• Artificial Life– http://mrl.nyu.edu/~dt/siggraph97-course/

– http://www.siggraph.org/education/materials/HyperGraph/animation/character_animation/principles/ollie_johnston.htm

Animations I’m still looking for..

– Blockbuster Tippett Studios (CG)– Loco Rodeo by Mondo media– Aerobot by Polygon Pictures / IPA / NK-EXA– Masks (SIGGRAPH 1999 Piotr Karwas)– Polygon Family– Fashion Parade (Ex machina)

Character Animation Amy Gooch CS395: Introduction to Animation 07.20.04.

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