character animation amy gooch cs395: introduction to animation 07.20.04
TRANSCRIPT
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
Copyright Digital character Animation2 vol 1 by George maestri
Posing and Anatomy
• Asymmetry in :– Posing– Motion
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Bad Symmetrical Posing and Action
Good Non-Symmetrical Posing and Action
Copyright ©1999 Michael B. Comet All Rights Reserved.
Weight
• Use 12 principles to imply weight:
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Copyright ©1999 Michael B. Comet All Rights Reserved.
Silhouette
Hard to tell what is going on in the silhouette
Copyright ©1999 Michael B. Comet All Rights Reserved.
Strong Silhouette
Copyright ©1999 Michael B. Comet All Rights Reserved.
Staging
Copyright Digital character Animation2 vol 1 by George maestri
Staging
Copyright Digital character Animation2 vol 1 by George maestri
Staging
Copyright Digital character Animation2 vol 1 by George maestri
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
Copyright ©1999 Michael B. Comet All Rights Reserved.
Snap
• TimingEase-in, Ease-out isn’t always necessary
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Top ball floats
Bottom ball snaps into place
Copyright ©1999 Michael B. Comet All Rights Reserved.
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Bad Floaty Action
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Good Snappy Action
Copyright ©1999 Michael B. Comet All Rights Reserved.
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
Copyright Digital character Animation2 vol 1 by George maestri
Walk Cycles
Copyright Digital character Animation2 vol 1 by George maestri
Walk Cycles
Copyright Digital character Animation2 vol 1 by George maestri
Walk Cylces
Copyright Digital character Animation2 vol 1 by George maestri
Walk Cycles
Copyright Digital character Animation2 vol 1 by George maestri
Walk Examples
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Copyright Digital character Animation2 vol 1 by George maestri
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
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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.
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Particle Systems Examples
• Cassidy Curtis
Particle Systems Examples
• Barbara Meier
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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
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Steering behaviors
• Cohesion: move toward the average position of local flockmates
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Steering behaviors
• Alignment: Steer towards the average heading of local flockmates
• Speed matching as well
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Obstacle Avoidance
• Force field– Problem: can’t move along a wall
• Steer-to-avoid– Silhouette from view point– Aim just outside that point
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Obstacle Avoidance and Goal Seeking
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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
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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
http://www.comet-cartoons.com/toons/3ddocs/lipsync/lipsync.html
Facial Animation
http://www.comet-cartoons.com/toons/3ddocs/lipsync/lipsync.html
Facial Animation
• Morphing Targets– aka Blend Shapes
• http://mambo.ucsc.edu/psl/fan.html
Facial Animation: Mouth
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Facial Animation: Eyes
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Facial Animation: Head
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Facial Animation: Mouth, Eyes, Head, and Body
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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)