Animation Introduction We are going to study

Animation

Introduction We are going to study how things move and the creation of computer graphics representations that look “good enough” Rendering is: mapping light sources and surfaces to a vector of pixel colors Animation is: mapping objects, intentions, and external forces to a vector of new object positions / orientations

We will not Develop drawing skills • but we may study how others draw so we can automate the process Learn how to use Maya • but we may use Maya as a rendering tool Hone our video game or moviemaking skills • but we will study how modern animation technology contributes to video games and what elements of moviemaking artistry (timing, camera angles, etc. ) must reside in animation tools

Study how things move Who else does this? • Biomechanists – Physics and sensors • Artists – Intuition and mind’s eye

Study how things move We’ll investigate • Human walking, running, dancing • Bicycle riding • Group behaviors • Rigid body dynamics

Generate graphics that is “good enough” Who else studies this? Monet La Cathédrale de Rouen (1894) • Perceptual psychologists • Artists University of Utah Picasso The Bull (1946)

Generate graphics that is “good enough” We’ll investigate • Recent perceptual literature (change blindness) • Recent computer animation experiments (faking physics)

Completing the mapping Bridge gap between knowledge of how things move to how they need to be rendered • Artists use their minds and hands • Computer scientists use math and programs

Traditional techniques • Keyframing (Shoemake) – Orientation reps (quaternion, euler) – Curve reps (linear, quadratic, wavelets) – Interpolation (computing arclength, Gaussian Quadrature, SLERP) • Disney artists (Johnson) • Timing / storyboarding

Numerical Methods • Curve fitting (least squares) • Optimization – Simulated annealing (Numerical Recipes) – Simplex – Spacetime Constraints (Witkin & Kass) – Genetic Algorithms (Sims) – Neural Networks (Grzeszczuk)

Human Motion • Motion Capture – Retargeting (Gleicher, J. Lee, Z. Popovic, Arikan) – Blending (Rose) – Abstraction (Unuma) • Walking – Biomechanics (Mc. Mahon, Ruina) – Gait Generation (Metaxas, van de Panne, Hodgins)

Physical Simulation • Rigid Body – Physics for games (Hecker) – Featherstone’s Method – Constraint satisfaction • Integration – Runge-Kutta – Euler • Simplification (Chenney, Lin, Popovic) • Perception (O’Sullivan, Proffitt)

Autonomous Agents • Behaviors (Thalmann, Badler, Blumberg) • Group actions (Reynolds, Brogan, Helbing)

Perception Positive afterimage (persistence of vision) • the visual stimulus that remains after illumination has changed or been removed Motion blur • Persistence of vision causes an object to appear to be multiple places at once

Motion Blur Virtual camera in computer graphics usually shoots with infinitely small shutter speed • No motion blur results Without motion blur, 30 fps results in fast moving objects that look like they are strobing, or hopping

What’s the rate? Playback rate • The number of samples displayed per second Sample rate • The number of different images per second Playback Rate Sample Rate TV Cartoon 30 6 TV Sitcom 30 30 (on fields) CG Lipsync on film 24 12

Perception Computer graphics rendering can rely on fourhundred years of perception research by artists • The best animators have is eighty years of Disney In 1550, after 100 years of refining the art of perspective drawing, artists were shocked to think that the geometric purity of their modeled world didn’t map to recent discoveries of the human eye. They couldn’t even imagine how cognition affected what one “saw. ” 200 more years would pass.

Animation timeline Persistence of vision • Thaumotrope (1800 s) • Flipbook • Zoetrope (1834) • Shadow puppets pbs. Kids

Animation timeline Photography • Muybridge (1885) • Film projector (Edison, 1891)

Animation Timeline First Animation • 1896, Georges Melies, moving tables • 1900, J. Stuart Blackton, added smoke First celebrated cartoonist • Winsor Mc. Cay • Little Nemo (1911) • Gertie the Dinosaur (1914)

Animation Timeline 1910, Bray and Hurd • Patented translucent cels (formerly celluloid was used, but acetate is used now) used in layers for compositing • Patented gray-scale drawings (cool!) • Patented using pegs for registration (alignment) of overlays • Patented the use of large background drawings and panning camera

Bray’s Studio Produced Max Fleischer – Betty Boop Paul Terry – Terrytoons George Stallings – Tom and Jerry Walter Lantz – Woody Woodpecker 1915, Fleischer patented rotoscoping • Drawing images on cells by tracing over previously recorded live action (Mo. Cap) 1920, color cartoons

Disney Advanced animation more than anyone else • First to have sound in 1928, Steamboat Willie • First to use storyboards • First to attempt realism • Invented multiplane camera

Multiplane Camera is mounted above multiple planes Each plane holds an animation cel Each plane can translate freely on 3 axes What is this good for? Zooming, moving foreground characters off camera, parallax, prolonged shutter allows blurring some layers (motion blur)

Stop-motion Animation Willis O’Brien – King Kong Ray Harryhausen – Mighty Joe Young Nick Park – Wallace and Grommit Tim Burton – Nightmare Before Christmas

Animation Heritage • 1963 – Ivan Sutherland’s (MIT) Sketchpad • 1970 – Evans and Sutherland (Utah) start computer graphics program (and Co. ) • 1972 – Ed Catmull’s (Utah) animated hand face (later co-founded Pixar) • 1970’s – Norm Badler (Penn) Center for Modeling and Simulation and Jack

Animation Heritage • 1970’s – New York Institute of Technology (NYIT) produced Alvy Ray Smith (Cofounded Pixar and Lucasfilm) and Catmull • 1980’s – Daniel and Nadia Magnenant. Thalmann (Swiss Universities) become European powerhouses

Animation Heritage • 1980’s – z-buffer invented, SGI founded, and Alias/Wavefront founded • 1977 – Starwars • 1982 – Tron (first extensive use of gfx) • 1982 – Early use of particle systems (Star Trek II: The Wrath of Khan) • 1984 – The Last Starfighter (look for the Cray XMP in credits)

Animation Heritage • 1986 – Young Sherlock Homes (first use of synthetic character in film) • 1986 – First digital wire removal (Howard the Duck) • 1988 – First digital blue screen extraction (Willow) • The Abyss (1989) Terminator II (1991) Casper (1995), Men in Black (1997)

Animation Heritage • ILM: Jurassic Park (1993), Jumangi (1995), Mars Attacks (1996), Flubber (1997), Titanic (1999) • Angel Studios: Lawnmower Man (1992) • PDI: Batman Returns (1995) • Tippett Studio: Dragonheart (1996), Starship Troopers (1997) • Disney: Beauty and the Beast (1991), Lion King (1994), Tarzan (1999) • Dreamworks: Antz, Prince of Egypt • Pixar: Toy Story, A Bug’s Life, Monster’s Inc.

Americans are hardest working Recent history United Nations report from Sept 1, 2003 • $/worker-year – US = $60, 728, Belgium (top EU) = $54, 333 • hours/worker-year – US = Japan = 1825, EU = 1300 – 1800 • $/worker-hour – Norway, France, Belgium, US $38 $35 $34 $32 • Why is US on top of $/worker-year? – Best economies encourage widespread use of communications and information technology – Even though we’re fat, dumb, and happy – we don’t take month-long vacations and one-year maternity breaks

Let’s talk about computer animation Must generate 30 frames per second of animation (24 fps for film) Issues to consider: • Is the goal to replace or augment the artist? – What does the artist bring to the project? • Is the scene/plot fixed or responsive to user? – What can we automate?

Animation – A broad Brush Traditional Methods • Cartoons, stop motion Keyframing • Digital inbetweens Motion Capture • What you record is what you get Simulation • Animate what you can model (with equations)

Computer Animation

Keyframing Traditional animation technique Dependent on artist to generate ‘key’ frames Additional, ‘inbetween’ frames are drawn automatically by computer

Keyframing How are we going to interpolate? From “The computer in the visual arts”, Spalter, 1999

Linear Interpolation Simple, but discontinuous velocity

Nonlinear Interpolation Smooth ball trajectory and continuous velocity, but loss of timing

Easing Adjust the timing of the inbetween frames. Can be automated by adjusting the stepsize of parameter, t.

Style or Accuracy? Interpolating time captures accuracy of velocity Squash and stretch replaces motion blur stimuli and adds life-like intent

Traditional Motivation Ease-in and ease-out is like squash and stretch Can we automate the inbetweens for these? “The Illusion of Life, Disney Animation” Thomas and Johnson

More squash and stretch

Anticipation and Staging Don’t surprise the audience Direct their attention to what’s important

Follow Through Audience likes to see resolution of action Discontinuities are unsettling

Combined

Secondary Motion Characters should exist in a real environment Extra movements should not detract

Interpolation Many parameters can be interpolated to generate animation Simple interpolation techniques can only generate simple inbetweens More complicated inbetweening will require a more complicated model of animated object and simulation

Interpolation Strengths • Animator has exacting control (Woody’s face) Weaknesses • Interpolation hooks must be simple and direct – Remember the problems with Euler angle interp? • Time consuming and skill intensive • Difficult to reuse and adjust

Examples Sports video games • Madden Football Many movie characters • Phantom Menace Cartoons

Motion Capture Strengths Exactly captures the motions of the actor • Michael Jordan’s video game character will capture his style Easy to capture data

Motion Capture Weaknesses Noise, noise! Magnetic system inteference Visual system occlusions Mechanical system mass Tethered (wireless is available now)

Motion Capture Weaknesses Aligning motion data with CG character • Limb lengths • Idealized perfect joints • Foot sliding Reusing motion data • Difficult to scale in size (must also scale in time) • Changing one part of motion

Motion Capture Weaknesses Blending segments • Motion clips are short (due to range and tethers) • Dynamic motion generation requires blending at run time • Difficult to manage smooth transition

Procedural http: //jet. ro/dismount www. sodaplay. com

Examples Inanimate video game objects • GT Racer cars • Soapbox about why this is so cool Special effects • Explosions, water, secondary motion • Phantom Menace CG droids after they were cut in half

Procedural Animation Very general term for a technique that puts more complex algorithms behind the scenes Technique attempts to consolidate artistic efforts in algorithms and heuristics Allows for optimization and physical simulation

Procedural Animation Strengths Animation can be generated ‘on the fly’ Dynamic response to user Write-once, use-often Algorithms provide accuracy and exhaustive search that animators cannot

Procedural Animation Weaknesses We’re not great at boiling human skill down to algorithms • How do we move when juggling? Difficult to generate Expensive to compute Difficult to force system to generate a particular solution • Bicycles will fall down

Fundamental Animation Techniques

Fundamental Animation Techniques Squash and Stretch Timing Anticipation Staging Slow In and Slow Out Arcs Exaggeration Secondary Action Appeal Personality

Squash and Stretch

More squash and stretch

Timing – is everything!

Timing = speed of action Relays the idea behind the action Too fast: • might notice at all • Might not understand what’s happened • might not pay enough attention Too slow: • Sense of action can be lost • can become boring

Timing Defines weight of the object • Heavy objects accelerate slowly • Size in general should correspond to the mass Shows emotional state Identical key frames can have different timing

Timing example Two key frames • Head leaning toward the right shoulder • Head over left shoulder, chin slightly raised Vary the number of in-between frames, 0 to 10 Very different ideas can be communicated

Timing example, cont. 0: hit by tremendous force 1: hit by a brick, frying pan 2: nervous tick, muscle spasm 3: dodging a brick, frying pan 4: giving a crisp order “Move it !” 5: friendly “Over here. Come on - hurry” 6: sees a sports car he always wanted 7: tries to get a better look at something. 8: searches for a book on a shelf 9: appraises, considering thoughtfully 10: stretches a sore muscle Example from: Thomas and Johnson “Disney animation – the illusion of life”

Anticipation

Anticipation Action has three parts • Preparation for the action (anticipation) • Action itself • Termination of the action (follow through) Need anticipation to: • Make actions natural – Muscle movement (kicking a ball) • Prepare audience for the following action • Direct attention to another part of the screen

Anticipation Slow action: can use little anticipation • Meaning is carried by the action itself Fast action: need more anticipation • Need to know what’s going to happen even before the action Exaggerated anticipation: • Emphasize extreme weight / action difficulty

Staging

Follow-Thru and Overlapping Action

Follow through Actions rarely come to sudden stops There are leading parts, other participating parts and appendages Action starts by leading part Main action follows Appendages continue to move longer • Heavy ones drag alonger

Follow Through Audience likes to see resolution of action Discontinuities are unsettling

Overlapping action Add variations to timing of loose parts • Little extra actions make it more interesting New action starts BEFORE previous one stops • Full stops are rare locking open door: • Start walking to the door • Before coming to the door, reach for the door • Before completely closing, reach for the key, etc.

Slow in and slow out Even spacing between frames = constant speed Better to have gradual acceleration and slowing down

Bouncing Ball Example The ball on the left moves at a constant speed with no squash/stretch. The ball in the center does slow in and out with a squash/stretch. The ball on the right moves at a constant speed with

Arcs Visual path should be an arc • Rather than a straight line

Exaggeration and secondary action Keep it balanced Have some natural elements and some exaggerated ones Secondary action – results directly from primary action • Gives natural complexity • Can be missed if happens in the middle of major move Should be obvious but kept secondary The secondary action of Luxo Jr's forward motion is the rippling of his power cord.

Exaggeration

Secondary Action

Appeal & Personality

Basic Camera Shots Wide Shot/Establishing Shot/Long Shot Medium Shot Close Up Shot Cutaway Shot/Over the Shoulder Two Shot/Three Shot Sequence Length of shot

Wide Shot/Establishing

Medium Shot

Close Up Shot

Extreme Close Up

Two Shot/Three Shot

Cutaway Shot Cutaway (CA) cutaway is a shot that's usually of something other than the current action. It could be a different subject (eg. this cat when the main subject is its owner), a close up of a different part of the subject (eg. the subject's hands), or just about anything else. The cutaway is used as a "buffer" between shots (to help the editing process), or to add interest/information. A

Basic Camera Moves Zoom In Zoom Out Pan Right, Pan Left Action in the frame. Follow the action/rolling shot.

Standard Movie Openings Movie Opening 1 Movie Opening 2 Wide Shot Tight Close-Up Zoom to Medium Out to Medium Some Action Zoom to close-up Out to Medium Most Bond Films Run with it. Raiders of Lost Ark