Computer AnimationJason LawrenceCS445: GraphicsAcknowledgment: slides by Misha Kazhdan, Allison Klein, Tom Funkhouser,Adam Finkelstein and David DobkinOverview• Some early animation historyohttp://web.inter.nl.net/users/anima/index.htmohttp://www.public.iastate.edu/~rllew/chrnearl.html• Computer animationThaumatrope• Why does animation work?• Persistence of vision• 1824 John Ayerton invents the thaumatrope • Or, 1828 Paul Roget invents the thaumatropeThaumatrope• Why does animation work?• Persistence of vision• 1824 John Ayerton invents the thaumatrope • Or, 1828 Paul Roget invents the thaumatropePhenakistoscope • Invented independently by 2 people in 1832• Disc mounted on spindle• Viewed through slots with images facing mirror• Turning disc animates imagesPhenakistoscope • Invented independently by 2 people in 1832• Disc mounted on spindle• Viewed through slots with images facing mirror• Turning disc animates imagesPhenakistoscope • Invented independently by 2 people in 1832• Disc mounted on spindle• Turning disc animates images • Viewed through slots with images facing mirrorZoetrope (1834)• Images arranged on paper band inside a drum• Slits cut in the upper half of the drum• Opposite side viewed as drum rapidly spun• Praxinoscope is a variation on thisZoetrope (1834)• Images arranged on paper band inside a drum• Slits cut in the upper half of the drum• Opposite side viewed as drum rapidly spun• Praxinoscope is a variation on thisMutoscope (1895)• Coin-operated “flip-book” animation• Picture cards attached to a drum• Popular at sea-side resorts, etc.Animation History• Animation and technology have always gone together!• Animation popular even before movies• Movies were big step forward!• “Humorous Phases of Funny Faces” (1906)Key Developments• Plot• Creation of animation studios• Getting rid of “rubber-hose” bodies• Inking on cels“Gertie the Dinosaur”Windsor McCay (1914)“Felix the Cat”Otto Messmer (1921)“Steamboat Willie”Walt Disney (1928)Key Developments• Max Fleischer invents rotoscoping (1921)Key Developments• Max Fleischer invents rotoscoping (1921)Key Developments• “Flowers and Trees” (1932) uses color!• “Snow White” (aka “Disney’s Folly”) released 1937“Flowers and Trees”Walt Disney“Snow White”Walt DisneyAnimation Uses• Entertainment• Education• War propagandaOverview• Some early animation historyohttp://web.inter.nl.net/users/anima/index.htmohttp://www.public.iastate.edu/~rllew/chrnearl.html• Computer animationComputer Animation• What is animation?oMake objects change over time according to scripted actions• What is simulation?oPredict how objects change over timeaccording to physical lawsUniversity of IllinoisPixar3-D and 2-D animationHomer 3-D Homer 2-DOutline• Principles of animation• Keyframe animation• Articulated figures Angel Plate 1Principles of Traditional Animation• Squash and Stretch• Timing• Anticipation• Staging• Follow Through and Overlapping Action• Straight Ahead Action and Pose-to-Pose Action• Slow In and Out• Arcs• Exaggeration• Secondary action• Appealhttp://www.anticipation.info/texte/lasseter/principles.htmlLuxo JuniorPrinciples of Traditional AnimationSquash and Stretch• Defining the rigidity and mass of an object by distorting its shape during an action.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationTiming• Spacing actions to define the weight and size of objects and the personality of characters.oHeavier objects accelerate sloweroLethargic characters move sloweroEtc.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationAnticipation• The preparation for an action.oMuscle contraction prior to extensionoBending over to lift a heavy objectoLuxo’s dad responds to Luxo Jr. off screen before Luxo Jr. appears.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationStaging• Presenting an idea so that it is unmistakably clear.oKeeping the viewer’s attention focused on a specific part of the scene.oLuxo Jr. moves faster than his dad, and so we focus on him.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationFollow Through and Overlapping Action• The termination of an action and establishing its relationship to the next action.oLoose clothing will “drag” and continue moving after the character has stopped moving.oThe way in which an object slows down indicates its weight/mood.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationStraight Ahead Action and Pose-to-Pose Action• The two contrasting approaches to the creation of movement.oStraight Ahead Action:» Action is drawn from the first frame through to the last one.» Wild, scrambling actions where spontaneity is important. oPose-to-Pose Action:» Poses are pre-conceived and animator fills in the in-betweens.» Good acting, where the poses and timing are all important. http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationSlow In and Out• The spacing of in-between frames to achieve subtlety of timing and movements.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationArcs• The visual path of action for natural movement.oMake animation much smoother and less stiff than a straight line for the path of action http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationExaggeration• Accentuating the essence of an idea via the design and the action.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationSecondary Action• The Action of an object resulting from another action.oThe rippling of Luxo Jr.’s cord as he bounces around the scene.http://www.anticipation.info/texte/lasseter/principles.htmlPrinciples of Traditional AnimationAppeal• Creating a design or an action that the audience enjoys watching.oCharm oPleasing design oSimplicity oCommunicationoMagnetismoEtc.http://www.anticipation.info/texte/lasseter/principles.htmlKeyframe Animation• Define character poses at specific time stepscalled “keyframes”Lasseter `87Keyframe Animation• Interpolate variables describing keyframes to determine poses for character “in-between”Lasseter
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