Animation CS 551 / 651 Lecture 2 Introduction Introduction.
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Transcript of Animation CS 551 / 651 Lecture 2 Introduction Introduction.
AnimationCS 551 / 651
Lecture 2Lecture 2
IntroductionIntroduction
Lecture 2Lecture 2
IntroductionIntroduction
Today’s News: Americans are hardest working!
United Nations report from Sept 1, 2003United Nations report from Sept 1, 2003
• $/worker: US = $60,728, Belgium (top EU) = $54,333$/worker: US = $60,728, Belgium (top EU) = $54,333
• hours/worker: US = Japan = 1825, EU = 1300 – 1800hours/worker: US = Japan = 1825, EU = 1300 – 1800
• output/worker-hour: Norway, France, Belgium, USoutput/worker-hour: Norway, France, Belgium, US $38 $35 $34 $32 $38 $35 $34 $32
• Why is US on top of $/worker?Why is US on top of $/worker?
– US economy encourages widespread use of US economy encourages widespread use of communications and information technology communications and information technology
United Nations report from Sept 1, 2003United Nations report from Sept 1, 2003
• $/worker: US = $60,728, Belgium (top EU) = $54,333$/worker: US = $60,728, Belgium (top EU) = $54,333
• hours/worker: US = Japan = 1825, EU = 1300 – 1800hours/worker: US = Japan = 1825, EU = 1300 – 1800
• output/worker-hour: Norway, France, Belgium, USoutput/worker-hour: Norway, France, Belgium, US $38 $35 $34 $32 $38 $35 $34 $32
• Why is US on top of $/worker?Why is US on top of $/worker?
– US economy encourages widespread use of US economy encourages widespread use of communications and information technology communications and information technology
Let’s talk about computer animation
Must generate 30 frames per second of Must generate 30 frames per second of animation (24 fps for film)animation (24 fps for film)
Issues to consider:Issues to consider:
• Is the goal to replace or augment the artist?Is the goal to replace or augment the artist?
– What does the artist bring to the project?What does the artist bring to the project?
• Is the scene/plot fixed or responsive to user?Is the scene/plot fixed or responsive to user?
– What can we automate?What can we automate?
Must generate 30 frames per second of Must generate 30 frames per second of animation (24 fps for film)animation (24 fps for film)
Issues to consider:Issues to consider:
• Is the goal to replace or augment the artist?Is the goal to replace or augment the artist?
– What does the artist bring to the project?What does the artist bring to the project?
• Is the scene/plot fixed or responsive to user?Is the scene/plot fixed or responsive to user?
– What can we automate?What can we automate?
Animation – A broad Brush
Traditional MethodsTraditional Methods
• Cartoons, stop motionCartoons, stop motion
KeyframingKeyframing
• Digital inbetweensDigital inbetweens
Motion CaptureMotion Capture
• What you record is what you getWhat you record is what you get
SimulationSimulation
• Animate what you can model (with equations)Animate what you can model (with equations)
Traditional MethodsTraditional Methods
• Cartoons, stop motionCartoons, stop motion
KeyframingKeyframing
• Digital inbetweensDigital inbetweens
Motion CaptureMotion Capture
• What you record is what you getWhat you record is what you get
SimulationSimulation
• Animate what you can model (with equations)Animate what you can model (with equations)
Computer Animation
Keyframing
Traditional animation techniqueTraditional animation technique
Dependent on artist to generate ‘key’ Dependent on artist to generate ‘key’ framesframes
Additional, ‘inbetween’ frames are drawn Additional, ‘inbetween’ frames are drawn automatically by computerautomatically by computer
Traditional animation techniqueTraditional animation technique
Dependent on artist to generate ‘key’ Dependent on artist to generate ‘key’ framesframes
Additional, ‘inbetween’ frames are drawn Additional, ‘inbetween’ frames are drawn automatically by computerautomatically by computer
Keyframing
From “The computer in the visual arts”, Spalter, 1999
How are we going to interpolate?
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 timeInterpolating timecaptures accuracycaptures accuracyof velocityof velocity
Squash and stretchSquash and stretchreplaces motionreplaces motionblur stimuli andblur stimuli andadds life-likeadds life-likeintentintent
Interpolating timeInterpolating timecaptures accuracycaptures accuracyof velocityof velocity
Squash and stretchSquash and stretchreplaces motionreplaces motionblur stimuli andblur stimuli andadds life-likeadds life-likeintentintent
Traditional Motivation
Ease-in andEase-in andease-out is likeease-out is likesquash andsquash andstretchstretch
Can weCan weautomate theautomate theinbetweens forinbetweens forthese?these?
Ease-in andEase-in andease-out is likeease-out is likesquash andsquash andstretchstretch
Can weCan weautomate theautomate theinbetweens forinbetweens forthese?these?
“The Illusion of Life, Disney Animation”Thomas and Johnson
More squash and stretch
Anticipation and Staging
Don’t surprise theDon’t surprise theaudienceaudience
Direct their Direct their attention to what’sattention to what’simportantimportant
Don’t surprise theDon’t surprise theaudienceaudience
Direct their Direct their attention to what’sattention to what’simportantimportant
Follow Through
Audience likes to see resolution of actionAudience likes to see resolution of action
Discontinuities are unsettlingDiscontinuities are unsettling
Audience likes to see resolution of actionAudience likes to see resolution of action
Discontinuities are unsettlingDiscontinuities are unsettling
Combined
Secondary Motion
Characters should exist in a real Characters should exist in a real environmentenvironment
Extra movements should not detractExtra movements should not detract
Characters should exist in a real Characters should exist in a real environmentenvironment
Extra movements should not detractExtra movements should not detract
Interpolation
Many parameters can be interpolated to Many parameters can be interpolated to generate animationgenerate animation
Simple interpolation techniques can only Simple interpolation techniques can only generate simple inbetweensgenerate simple inbetweens
More complicated inbetweening will require More complicated inbetweening will require a more complicated model of animated a more complicated model of animated object and simulationobject and simulation
Many parameters can be interpolated to Many parameters can be interpolated to generate animationgenerate animation
Simple interpolation techniques can only Simple interpolation techniques can only generate simple inbetweensgenerate simple inbetweens
More complicated inbetweening will require More complicated inbetweening will require a more complicated model of animated a more complicated model of animated object and simulationobject and simulation
Interpolation
StrengthsStrengths
• Animator has exacting control (Woody’s face)Animator has exacting control (Woody’s face)
WeaknessesWeaknesses
• Interpolation hooks must be simple and directInterpolation hooks must be simple and direct
– Remember the problems with Euler angle interp?Remember the problems with Euler angle interp?
• Time consuming and skill intensiveTime consuming and skill intensive
• Difficult to reuse and adjustDifficult to reuse and adjust
StrengthsStrengths
• Animator has exacting control (Woody’s face)Animator has exacting control (Woody’s face)
WeaknessesWeaknesses
• Interpolation hooks must be simple and directInterpolation hooks must be simple and direct
– Remember the problems with Euler angle interp?Remember the problems with Euler angle interp?
• Time consuming and skill intensiveTime consuming and skill intensive
• Difficult to reuse and adjustDifficult to reuse and adjust
Examples
Sports video gamesSports video games
• Madden FootballMadden Football
Many movie charactersMany movie characters
• Phantom MenacePhantom Menace
CartoonsCartoons
Sports video gamesSports video games
• Madden FootballMadden Football
Many movie charactersMany movie characters
• Phantom MenacePhantom Menace
CartoonsCartoons
Motion Capture Strengths
Exactly captures the motions of the actorExactly captures the motions of the actor
• Michael Jordan’s video game character will capture Michael Jordan’s video game character will capture his stylehis style
Easy to capture dataEasy to capture data
Exactly captures the motions of the actorExactly captures the motions of the actor
• Michael Jordan’s video game character will capture Michael Jordan’s video game character will capture his stylehis style
Easy to capture dataEasy to capture data
Motion Capture Weaknesses
Noise, noise, noise!Noise, noise, noise!
Magnetic system inteferenceMagnetic system inteference
Visual system occlusionsVisual system occlusions
Mechanical system massMechanical system mass
Tethered (wireless is available now)Tethered (wireless is available now)
Noise, noise, noise!Noise, noise, noise!
Magnetic system inteferenceMagnetic system inteference
Visual system occlusionsVisual system occlusions
Mechanical system massMechanical system mass
Tethered (wireless is available now)Tethered (wireless is available now)
Motion Capture Weaknesses
Aligning motion data with CG characterAligning motion data with CG character
• Limb lengthsLimb lengths
• Idealized perfect jointsIdealized perfect joints
Reusing motion dataReusing motion data
• Difficult to scale in size (must also scale in time)Difficult to scale in size (must also scale in time)
• Changing one part of motionChanging one part of motion
Aligning motion data with CG characterAligning motion data with CG character
• Limb lengthsLimb lengths
• Idealized perfect jointsIdealized perfect joints
Reusing motion dataReusing motion data
• Difficult to scale in size (must also scale in time)Difficult to scale in size (must also scale in time)
• Changing one part of motionChanging one part of motion
Motion Capture Weaknesses
Blending segmentsBlending segments
• Motion clips are short (due to range and tethers)Motion clips are short (due to range and tethers)
• Dynamic motion generation requires blending at Dynamic motion generation requires blending at run timerun time
• Difficult to manage smooth transitionDifficult to manage smooth transition
Blending segmentsBlending segments
• Motion clips are short (due to range and tethers)Motion clips are short (due to range and tethers)
• Dynamic motion generation requires blending at Dynamic motion generation requires blending at run timerun time
• Difficult to manage smooth transitionDifficult to manage smooth transition
Examples
Inanimate video game objectsInanimate video game objects
• GT Racer carsGT Racer cars
• Soapbox about why this is so coolSoapbox about why this is so cool
Special effectsSpecial effects
• Explosions, water, secondary motionExplosions, water, secondary motion
• Phantom Menace CG droids after they were cut in Phantom Menace CG droids after they were cut in halfhalf
Inanimate video game objectsInanimate video game objects
• GT Racer carsGT Racer cars
• Soapbox about why this is so coolSoapbox about why this is so cool
Special effectsSpecial effects
• Explosions, water, secondary motionExplosions, water, secondary motion
• Phantom Menace CG droids after they were cut in Phantom Menace CG droids after they were cut in halfhalf
Procedural Animation
Very general term for a technique that puts Very general term for a technique that puts more complex algorithms behind the more complex algorithms behind the scenesscenes
Technique attempts to consolidate artistic Technique attempts to consolidate artistic efforts in algorithms and heuristicsefforts in algorithms and heuristics
Allows for optimization and physical Allows for optimization and physical simulationsimulation
Very general term for a technique that puts Very general term for a technique that puts more complex algorithms behind the more complex algorithms behind the scenesscenes
Technique attempts to consolidate artistic Technique attempts to consolidate artistic efforts in algorithms and heuristicsefforts in algorithms and heuristics
Allows for optimization and physical Allows for optimization and physical simulationsimulation
Procedural Animation Strengths
Animation can be generated ‘on the fly’Animation can be generated ‘on the fly’
Dynamic response to userDynamic response to user
Write-once, use-oftenWrite-once, use-often
Algorithms provide accuracy and exhaustive Algorithms provide accuracy and exhaustive search that animators cannotsearch that animators cannot
Animation can be generated ‘on the fly’Animation can be generated ‘on the fly’
Dynamic response to userDynamic response to user
Write-once, use-oftenWrite-once, use-often
Algorithms provide accuracy and exhaustive Algorithms provide accuracy and exhaustive search that animators cannotsearch that animators cannot
Procedural Animation Weaknesses
We’re not great at boiling human skill down We’re not great at boiling human skill down to algorithmsto algorithms• How do we move when juggling?How do we move when juggling?
Difficult to generateDifficult to generate
Expensive to computeExpensive to compute
Difficult to force system to generate a Difficult to force system to generate a particular solutionparticular solution• Bicycles will fall downBicycles will fall down
We’re not great at boiling human skill down We’re not great at boiling human skill down to algorithmsto algorithms• How do we move when juggling?How do we move when juggling?
Difficult to generateDifficult to generate
Expensive to computeExpensive to compute
Difficult to force system to generate a Difficult to force system to generate a particular solutionparticular solution• Bicycles will fall downBicycles will fall down
Homework
For next week:For next week:
• Read Chris Hecker articles (all four in series) on Read Chris Hecker articles (all four in series) on physical simulationphysical simulation
Game Developer MagazineGame Developer MagazineOctober/November 1996October/November 1996
• http://www.d6.com/users/checker/pdfs/gdmphys[1-4].pdfhttp://www.d6.com/users/checker/pdfs/gdmphys[1-4].pdf
For next week:For next week:
• Read Chris Hecker articles (all four in series) on Read Chris Hecker articles (all four in series) on physical simulationphysical simulation
Game Developer MagazineGame Developer MagazineOctober/November 1996October/November 1996
• http://www.d6.com/users/checker/pdfs/gdmphys[1-4].pdfhttp://www.d6.com/users/checker/pdfs/gdmphys[1-4].pdf