CS-184: Computer Graphics Lecture #15: Introduction to Animation - - PowerPoint PPT Presentation

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CS-184: Computer Graphics Lecture #15: Introduction to Animation - - PowerPoint PPT Presentation

Oct 31, 2022 209 likes •390 views

CS-184: Computer Graphics Lecture #15: Introduction to Animation Prof. James OBrien University of California, Berkeley V2016-F-15-1.0 Introduction to Animation Generate perception of motion with sequence of image shown in rapid

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SLIDE 1

CS-184: Computer Graphics

Lecture #15: Introduction to Animation

  • Prof. James O’Brien

University of California, Berkeley

V2016-F-15-1.0

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Introduction to Animation

  • Generate perception of motion with sequence of image

shown in rapid succession

  • Real-time generation (e.g. video game)
  • Off-line generation (e.g. movie or television)

15-AnimationIntro.key - November 9, 2016

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SLIDE 2

Some History

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(Phenakistoscope, 1831)

Some History

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Edward Muybridge, “Sallie Gardner” (1878)

15-AnimationIntro.key - November 9, 2016

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SLIDE 3

Some History

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Disney, “Snow White and the Seven Dwarfs” (1937)

Some History

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Ivan Sutherland, “Sketchpad” (1963) – Light pen, vector display

15-AnimationIntro.key - November 9, 2016

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SLIDE 4

Some History

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Ed Catmull & Frederick Parke, “Computer Animated Faces” (1972)

Some History

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Jurassic Park (1993)

15-AnimationIntro.key - November 9, 2016

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SLIDE 5

Some History

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Pixar, “Toy Story” (1995)

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Introduction to Animation

  • Key technical problem is how to generate and manipulate

motion

  • Human motion
  • Inanimate objects
  • Amorphous objects
  • Control

15-AnimationIntro.key - November 9, 2016

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SLIDE 6

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Introduction to Animation

  • Technical issues often dominated by aesthetic ones
  • Violation of realism desirable in some contexts
  • Animation is a communication tool
  • Should support desired communication
  • There should be something to communicate

12 Animation Principles

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1. Squash and stretch 2. Anticipation 3. Staging 4. Straight ahead and pose-to-pose 5. Follow through and overlapping 6. Slow in and slow out 7. Arcs 8. Secondary action 9. Timing 10. Exaggeration 11. Solid drawings 12. Appeal

15-AnimationIntro.key - November 9, 2016

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SLIDE 7

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Introduction to Animation

  • Key-frame animation
  • Specification by hand
  • Motion capture
  • Recording motion
  • Procedural / simulation
  • Automatically generated
  • Combinations
  • e.g. mocap + simulation

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Key-framing (manual)

Keyframes “Tweens”

15-AnimationIntro.key - November 9, 2016

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SLIDE 8

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Key-framing (manual)

  • Requires a highly skilled user
  • Poorly suited for interactive applications
  • High quality / high expense
  • Limited applicability

From Learning Maya 2.0

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Key-framing (manual)

Hearn, Baker and Carithers, Figure 16.11

15-AnimationIntro.key - November 9, 2016

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SLIDE 9

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Key-framing (manual)

Linear interpolation usually not good enough Recall splines for smooth / controllable interpolation

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Motion Capture (recorded)

  • Markers/sensors placed on subject
  • Time-consuming clean-up
  • Reasonable quality / reasonable price
  • Manipulation algorithms an active research area

MotionAnalysis / Performance Capture Studio Okan Arikan

15-AnimationIntro.key - November 9, 2016

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SLIDE 10

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Motion Editing

Arikan, Forsyth, O’Brien, SIGGRAPH 2002

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Motion Editing

Arikan, Forsyth, O’Brien, SIGGRAPH 2002

15-AnimationIntro.key - November 9, 2016

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SLIDE 11

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Model Construction

Kirk, O’Brien, Forsyth, CVPR 2005

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Simulation

  • Generate motion of objects using numerical simulation

methods

xt+∆t = xt +∆t vt + 1 2∆t2at

g

v

15-AnimationIntro.key - November 9, 2016

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SLIDE 12

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Simulation

  • Perceptual accuracy required
  • Stability, easy of use, speed, robustness all important
  • Predictive accuracy less so
  • Control desirable

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Simulation

Feldman, Arikan, O’Brien, SIGGRAPH 2003

15-AnimationIntro.key - November 9, 2016

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SLIDE 13

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Digital Video

  • Wide range of file formats
  • QuickTime
  • MS Audio/Visual Interleaved (AVI)
  • DV Stream
  • Bunch ‘o images
  • Some formats accommodate different CODECs
  • Quicktime: Cinepak, DV, Sorenson, DivX, etc.
  • AVI: Cinepak, Indeo, DV, MPEG4, etc.
  • Some formats imply a given CODEC
  • MPEG
  • DV Streams

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Digital Video

  • Nearly all CODECs are lossy
  • Parameter setting important
  • Different type of video work with different CODECs
  • Compressors not all equally smart
  • Compression artifacts are cumulative in a very bad way
  • Playback issues
  • Bandwidth and CPU limitations
  • Hardware acceleration
  • Missing CODECs (avoid MS CODECs and formats)

15-AnimationIntro.key - November 9, 2016

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SLIDE 14

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Editing

  • Old way:
  • Multiple expensive tape decks
  • Slow
  • Difficult
  • Error prone
  • New way:
  • Non-linear editing software
  • Premiere, Final Cut Pro, others...
  • Beware compressed solutions
  • May take a long time for final encoding

Interactive Animation

  • Video Games

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15-AnimationIntro.key - November 9, 2016

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SLIDE 15

Interactive Animation

  • “Serious” Games

29 30

Motion Blur

  • Fast moving things look blurry
  • Human eye
  • Finite exposure time in cameras
  • Without blur: strobing and aliasing
  • Blur over part of frame interval
  • Measured in degrees (0..360)
  • 30 tends to often look good

15-AnimationIntro.key - November 9, 2016

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SLIDE 16

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Motion Blur

  • Easy to do in a sampling framework
  • Interpolation is an issue

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Motion Blur

Brave 2012 15-AnimationIntro.key - November 9, 2016

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SLIDE 17

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Motion Blur

  • Velocity based blur often works poorly

15-AnimationIntro.key - November 9, 2016