TCSS491A Isabelle Bichindaritz

1
Principles of Computer Animation
2
Agenda

• What is computer animation?
• Some history
• Animation principles
• Animation development

3
Learning Objectives

• Understand what is computer animation.
• Understand the main principles of computer
  animation.

4
Acknowledgments

• References
• Lasseter, John. Principles of traditional
  animation applied to 3D computer animation.
  Proceedings of the 14th annual conference on
  Computer graphics and interactive techniques,
  198735 44.
• Lasseter, John. Tricks to animating characters
  with a computer. ACM SIGGRAPH Computer Graphics,
  Volume 35 ,  Issue 2, May 2001 45-47.
• Parent, Rick. Computer Animation. Morgan Kaufmann
  Publishers, San Francisco, CA, 2002.

5
What is Computer Animation?

• Computer animation refers to any time sequence of
  visual changes from a picture (H. Baker).
• The goal of character animation is to make
  characters that move in a convincing way to
  communicate personality and mood.

6
History of Computer Animation

• Animation started hand-drawn (conventional
  animation).
• First moving picture was designed for the camera
  by Georges Melies (1896) with camera tricks.
• Pioneers in the 19th century and early 20th
  century.
• First popular animations created by Winsor McCay
  Little Nemo (1911), Gertie the Dinosaur (1914).
  Was also a newspaper cartoonist.

7
History of Computer Animation

• First animation studio Bray and Hurl (1914)
  patented translucent cels to compose several
  layers of drawings into an image.
• Produced Max Fleischer (Betty Boop), Paul Terry
  (Terrytoons), George Stallings (Tom and Jerry),
  and Walter Lantz (Woody Woodpecker).
• Color was added in 1920.
• First famous personality was Felix the Cat
  (mid-1920s).
• Then came disney.

8
History of Computer Animation

• Walt Disney is the most prominent animator in the
  history of conventional animation. Created many
  innovations
• Adding sound (1928).
• Use of storyboards and pencil sketches.
• Multiplane camera, mounted above multiple planes
  containing an animation cell. Enhances parallax
  effect sensation of three dimensions.
• Promoted the idea that the mind of the character
  is the driving force of the action, and that the
  key to believable animated motion is the analysis
  of real-life motion.

9
History of Computer Animation

• Today, animations are not only used for different
  purposes
• In movies such as Star Wars, Toy Story, and
  Titanic to produce special effects or synthetic
  characters playing in the movie (Terminator II,
  Casper, Men in Black).
• 3D computer animations to replace 2D conventional
  animation such as Toy Story or enhance it such as
  in Beauty and the Beast.
• Desktop computer animation.
• Computer simulations.

10
Principles of Animation

• Principles of good animations are the same for
  traditional animation and computer animation.
• Good animation design tools do not ensure high
  quality animations (Maya, ).
• Follow principles learnt from hand drawn
  character animation for 50 years before computer
  animations such as 3D keyframe computer
  animations (systems generating in-betweens around
  user specified key frames).

11
Principles of Animation

• Principles of animation (from John Lasseter)
• Squash and stretch
• Timing
• Anticipation
• Staging
• Follow throughaction
• Overlapping action
• Straight ahead action and pose-to-pose action
• Slow in and out
• Arcs
• Exaggeration
• Secondary action
• Appeal

12
Principles of Animation

• Squash and stretch
• The most important principle.
• Refers to defining the rigidity and mass of an
  object by distorting its shape during an action.
• Shape of object changes during movement, but not
  its volume.
• Example drawing a bouncing ball.

13
Principles of Animation

• Squash and stretch
• Rigidity of objects is more prevalent than that
  of living things.
• Objects can change form in order to squash and
  stretch.

14
Principles of Animation

• Squash and stretch
• Used to alleviate strobing effect in fast
  action, objects positions do not overlap, which
  is perceived by the eye.

15
Principles of Animation

• Timing
• Refers to the speed of an action.
• Very important to balance between the need of the
  audience to follow the action (spend enough time)
  and not to feel bored (do not spend too much
  time).
• Timing to show
• Anticipation of action
• Action itself
• Reaction to action
• Weight of a character (heavy weight moves more
  slowly than light weight), effect of weight is
  dependant on spacing of the poses
• Emotional state of a character

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Principles of Animation

• Timing
• Two drawings of a head leaning over right
  shoulder then left shoulder have different
  meanings depending on the timing between these
  (number of images between them)
• NO inbetweens
• ONE inbetween
• TWO inbetweens
• THREE inbetweens
• FOUR inbetweens
• FIVE inbetweens
• SIX inbetweens
• SEVEN inbetweens

• Hit by huge force
• Hit by an object (brick)
• Nervous tic, spasm
• Dodging an object (brick)
• Giving crisp order (Go)
• Giving gentle order (Over here)
• Following an interesting sight
• Trying to look at something

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Principles of Animation

• Anticipation
• Action has three parts preparation, action
  itself, termination
• Anticipation refers to the preparation of an
  action
• Extension of muscles before action
• Catch the audience attention (before grabbing an
  object, characters looks at it and moves arm)
• Direct the attention of the audience toward the
  center of the action, influences the speed of the
  action, because anticipated action can go faster
• Emphasizes heavy weight (longer anticipation for
  lifting a heavy weight).

18
Principles of Animation

• Staging
• Refers to presently clearly an idea so that it is
  completely clear.
• Lead clearly the eye to where it should be.
• Audience can see only one thing at a time,
  therefore direct attention to one thing at a
  time.
• Action staged better in silhouette (should show
  in silhouette). Example scratch to a side and
  not to the front, characters talk ¾ facing the
  camera.

19
Principles of Animation

• Follow through
• Follow through refers to the termination of the
  action.
• Actions do not stop abruptly because actions take
  some time to answer the impulse to start them,
  and in the same way they take some time to
  complete.
• Action has a lead that initiates the movement,
  and appendages (loose parts) that follow.
  Appendages move after the lead, and also stop
  after it.
• Lighter appendages stop faster than heavier ones.
• Example throwing a ball, walking (lead hips
  swinging forward).

20
Principles of Animation

• Overlapping action and secondary action
• Refers to not bringing an action to a complete
  stop before starting the next action.
• Refers to intention behind an action.
• Walt Disney example Ill close the door, lock
  it, then Im going to undress and go to bed.

21
Principles of Animation

• Straight ahead action vs. pose-to-pose action
• Two approaches to hand drawn animation.
• Straight ahead action refers to creating frame
  after frame without planning until the end of the
  scene. Provides freshness and spontaneity.
• Pose-to-pose action refers to creating the
  keyframes first, then the in-betweens.
• Hierarchical modeling in computer animation is an
  evolution of pose-to-pose animation in classical
  animation. Planning ahead of the animation in a
  layered approach
• Start key framing at the top of the hierarchy
• Apply transformations level by level.

22
Principles of Animation

• Slow in and out
• Refers to the spacing of the in-between drawings
  between the extreme poses.
• Slowing in when approaching an extreme pose
  accentuates its effect.
• Slowing out when leaving an extreme pose
  accomplishes the same.
• Natural movement is reproduced by grouping
  in-betweens close to the extreme poses, with only
  one in-between in the middle.

23
Principles of Animation

• Arcs
• Refers to the arc shape of an action path between
  two extreme poses.
• Arcs used in nature, and their use in animation
  produces smoother movement.
• Path of action is controlled by the same spline
  that controls timing (slow-in and slow-out).
• Spline of action path should be independent from
  spline of timing.

24
Principles of Animation

• Exaggeration
• Refers to emphasizing ideas, by going to their
  heart and finding ways of conveying them clearly.
• Exaggeration can work with any components of a
  scene design, shapes, action, emotion, color,
  sound, but with balance.
• Some elements should remain natural as a
  reference for the audience.

25
Principles of Animation

• Secondary action
• Refers to an action that results directly from
  another action .
• Add a realistic complexity to an animation.
• Subordinate to the primary action.
• Change in secondary action should occur after
  change in primary action, otherwise it will not
  be seen.
• Example
• Facial expression is secondary to body movement
  if it is primary.

26
Principles of Animation

• Appeal
• Refers to anything the viewer likes to see
  charm, pleasant design, magnetism,
• Does not have to be cute or cuddly.
• Vary parts of the body, to look more natural and
  attractive.

27
Principles of Animation

• Personality
• The underlying goal of the principles enumerated
  above is to provide to the audience a character
  having a distinct personality, while looking
  familiar too.
• The character animations are subordinate to
  his/her thought processes.
• The animation is successful when the technique is
  forgotten by the audience, who is captivated by
  the action and emotions in the animation.
• First goal of the animator is to entertain, and
  requires
• a clear goal of what will entertain the audience.
• the tools and techniques to express the goal in a
  clear and attractive way.

28
Design of Animations

• Two types of systems
• Real-time animation - each frame in the sequence
  is viewed as it is generated. Rate of generation
  must be compatible with the refresh rate of the
  monitor (60/s, 30/s, ).
• Frame-by-frame animation each frame is first
  created and stored, then they are played on the
  monitor.
• Choice between the two depend on complexity of
  the animation, whether it needs to be in
  real-time or not,
• Real-time animations use a double buffering
  system
• Create a frame in one buffer, and during the time
  the screen is refreshed from that buffer,
• Construct the next frame in another buffer.

29
Design of Animations

• Development stages
• Storyboard layout outline of the action as a
  set of basic events occurring in the motion
  sequence, as a list or a series of sketeches
  associated with the actions.
• Object definitions basic shapes, characters,
  list of movements to be performed by each object.
• Key-frame specifications a detailed drawing of
  a key scene at an extreme timing in the action.
• In-between frames generation intermediate
  frames between the key-frames. Number depends
  upon the support 24 frames/s for film, 60
  frames/s or more for display monitors.

30
Design of Animations

• Example award-winning Luxo Jr. from Pixar
  Animation Studios (1986) is a movie designed
  using key-frame animation techniques.

31
Design of Animations

• Concepts of key-frame animation systems
• Generate a set of in-betweens between key frames.
• Motion paths can be spline curves or be based on
  natural movements.
• Shapes of objects can be transformed, for example
  through morphing transformation of an object
  between different shapes.