Animation

1. Animation Vladimir Savchenko vsavchen@k.hosei.ac.jp

2. Preface • What is animation? • Animation is the rapid display of a sequence of images of 2-D artwork or model positions in order to create an illusion of movement. It is an optical illusion of motion due to the phenomenon of persistence of vision. • An optical illusion - the information gathered by the eye is processed by the brain to give, on the face of it, a percept that does not tally with a physical measurement of the stimulus source. • Motion means a continuous change in the position of a body relative to a reference point, as measured by a particular observer in a particular frame of reference.

3. Preface • What is animation? • According to the theory of persistence of vision, the perceptual processes of the retina of the human eye retains an image for a brief moment. Persistence of vision is said to account for the illusion of motion which results when a series of film images are displayed in quick succession, rather than the perception of the individual frames in the series. • Observation is the observing of phenomena, actions, or events • In physics, observation refers to a provided set of axes from which an observer can measure the position and motion of all points in a system, as well as the orientation of objects in it.

4. Preface • Animation techniques • Traditional animation - Also called cel animation, the frames of a traditionally animated movie are hand-drawn. • Walt Disney developed a number of principles • Computer graphics animators have adapted them to 3D

5. Preface • Animation techniques • Computer animation • Computer animation encompasses a variety of techniques, the unifying idea being that the animation is created digitally on a computer.

6. Preface 2D animation • Figures are created and/or edited on the computer using 2D bitmap graphics or created and edited using 2D vector graphics. This includes automated computerized versions of traditional animation techniques such as of tweening, morphing, onion skinning and interpolated rotoscoping. • Tweening, short for in-betweening, is the process of generating intermediate frames between two images to give the appearance that the first image evolves smoothly into the second image.

7. Preface 2D animation • Morphing is a special effect in animations that changes (or morphs) one image into another through a seamless transition. • Onion skinning is a 2D computer graphics term for a technique used in creating animated cartoons and editing movies to see several frames at once. • Interpolation is a method of constructing new data points from a discrete set of known data points.

8. Preface 3D animation • Figures are created in the computer using ,for example, polygons. To allow these meshes to move they are given a digital armature (sculpture). This process is called rigging. Various other techniques can be applied, such as mathematical functions (gravity), simulated fur or hair, effects such as fire and water and the use of motion capture to name but a few. • The armature is analogous to the major skeleton and has essentially the same purpose: to hold the body erect.

9. Preface • Animation principles 1. Squash and stretch 2. Staging 3. Timing 4. Anticipation 5. Follow through 6. Overlapping action 7. Secondary action 8. Straight-ahead vs. pose-to-pose vs. blocking 9. Slow in, slow out 10. Exaggeration 11. Appeal

10. Preface • Animation principles • Squash and stretch Squash: flatten an object or character by pressure or by its own power Stretch: used to increase the sense of speed and emphasize the squash by contrast • Note: keep volume constant

11. Preface • Animation principles Staging • Present the idea so it is unmistakably clear • Audience can only see one thing at a time • Useful guide: stage actions in silhouette • In dialogue, character faces ¾ towards the camera, not right at each other

12. Preface • Animation principles Timing • Timing affects weight: – Light object move quickly – Heavier objects move more slowly • Timing can completely change the meaning of an action

13. Preface • Animation principles Anticipation • An action breaks down into: – Anticipation – Action – Reaction • Anatomical motivation: a muscle must extend before it can contract • Prepares audience for action so they know what to expect • Directs audience’s attention • Amount of anticipation can affect perception of speed and weight

14. Preface • Animation principle Secondary action • An action that emphasizes the main point, but is secondary to it.

15. Preface • Animation principles Straight-ahead vs. pose-to-pose vs. blocking • Straight ahead: proceed from frame to frame without planning where you want to be in ten frames. Can be wild, spontaneous. • Pose-to-pose: Define keyframes and “inbetweens”. • Blocking: computer graphics animators adaptation: – Start key – framing at the top of the hierarchy – Refine level by level – Keyframes for different parts need not happen at the same time.

16. Preface • Animation principles Slow in, slow out • An extreme pose can be emphasized by slowing down as you get to it (and as you leave it)

17. Preface • Animation principles Exaggeration - Get to the heart of the idea and emphasize it so the audience can see it.

18. Preface • Animation principles Appeal • The character must interest the viewer. • It doesn’t have to be cute and cuddly. • Design, simplicity, behavior all affect appeal. • Note: avoid perfect symmetries • Example: Luxo, Jr. is made to appear childlike

19. Examples. Animation by space mapping technique • The space mapping technique is applied in 3D space and can serve for computing of surface transformations according to the user demands • The left image shows the “Lion-dog” model (courtesy of Yutaka Ohtake and A Belyev of Max-Planck-Institut für Informatik) (24930 vertices, 50000 polygons), whose surface was generated from range data • The right image shows plausible deformations after applying space deformations by two 3D points (the time required to calculate deformations is about 0.0001 seconds)

20. Examples. Facial Animation emotions1[1].avi (7000 triangles, 100 frames per sec) elasticbox1[1].avi

21. Volume visualization and animation • Temporal transformation or metamorphosis can be useful in different applications, for instance, artistic animation or recognition tasks. arhnew.avi • Figures illustrate shapes constructed by the linear interpolation of two (volume) shapes with using a linear blending function which specify the relative contribution of each shape on the resulting blended shape.

22. Character animation • NekoAnimation\Neko.html

23. Character animation • fontanim.mov

24. Key-frame animation • Artificial fish • fish4.avi

25. Particle physically based animation • NekoAnimation\Cometaimage2.html