2D ANIMATION

Project Requirements

• Creation of basic bouncing ball

• Creation of an individual animation– Storyboard– Drawings/Digital frames– Export

3

Moving pictures

• Animation—making objects that appear to move on the screen—is done by displaying a series of still pictures, one after the other, in rapid succession– Generally you should try for at least 20

pictures/second

Principles of AnimationAnimation is possible because of a a biological phenomenon known as

persistence of vision

An object seen by the human eye remains chemically mapped on the eye’s retina for a brief time after viewing.

Combined with the human mind’s need to conceptually complete a perceived action.

This makes it possible for a series of images that are changed very slightly and very rapidly, one after the other, seem like continuous motion .

Animation and Frame Rates

TV video builds 30 entire frames or pictures every second.

Movies are shot at a shutter rate of 24 frames per second, but using projections tricks the flicker is increased to 48.

On some projectors each frame is shown 3 times before the next frame, for a total of 72 flickers per second which helps eliminate the flicker effect.

Cel Animation – plays at 24 frames per second.

Cel Animation

Made famous by Disney24 frames per second therefore a minute may require as

many as 1,440 separate frames.

Cel animation: is based on changes that occur from one frame to the next.

Cel stands for celluloid which is a clear sheet with images drawn on them.

The celluloid images are place on a background that is usually stationary.

The background remain fixed as the images changes.

Path Animation

Moves an object along a predetermined path on the screenThe path can be a straight line or have a number of curves.

Starts with keyframes (the first and last frame of an action).

The series of frames in between the keyframes are drawn in a process called tweening.

Tweening requires calculating the number of frames between keyframes and the path the action takes, and then actually takes, and then sketches a series of progressively different outlines.

Computer Animation

Typically employs the same logic and procedural concepts as cel animation

You can usually set your own frame rate

At 15 frames a second the animation may appear jerky and slow

2-D animation can be an acceptable alternative to the expense of creating video

Animation File Formats

Software File FormatDirector .dir & .dcrAnimator Pro .fliStudio Max .maxSuperCard and Director .picsWindows Audio Video Interleaved .aviMacintosh .qt & .movMotion Video .mpegCompuServe .gifFlash .swfShockwave .dcr

Conventional Animation

• Draw each frame of the animation– great control– tedious

• Reduce burden with cel animation– layer– keyframe– inbetween– cel panoramas

Computer-Assisted Animation

• Keyframing – automate the inbetweening– good control– less tedious– creating a good animationstill requires considerable skilland talent

Computer-Assisted Animation

• Physically Based Animation– Assign physical properties to objects (masses, forces, inertial) – Simulate physics by solving equations– Realistic but difficult to control

• Motion Capture– Captures style, subtle nuances and realism– You must observe someone do something

Keyframing

• Describe motion of objects as a function of time from a set of key object positions. In short, compute the inbetween frames.

Interpolating Key Frames

Interpolation is not fool proof. The splines may undershoot and cause interpenetration. The animator must also keep an eye out for these types of side-effects.

Traditional Animation Principles

• The in-betweening, was once a job for apprentice animators. We described the automatic interpolation techniques that accomplish these tasks automatically. However, the animator still has to draw the key frames. This is an art form and precisely why the experienced animators were spared the in-betweening work even before automatic techniques.

• The classical paper on animation by John Lasseter from Pixar surveys some the standard animation techniques:

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

Squash and Stretch Cont.

• Can relieve the disturbing effect of strobing.

Timing• Timing affects weight:

– Light object move quickly– Heavier objects move slower

• Timing completely changes the interpretation of the motion. Because the timing is critical, the animators used the draw a time scale next to the keyframe to indicate how to generate the in-between frames.

Anticipation

• An action breaks to:– 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.