Multimedia animation

Animation is the changing of an image over time.
Animation is usually created rather than filmed from a real life sequence, though sometimes animation may be combined with video footage.

Most often animation will allow different timings between frames, or even object moving on top of a background, whereas video is recorded from real life sequences and sets a constant timing (on a TV this is 30 frames per second, most PC videos are set to 15 fps.). Animation may be copied to a video format to enable distribution on standard videotape or film.

VRML (Virtual Reality Modelling language) is an emerging form of animation where objects are defined as wire frames then rendered (filled in) in real time. This is being extended into creating "worlds" that you can then move about in, for example in Internet connected virtual shopping malls.

Microsoft has also developed 3D animation technology, where you can move in a 3D space and this automatically changes your surroundings. It also enables you to interact with your background. This technology has been used in the CD "The Neverhood".

Object

Object - movement of unchanged text and objects around the screen. Used extensively in presentation packages to introduce text and graphics on the screen.

Marquee - displays "Object" animation

Typing tutor (requires VBScript capable browser) shows shark/fish moving over a background.

Object with tweening

Here the object changes over time. The object moves over a stage background. Extensively used in "living books" where the animals move over a background.

Tweening is a traditional animation term that describes the process in which a lead animator draws only the animation frames where major changes take place, called keyframes. Assistants draw the frames in between.

In products such as Director, you define properties for a sprite in frames called keyframes and let Director change the properties in the frames in between. Properties that can be tweened are position, size, rotation, skew, blend, and foreground and background color.

Frame (Cel)

Frame-by-frame animation involves manually creating every frame in an animation. The different frames or screens are rapidly displayed to simulate motion.

FLI	Flick files - where successive bitmaps are stored in one file, then played.
GIF	The GIF file format allows for animated gifs. It allows you to change the display rate between frames (unlike video formats)

The final animation may be stored in a movie format such as;

MOV	Apple Quicktime movie format.
AVI	(Audio video interleave) Standard Windows movie format
MPG	Industry standard video format.

[12 frame Animated gif]

To produce the animation shown left requires a sequence of single frames to be drawn (below) as individual files (gifs), then combined using software such as Microsofts Gif animator.

[Frames that make up animated gif]

Vector

Each graphic element is stored as a mathematical expression that describes its size, shape, position and other characteristics. These expressions take up far less space than the equivalent bitmapped images. They are especially suited to logo treatments and other effects that can be easily rendered as lines and curves.

At present (May 97) for Internet use there are four competing formats.

Flash (Macromedia), Quick Time 3.0 (Apple), Vectorium (Paceworks) and Electrifier (Lari Software)

At present each requires it's own plug in to a browser.

Beale S (1997, May 26)

Virtual Reality

A "world" is constructed of polygons in a 3D plane. The computer then renders in real time the world allowing you to walk through the world.

VRML examples

Techniques

Morphing

g_hjm11.gif (27757 bytes)

(Morphing) - changing one image into another - common in many modern science fiction movies.

This is achieved by providing a morph program with a source and target picture then mapping points on the source picture to the target picture.

The file is then saved usually in a Video format (AVI, MOV) or (FLI).

Ray tracing

bugslife.gif (60828 bytes)

Uses quite a different technique to produce bitmaps.

Using mathematical models in 3-Dimensions a "Virutal image" is created. This image is then "Rendered" (filled in) to give lighting effects. Use extensively in animation.