To animate literally means “to give life to”. Animating is moving something (or making something appear to move) that cannot move itself, whether it is a puppet of King Kong, a hand-drawn image of Snow White, the hands of a watch, or a synthetic image of a wooden toy cowboy. Animation has been used to teach and entertain from the early days of puppetry and continues to be used today in film and video. It is a powerful tool to spark the imagination of the child in all of us. Animation adds the dimension of time to computer graphics. This opens up great potential for transmitting information and knowledge to the viewer while igniting the emotions. Animation also creates a whole new set of problems for those who produce the images that constitute the animated sequence. To animate something, the animator has to be able to control, either directly or indirectly, how the thing is to move through time and space as well as how it might change its own shape or appearance over time.
In computer animation, any value that can be changed can be animated. An object’s position and orientation are obvious candidates for animation, but all of the following can be animated as well: the object’s shape, its shading parameters, its texture coordinates, the light source parameters, and the camera parameters. To set the context for computer animation, it is important to understand its heritage, its history, and certain relevant concepts like motion perception, the technical evolution of animation, animation production, and notable works in computer animation.
The fundamental objective of computer animation programming is to select techniques and design tools that are expressive enough for animators to specify what they intend, yet at the same time are powerful enough to relieve animators from specifying any details they are not interested in. Obviously, no one tool is going to be right for every animator, for every animation, or even for every scene in a single animation. The appropriateness of a particular animation tool depends on the effect desired and the control required by the animator. An artistic piece of animation will usually require tools different from those required by an animation that simulates reality or educates a patient.