Computer Animation

I

Introduction

Computer Animation, creation of the illusion of motion by viewing a succession of computer-generated still images. Prior to the advent of computers, animation was accomplished by filming hand-drawn or painted sequences on plastic or paper, called cels, one frame at a time. Computers were first used to control the movements of the artwork and the camera. Now computers create the artwork and simulate the camera.

Computer animation can be used to create special effects and to simulate images that would be impossible to show with nonanimation techniques, such as a spacecraft flying by the planet Saturn. Computer animation can also produce images from scientific data, and it has been used to visualize large quantities of data in the study of interactions in complex systems, such as fluid dynamics, particle collisions, and the development of severe storms. These mathematically based models use animation to help researchers see relationships that might otherwise be overlooked. Computer animation has also been used in legal cases to reconstruct accidents.

II

How Computer Animation Works

In traditional frame-by-frame animation, the illusion of motion is created by filming a sequence of hand-painted cels and then playing the images back at high speeds, typically 14 to 30 frames per second. In computer animation, the art is created using computer programs, frame by frame, and then recorded, edited, and played back.

Another computer animation technique is real-time animation, in which the frames are created using a computer and then immediately displayed on a computer monitor. This technique eliminates the interim step of digitally recording the images; however, real-time animation currently does not produce high quality or richly detailed results. It is best suited for creating simple animations for video games.

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III

Computer-Assisted Animation

In the traditional process of animation, a storyboard (a scene-by-scene illustration of the plot) is drawn first, the soundtrack is completed, and a senior animator creates key animation frames. Other animators then draw the frames in between the key scenes, color is added, and each frame is then filmed. Computers can be used to assist or replace every phase of this animation process.

A

In-Betweening

The process of creating the intermediate frames to fill in the action from key scene to key scene is called in-betweening. Techniques have been developed that allow the computer to create the in-between frames by estimating common points from key frame to key frame. In the simplest case, the computer draws the in-between movement of two corresponding points by calculating the mid-point distance. Repeated calculation of mid-points can provide the illusion of smooth and continuous motion.

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