Computer Animation

I

Introduction

Computer Animation, the simulation of on-screen movement produced by displaying successive images created with computer software and hardware.

II

Persistence of Vision

The perception of on-screen movement is caused by a phenomenon called “persistence of vision”: when presented with a series of rapidly changing images, the human brain cannot process them fast enough to see each image separately and instead perceives a single continuous moving image. In standard cinematic films there are 24 frames (images) per second—24 fps. The set speed of television systems varies in different countries and is either 25 fps or 30 fps. Animation created for playback on a computer, CD-ROM, or DVD requires 14 fps or more for fluid movement and depends on the available random access memory (RAM) and speed of the computer’s processor or CD-ROM/DVD drive. At a low speed of 8 fps or less, the moving image will appear jerky or the illusion of movement may be lost altogether.

III

The History of Computer Animation

A

Origins

One of the first applications of “interactive” computer graphics was the US government’s SAGE air defence system of the mid-1950s; missiles and aircraft were detected by radar with their positions displayed on screen. Operators then selected targets by pointing at them with a light pen. The resulting tracking/interception calculations were relayed to command stations elsewhere.

B

Early Computer Games

By the end of the 1960s, computer graphics had influenced some areas of the scientific community, but had not reached the general public. There were no commercially available video games; nor was there any CGI (computer-generated imagery) on television, or awareness of computer animation. The first interactive arcade game, Pong (simulated ping-pong), was introduced in the United States by Atari in November 1972. However, it was only in 1974 that Atari managed to bring down the retail price to a reasonable level and attract the home market worldwide. This was achieved by integrating features such as on-screen scoring and sound into a single computer chip (a microprocessor built from wafer-thin layers of silicon, chemicals, gases, and metals etched with a three-dimensional circuit that conducted electricity to execute a set of programmed instructions). The on-screen graphics consisted of a dotted vertical line representing the ping-pong net and simple geometric shapes representing bats and balls. Another early game, developed by Taito and published in the West by Midway, was Space Invaders, which became so popular that the word for video game machine in Japan and France became “space invader”.