Computer-Generated Imagery (also known as CGI) is the application of the field of computer graphics or, more specifically, 3D computer graphics to special effects in films, television programs, commercials, simulators and simulation generally, and printed media.
ReBoot is the first completely Computer Generated production.
In the episode Racing the Clock, Bob uses an x-ray to scan a package. The mask inside the package can be seen in wireframe. At a certain angle, Bob and Dot can be seen through the x-ray. The interior of their bodies was shown to be wire-frame. This is the construct that CGI uses to create any Computer Generated Image.