Solid modelling

Abstract

It was probably the realisation that the 3D wire-frame representation of things, superior as it was to paper and pencil, was still limited in its ability to represent objects that provided the motivation to produce solid modellers. There was an obvious problem in visualising the object. You cannot tell which line is behind and which in front, and even when you know it is sometimes difficult to make one’s mind see it that way round, particularly when viewing something from below. Besides the visualisation problem there is nothing in a wire-frame model to say unambiguously which part of space is inside the object and which outside, and it is possible to draw objects which can never physically exist such as the well-known one shown in Figure 15.1.