Orthographic Projections

Abstract

We may now address the problem of drawing views of three-dimensional objects on our (necessarily) two-dimensional graphics screen. The simple method we describe here is a direct generalisation of the method introduced in chapter 4 for two-dimensional objects. Again it involves the use of (up to) three positions. To illustrate these ideas we first give a brief outline, and then expand on this by using pictorial and numerical examples. We start by defining an arbitrary but fixed triad of axes in space which we call the ABSOLUTE system. Then, as in the two-dimensional case, we consider the three positions: (1) the SETUP position, (2) the ACTUAL position and (3) the OBSERVED position.