5.1. Introduction
All forms of engineering and technical work require that a two-
dimensional surface (paper) be used to communicate ideas
and the physical description of a variety of shapes. Here
projections have been divided in to two basic categories;
pictorial and multi view. This simple division separates single
view projections (oblique, perspective and isometric) from
multi view projections (orthographic). Theoretically,
projections can be classified as convergent and parallel, or
divided in to three systems of projection: perspective, oblique,
and orthographic. Division of types based on whether the
drawing is a one view or multi view projection sufficiently
separate projection types in to those used for engineering
working drawings (orthographic) and those used for display
(architectural rendering, technical illustrations etc)
In short, one of the best ways to communicate one's ideas is
through some form of picture or drawing. This is especially
true for the engineer. The purpose of this chapter is to give
you the basics of engineering sketching and drawing.
We will treat "sketching" and "drawing" as one. "Sketching"
generally, means freehand drawing. "Drawing" usually, means
using drawing instruments, from compasses to computers to
bring precision to the drawings.