Engineering Graphic Modelling

3.3

THE DRAWING CODE

TYPES OF PROJECTION

In order to represent a three dimensional solid object on a two

dimensional medium, such as a sheet of paper, it is necessary to

adopt a projection convention, i.e. a given point on the object is

represented by a given point on the paper, this transfer being according

to set rules. The following projections are

used:

—

3.1 Orthographic

3.2 Isometric

3.3 Dimetric

3.4 Trimetric

3.5 Oblique

3.6 Single-point perspective

3.7 Two-point perspective

3.8 Three-point perspective

'Pictorial'

projections

θ

e

THIRD ANGLE

FIRST ANGLE

PERSPECTIVE

In addition non-conventional representations may be used

particularl