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Isometric drawings and oblique projections are both often used by engineers as part of their technical drawings and illustrations.

Oblique projections

Oblique projections are created using oblique grid paper and use 45-degree lines to create a 3D graphical image. Oblique drawings are not very realistic as it is impossible to see the front of an object straight on and the side at the same time. They can be useful to sketch at speed or to show the front and side of a building.

Isometric drawings

Isometric drawings are commonly used in technical drawing to show an item in 3D on a 2D page. Isometric drawings, sometimes called isometric projections, are a good way of showing measurements and how components fit together. Unlike perspective drawings, they don’t get smaller as the lines go into the distance.

There are three main rules to isometric drawing:

• horizontal edges are drawn at 30 degrees
• vertical edges are drawn as vertical lines
• parallel edges appear as parallel lines

Isometric paper can be used to draw 3D shapes - for example the cube below is drawn using the dots as a guide. The vertical lines always remain vertical, but the horizontal lines are at angles.

Isometric drawings can be used to show the scale of a product as well as a 3D representation.

Example

Below are two cubes drawn in isometric:

= 30 ÷ 60

= 0.5

This means the second cube has been drawn to half scale, also written as 1:2.