# Isometric and perspective

and are commonly used in technical drawing to show an item in 3D on a 2D page.

## Perspective

Perspective drawings show an object in 3D getting smaller in the distance.

- This shows an object from the front in a realistic way as it gets smaller going into the distance. The front view goes back towards a , which is a point on the horizon line that all lines meet at.

Single-point perspective

- This shows an object from the side with two vanishing points. It gives the most realistic view of a product as it shows the item edge on, as we would see it. It is often used to produce realistic drawings of an object.

Two-point perspective

Single-point perspective is often used by to show a view into a room, whereas two-point perspective is often used by to show realistic building ideas.

## Isometric

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:

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

Isometric drawings are used to show a graphical representation of a 3D object. They are used by architects and engineers to communicate their ideas to the client and manufacturer, showing the product or design .

### Example

Below are two cubes drawn in isometric:

Scale factor = smaller length ÷ larger length

= 30 ÷ 60

= 0.5

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

Question

Work out the scale factor of the smaller cuboid below:

Scale factor = 30 ÷ 40 or 60 ÷ 80

= 0.75

Also represented as a factor 34 or a ratio 3:4.