Perspective is a way of representing three-dimensional objects on a two-dimensional surface. The aim is to give the right impression of their height, width, depth, and position in relation to each other.
Of course you can deliberately distort perspective to make your work appear naïve or quirky. You can also use four or five point perspective if you want to start to bend time and space.
Perspective is only one way of creating the illusion of depth in your art.
The depth illusion
1. Linear perspective – By using either one point perspective, two point perspective, or three point perspective, an artist can create the illusion of space.
2. Overlapping – If part of an object is blocked from view it gives an idea of their relative position.
3. Size – Objects that are closer to a viewer appear larger than objects that are further off in the distance.
4. Placement on the surface– Generally, objects that are positioned lower on the picture plane will appear closer than objects that are positioned higher on the picture plane.
5. Colour and value – Distant objects tend to be lighter in value and cooler in colour (bluer). This is also known as aerial perspective. It’s all to do with the way our atmosphere absorbs light.
6. Detail – Distant objects have less detail and softer edges. Closer objects have sharper edges and more detail.
The eye level or horizon line – a horizontal line that runs across the paper or canvas to represent the viewer’s eye level and delineate where the sky meets the ground. It is there whether there are objects blocking your view or not. From a composition point of view it should rarely be in the centre of the composition, but ideally placed about one-third of the way up or down the piece.
Vanishing point – this is the point at which all receding parallel lines meet and it will be on the eye level line.
One point perspective
In one point perspective, surfaces that face the viewer appear as their true shape, without any distortion. Surfaces that travel away from the viewer, on the other hand, converge towards a single vanishing point. This is a point that is located directly in front of the viewer’s eyes, on the eye level line.
Drawing in one point perspective is usually appropriate when the subject is viewed ‘front-on’ (such as when looking directly at the face of a cube or the wall of building) or when looking directly down something long, like a road or railway.
Once the horizon line has been established, the vanishing points are placed. The vanishing point is defined as a point placed on the horizon line where objects begin to disappear because of distance. A good way to think of the vanishing point is by imagining yourself standing on a beach. Looking both directions, you can see endlessly down the beach. At some point, people on the beach walking away from you will become progressively smaller until they completely disappear at the horizon line.
Two point perspective
Two point perspective is useful when objects are not square on to the viewer. It uses two vanishing points, connected by a horizontal line.
In the illustration below you can see the eye level going through the head of the pedestrian just to prove the point! The vanishing points lie on the horizon whether you can see it or not.
Three point perspective
It should come as no surprise that three point perspective uses three vanishing points. The third vanishing point in three point perspective is not placed on the horizon line as seen with two point and one point perspective. Instead the third vanishing point is placed under or above the horizon line and may be off the picture plane.
The eye level and two vanishing points on it are marked, but the third is off the edge of the photo. Our brains often fail to see the third vanishing point and adjust the image, whereas cameras show the distortion distinctly. You may wish to exaggerate or change perspective or ignore it totally, as the artist.