Perspective for animators

In drawn animation one of the most difficult things to create is a sense of depth, with characters which are not flat shapes on a flat background but have the appearance of being solid in a three dimensional world. That means drawing and animating in perspective, writes George Collin.

There are many books available on perspective drawing and it is not my intention to simply duplicate the kind of information they give. My aim is to encourage a greater interest in perspective as it applies to animation. Two particular aspects of perspective have a special application in animation: creating movement in perspective and the neglected art of cylindrical perspective. But before considering these it is necessary to deal with the basic rules of perspective which apply to drawing a single still image.

Imagine a sheet of glass between the artist and his subject. The scene which he sees before him can be replaced by an image drawn on the glass. In this sense all perspective drawing is an illusion, it seeks to mimic the actual scene.

This system of painting on glass is a standard technique in special effects cinematography. The “ideal” perspective drawing is obviously like a photograph. But the history of perspective goes back long before films or photography.

The basic idea of perspective was known and used by the Greeks and Romans. It seems to have fallen into disuse after the Roman Empire declined but was reintroduced by Renaissance artists and has been a feature of European art ever since.

Before we get too deeply involved in the technique of perspective it is worth considering why perspective was not used by other cultures and in other ages. The answer lies in the purpose of art. Art of whatever culture seeks to represent the world around us and the imagination within us. Even in our own culture this representation is often highly stylised. Look at a picture book for young children; the objects, say a cup or a ball, are usually nothing like a photograph. The colours are gaudy, there is no light and shade, they have thick outlines. But in a sense they correspond with how we see. Just because our eye contains a lens does not mean that we see the world like a camera. The eye merely collects information which the brain composes into a meaningful image.

An image does not need perfect perspective to fulfil its function and many cultures have deliberately chosen to ignore complex perspective. Perspective is not a superior form of art, it is merely a particular branch. In the same way it is possible to animate without applying any of the rules of perspective, in fact you can openly flout them. But I will assume that you want to give to your animation some illusion of real depth.

The form of perspective we are considering here (sometimes known as Plano-linear perspective) has strict limits. Firstly it assumes that we look at the scene with one eye only, secondly it assumes that we stare at a fixed point in the scene, although our eye takes in a field of view all around this point (more about angles of view later). Thirdly it assumes that the sheet of glass upon which we draw (or imagine the picture to be drawn) is so placed that our line of sight is square on, i.e. forms a right angle with the surface of the glass. But the line of sight does not have to be in the centre of the picture. It often looks best if placed to one side and slightly above or below the middle.

It follows that the glass will only be vertical if the line of sight is horizontal, i.e. parallel with the ground. If the artist is looking upwards or downwards, then the glass must be tilted accordingly.

It is all too easy to learn a rule of perspective and then produce an impossible looking picture, because these rules have limitations. They are merely rules of convenience. Never lose sight of the basic rule, i.e. the principle of the sheet of glass.

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