There are several different ways to create the illusion of depth and space in a painting, whether the painting is representational or abstract. If you are a representational painter, it is important to be able to translate what you see in three dimensions onto a two-dimensional surface and to convincingly evoke the sense of depth and space. If you are an abstract painter, learning how to create different spatial effects can make your paintings stronger and more interesting. Here are some ways to achieve that.
When some objects in a composition are partially hidden by others, it gives the effect of overlapping objects and creates the illusion of space and three-dimensionality. For example, in Giorgio Morandi's deceivingly simple still-life paintings, shallow space and depth are conveyed by the overlapping bottles, allowing the viewer to perceive distinct rows. In landscape painting, layering the planes of the foreground, middle ground, and background lend to the illusion of space.
Linear perspective occurs when parallel lines, such as the side rails of train tracks, seem to converge to a single vanishing point in the distance. It is a technique that Renaissance artists discovered and used to show deep space. This effect occurs with one, two, and three-point perspective.
In a painting, objects appear closer or further away depending on size. Those that are larger seem to be closer; those that are smaller seem to be farther away. For example, in foreshortening, which is a type of perspective, an apple held in an outstretched hand that is coming toward the viewer will appear very large relative to the head of the person holding the apple, even though we know that in real life, the apple is smaller than the head.
Atmospheric perspective shows the effect of layers of atmosphere between the viewer and the distant subject. As things, such as mountains, become further away, they tend to become lighter in value (tone), less detailed, and bluer in hue as they take on the color of the atmosphere. You can also see this effect on a foggy day. Those things that are closer to you are clearer, brighter, and sharper; those things farther away are lighter in value and less distinct.
Colors have three main characteristics: hue, saturation, and value. Hue refers to the color itself. In general, given the same saturation and value, colors that are warmer in hue (contain more yellow) tend to come forward in a painting, and those that are cooler (contain more blue), tend to recede. Also, colors that are more saturated (intense) come forward, while those that are less saturated (more neutral), tend to sit back in a painting. Value is how light or dark a color is and is very important in creating the effect of representational space.
Things with more detail and visible texture seem to appear closer. Things with less detail appear farther away. This is true in terms of paint application, too. Thick, textural paint seems closer to the viewer than paint that is applied thinly or smoothly.
These are general guidelines that will help you create depth and space in your paintings. Now that you are aware of them, try playing with and manipulating the paint to see how to best achieve your desired results.