perspective

Realistic representation of a three-dimensional object in two dimensions. One-point linear perspective is an effective way to give a picture depth and a sense of distance and space. It is based on three key principles: that the horizon line is always at eye-level; that the vanishing point is the point to which all lines parallel to the viewer recede; and that convergence lines meet at the vanishing point (all diagonal lines recede to the vanishing point). All horizontal and vertical lines remain parallel to one another to avoid objects becoming distorted. Two-point linear perspective follows the same principles, but uses two sets of converging lines and no horizontal lines; as a result there are two vanishing points.

In perspective the horizon line refers to the line where the sky and earth seem to meet; it is on this line that the vanishing point is located. Converging lines refer to the lines that appear to be parallel (as they actually are in reality), but if carried through on the picture plane would converge or meet at the vanishing point. These converging lines are the diagonal lines that give the work a sense of depth. Whatever falls above the horizon line will be seen from underneath by the viewer, while what falls below the horizon line will be seen from above by the viewer. If an object falls directly in front of the vanishing point, only the front will be visible - the viewer will be unable to see the sides, top, or underneath of the object. When using perspective all horizontal and vertical lines remain parallel to one another to avoid distortion of objects. The Last Supper (1495-98) by Leonardo da Vinci is an excellent example of one-point perspective.

The scientific principles of perspective were first laid down, using mathematics and close observation, during the Renaissance period. Many Renaissance artists were interested in tricking the eye into seeing three-dimensional forms in two-dimensional artworks. The rules of perspective were first applied to art by the 15th-century Italian painter Masaccio, who used slanted lines to make objects appear to extend back into space in his paintings; the technique was initially discovered by a contemporary, the architect Filippo Brunelleschi. Leonardo da Vinci and other Renaissance artists built on the use of perspective to evolve their own art. Attention to perspective would later see a revival in the work of the 19th-century Impressionist painter Alfred Sisley, most notably in his Le Chemin de la Machine à Louveciennes (1873) and La Neige à Louveciennes (1874).