Visual Perspective Perspective in art is the way that artists represent three-dimensional objects on the two dimensions of their

Visual Perspective
Good morning, everyone. Today, I want to start with a look at visual perspective. First, we’ll look briefly at the kinds of perspective, and then we’ll look very quickly at its history in art. Just in case you don’t know what we’re discussing— perspective in art is the way that artists represent three-dimensional objects on the two dimensions of their canvas.
There are two basic sorts of visual perspective—aerial perspective and linear perspective.[1]Aerial perspective—and "aerial" just means "air" or "atmospheric", not your view from an airplane![2]—aerial perspective is the way that the atmosphere affects how we see things, especially distant things.[3]I won’t try to go into the laws of physics that are involved here, but it is aerial perspective that makes a mountain in the distance appear to be a different color, that makes it seem hazier—less distinct—than closer objects. These are effects that realistic artists attempt to reproduce carefully.[4]And impressionists also use it to create their own special effects. Just think of many of Turner’s landscapes—or cityscapes like his "Dido Building Carthage"—to get an idea of how the air can affect what we see.
[4]The other perspective, linear perspective, is the way that things seem to get smaller the farther away they get.[6]A classic example of this is the way we perceive railroad tracks or a line of telephone poles running away from us.[7]They seem to get smaller and smaller as they recede—until they vanish in a point on the horizon—and this point is appropriately called "the vanishing point". This effect happens whenever there are parallel lines, like the two train tracks, or the tops and bottoms of the telephone poles.
Now, an object or a scene may have more than one vanishing point. A cube with one of its faces squarely perpendicular to us has a single vanishing point, directly behind it and on the horizon.[8]But a cube with one of its vertical edges facing us has two vanishing points instead—one for the right-hand face and one for the left-hand face, and these points are off to the right and left respectively, on the horizon, where the parallel lines of the faces seem to converge.[9]And then if this same cube is viewed from somewhat above or below, it will have three vanishing points—one to the right, one to the left, and a third one behind it and below or above the horizon. This is easy to visualize if you look up at a corner building from its street intersection. You can look down one street to see the right-hand vanishing point, look down the cross-street to see the left-hand vanishing point, and then look up along the corner of the building to visualize the third vanishing point.
These kinds of perspective are easy to see if we view geometrical shapes or manmade structures, but of course natural scenes don’t have any sets of parallel lines, so they have no vanishing points—but that doesn’t mean that they don’t exhibit perspective. OK So much for the two perspectives, now a bit of history about the perspectives. The laws of optics were not understood at all in early Western art. Artists recognized the effect, of course, but they were unable to figure out how to represent it accurately.[10]/[11]From the paintings inside the Egyptian pyramids to the illustrations in medieval Christian churches, nearer people were simply drawn larger, or drawn lower in the picture, or drawn so as to cover the people farther away. There was no real understanding of how the physics of perception worked—they never got a grasp on the idea of the vanishing point.
In the 13th and 14th centuries, before linear perspective was discovered, artists occasionally employed something called reverse perspective, in which parallel lines splay rather than converge as they approach the horizon line. One of the rules set forth in an early artists’ manual is that elements above the eye of the viewer tend downward, while elements below the viewer’s eye tend upward. While arbitrary tilting of lines upward and downward can create unusual effects, this is generally considered to be a significant step in the progression toward the rational application of linear perspective.
[12]And then came the Renaissance, the rebirth of learning and the sciences. This was a hotbed of scientific thought—Da Vinci, Galileo, Newton and Filippo Brunelleschi.[13]Brunelleschi was a fifteenth century Florentine architect who conducted several optical experiments and discovered the rules of perspective. With what he’d learned,[14]he drew a very accurate picture of San Giovanni Bapistery in Florence, and then he made a small peep hole in the middle of it. He carried it into the street and amazed all his acquaintances by having them look through the peep hole from the back of his picture—first, at a mirror which reflected the image into the viewer’s line of sight. Then, Brunelleschi would quickly withdraw the mirror—leaving the viewer peeping at the real Bapistery, whose perspective had been replicated perfectly!
Other Italian artists, notably Donatello, began using Brunelleschi’s methods for accurate linear perspective and his ideas soon spread throughout Europe.[15]The development of effective aerial perspective, on the other hand, was developed by the Flemish and Dutch masters of this same period, and can be seen at its best in works like Jan van Eyck’s "The Virgin of Chancellor Rolin". But that’s another story.
OK I have outlined the two perspectives for you and I also talked about the history of the development of perspectives. Next time, we shall go to the workshop of drafting some drawings with the help of perspectives.