We live in a three-dimensional world of depth. When we look around us,
some things seem closer, some further away. The artist can also show the
illusion of depth by using the following means:
Size
& Vertical Location
Since
objects in our environment look smaller when they are farther away, the
easiest way to show depth is to vary the size of objects, with closer
objects being larger and more distant objects being smaller. As well,
we perceive objects that are higher on the page and smaller as being further
away than objects which are in the forefront of a picture.
Overlapping
When objects are partially obscured by other objects in front of them,
we perceive them as further back than the covering objects. We do not
see them as incomplete forms, just further back.
Detail (Aerial or Atmospheric Perspective)
Atmospheric perspective uses color and value contrasts to show depth. Objects which are further away generally have less distinct contrast - they may fade into the background or become indistinct dark areas. The foreground objects will be clear with sharper contrast. Here is a link to Leonardo da Vinci's use of aerial perspective
Linear Perspective
(Converging Lines)
Linear perspective
is based on the idea that all lines will converge on a common point on
the horizon called the vanishing point. You have observed linear perspective
when you notice that the lines on the highway appear to meet at a point
in the distance. Artists use linear perspective to create a focal point
for a picture. Any walls, ceilings, floors or other objects with lines
will appear to come together at the horizon line. These lines converging
lead our eyes towards that point. Often, the most important object or
person in the picture will be located at that point. You can see in the
drawing above how all the lines in the drawing seem to lead your eye toward
the church in the center back of the drawing.
Other types of perspective, such as two-point or multipoint perspective
are also used. Two-point perspective, which occurs when you display a
building from a corner view, as opposed to a front view, is often used
by architects to show a more three-dimensional view of a building. To
learn the mechanics of setting up a picture using linear or multipoint
perspective check out this site: Art Studio Chalkboard
Here is a web page which investigates linear perspective in Leonardo da
Vinci's work: