In scary films, a character somehow senses that something unidentifiable is very wrong as soon as he or she steps into a room. A surefire way to get a similarly unpleasant effect in a drawing is to be careless in handling perspective. The viewer will know something is wrong, even if it is not readily apparent. To make a convincing space, keep in mind the following three types of perspective systems, and implement the one most appropriate for your drawing.
Perspective is the visual effect that makes a square wall into a parallelogram and makes train tracks meet in the far distance—in your mind’s eye. The simplest way to ensure proper perspective is to adhere to a one-point perspective. This is easy: draw the horizon line in your composition, and then consider the line of sight—the exact direction that the viewer’s eye is meant to go. The intersection of these two lines is the vanishing point.
Once the vanishing point is established, the artist must simply ensure that all lines that recede into the distance on a parallel to the viewer’s line of sight—be it a row of trees, the roofline of a building, the molding along a ceiling, or rows of grapevines—intersect at the vanishing point. These lines are called convergence lines. (See Fig. 1 pictured right)
Two-point perspective is useful when a cube or rectangle is being viewed from an oblique angle—that is, if the viewer is looking at or into a corner. To correctly render the convergence lines in this situation, first establish the horizon line, then find the vanishing points at either side of the box’s corner. (See Fig. 2 pictured top half of below image) The box’s lines along the ground or floor, together with the lines along the roof or ceiling, will determine these vanishing points—assuming that the floor and the roof are parallel planes.
The third type is three-point perspective. This system allows you to draw from a worm’s-eye view or a bird’s-eye view. Three-point perspective is two-point perspective with the addition of a vanishing point either in the sky or in the ground. If you are looking up at a building at an oblique angle, the left and right outside edges of the building, normally parallel in one- and two-point perspective, converge toward a meeting point in the sky—assuming the building is shaped like a box or otherwise not designed by Frank Gehry.
A tall building scene from above will have convergence lines that meet underground. Obviously, the horizon line does not play a role in finding this third perspective point. (See Fig. 3 pictured bottom half of image left)
Similar geometry can help an artist accurately draw shadows—by drawing lines from the light source to the edges of the object casting the shadow, then continuing these lines onto the shadowed surface.