Analytic geometry of the sort usually found in multivariable calculus enters our discussion as we imagine displaying a three dimensional object on a two-dimensional computer screen or photographic print. Figure 2 depicts the two most common ways of accomplishing such a projection.

(a) *Perspective projection* (b) *Orthographic projection*

**Figure 2**

(a) *Perspective projection* (b) *Orthographic projection*

**Figure 3**

As one can see from Figure 3, a cube drawn with a perspective projection has back edges that are smaller in size than the front edges, suggestive of the greater distance from the eye. In contrast, the orthographic projection yields front and back edges of the same size. Both projection methods are fundamental in computer graphics, and I think a discussion of them can provide a compelling application of certain topics from calculus and linear algebra.

Tom Farmer, "Geometric Photo Manipulation - Projections," *Convergence* (October 2005)