ABSTRACT
Figure 18.1 shows a polygon. It is the outline of a shape, drawn with straight line segments. Since such shapes are all a printer or plotter can draw, just about every computer-generated drawing consists of polygons. If we add an “eye” to the bird-shaped polygon from
Figure 18.1, and if we apply a sequence of rotations and translations to it, then we arrive at Figure 18.2. It turns out copies of our special bird polygon can cover the whole plane! This technique is also present in the Escher illustration in Figure 6.8.
