Using Ellipses to Define Surface Contours

In this illustration the ellipses have been arranged to create the illusion of a flat plane. As these shapes recede toward the background, their minor axes diminish in size at a constant rate. Compare this rate of change with that in the illustration at right.

Here a curved surface is indicated. In the foreground, where part of the surface is nearly parallel to the picture plane, the changes in minor axes are gradual. As the surface curves away from the picture plane, the ellipses' minor axes diminish rapidly.

Ellipses have been arranged to create the illusion of a horizontal plane that recedes in space, then curves upward into a vertical plane. This is accomplished by making the minor axes progressively smaller, then larger.

The ellipse pattern creates the illusion of a large, horizontal cylinder.

The texture of this tree trunk is an example of how ellipses describe a curved contour.

Just as the ellipses here indicate a flat plane, so too do the bases of the tree trunks, which are circular and therefore fit into imaginary ellipses appropriate for circles seen at that angle and distance.

Here the ellipses and the bases of the trees are arranged to create tne impression that they rest on a curving (cylindrical) surface.