Minor and Major Axes
As artists we are interested in two measurements on an ellipse: the minor axis, which is the shortest line that can be drawn through the center of the ellipse, and the major axis, which is the longest line that can be drawn through the center. The major and minor axes are perpendicular to each other.
We look to the minor axis to determine the relation of an object's surface to our eye level, the front-to-back tilt of a plane, and how close a plane is to us. For example, if we tip a glass to drink from it, the minor axis of the ellipse-the rim of the glass- gets longer and depicts the forward tilt of the glass. So, to draw a plane so it appears to tilt forward in space, increase the length of its minor axis.
To understand how elliptical perspective works in 'the perception and depiction of distance, imagine several glasses on a table, some close to your view and others far away. The ellipse formed by the rim of a glass close by will be rounder (in other words, will have a longer minor axis) than that of a glass on the far side of the table (which will have a shorter minor axis). Regardless of the glasses' size, if their rims are at the same height, those that appear as narrow ellipses belong to the glasses farthest away from you.
The horizon is also called the eye level. In the same way that the opening of a glass appears to narrow as it nears your eye level, circles on a flat plane appear to become progressively narrower ellipses as they approach the horizon (eye level). The circles farthest away from you (closest to the horizon) will have the shortest minor axis; those nearest you will have the longest. Imagine water lilies on a pond. The water is a plane on whose surface the plants' circular leaves rest; leaves in the distance appear narrower (i.e.. have a shorter minor axis) than those nearby.
The minor axis of an ellipse is used to determine the plane's relation to eye level, forward-backward tilt, and distance from the viewer. The major axis is used to establish the sideways angle, or tilt, of the plane.
Here, the smaller, narrower ellipses give the impression of being in the distance, while the wider and larger ellipses seem close to the viewer. These shapes are arranged to imply a flat horizontal plane.
Water lilies are a good subject for observing how elliptical perspective works. The water is a flat plane on which the round leaves rest; with increasing distance, the leaves appear as progressively narrower ellipses.