The illusion of form is created by the transitions of value from the darkest areas to the lightest areas. We will see a prismatic form if the light area is sharply divided form the dark area. A softer transition will create a rotund form such as a sphere, cylinder, ovoid or cone.
The rate of transition is determined by the diameter of the object, the larger the diameter the softer the transition. The "Banding" of the transitions is controlled by the relationship of the object to the illuminating source.
For our purposes we will investigate the effects of five different angles of illumination on both a sphere and a cylinder. This will provide us with a basic understanding which we can apply to more complex situations.

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