The shifts in color and/or value of the planes indicate the turning of form. The planes might be compressed near the edge of a form, elongated in the direction of the edge, in order to indicate the turning away of the form from the viewer. The use of medium-sized planes generally requires a simplification of the forms being depicted, and the artist must make choices concerning which aspects of the form will be emphasized. The shape of each plane can be unique, or the artist can choose to limit herself/himself to a particular shape or set of shapes that will be used for all of the planes. For instance, only triangular shapes might be used, or circular, or rectangular, etc.
Medium-sized planes can also be used in purely abstract works that create the illusion of a three-dimensional abstraction.
Featured: Jean Metzinger by Robert Delaunay.