Artists use cross-contour lines to indicate the surfaces of objects. When lines are used to create mass in a two-dimensional artwork, such as a drawing, these lines can add a convincing sense of volume to the forms that are depicted. If the lines are drawn systematically and with precision, then the resulting "wire frame" drawing will appear as if it were drawn in space. Three-dimensional artists also take advantage of this technique, often using line to focus attention on the surface of their sculptural works by accentuating the movement and clearly defining the forms.
