Non-photorealistic rendering techniques used in computer graphics vary greatly in their level of abstraction. Those that produce images such as watercolor or pen-and-ink are at a high level of abstraction which would be inappropriate for technical illustration. Using a medium level of abstraction like technical illustration helps to reduce the viewer's confusion by exposing subtle shape attributes and reducing distracting details. Adding interaction gives the user motion cues to help deal with visual complexity, cues that are missing in 2D images. A review of past research reveals that no one has created a 3D interactive environment that takes advantage of shape information given by line drawings and artistic shading, presenting the shape information without the confusion produced by the many lines in a wireframe representation or the limitations of Phong-shaded images.