Automatic Lighting Model

  All of the characteristics from Section 3 can be automated in a straightforward manner. Edge lines are drawn in black, and highlights are drawn using the traditional exponential term from the Phong lighting model [17]. In Section 4.1, we consider matte objects and present reasons why traditional shading techniques are insufficient for technical illustration. We then describe a low dynamic range artistic tone algorithm in Section 4.2. Next we provide an alogrithm to approximate the anisotropic appearance of metal objects, described in Section 4.3. We provide approximations to these algorithms using traditional Phong shading in Section 4.4.