ABSTRACT
CHAPTER 5 COVERS VARIOUS techniques for rendering semitransparent volume surfaces using an approximation to the Blinn-Phong local surface shading model. Although this model is adequate for shading surfaces, it does not provide sufficient lighting characteristics for translucent materials or materials where scattering dominates the visual appearance. Furthermore, the normal required for the Blinn-Phong shading model is derived from the normalized gradient of the scalar field.
