Autodesk 12812-051462-9011 User Guide 3 - Page 340

Stone would have a very low Reflection Glossiness (lower than 0.25) and one can most likely use Highlights+FG Only to good effect for very good performance. Use a nice stone texture for Diffuse Color, some kind of bump map, and perhaps a map that varies the Reflection Glossiness value. The Reflectivity would be around 0.5-0.6 with By IOR (fresnel reflections) off and 0 degree reflectivity at 0.2 and 90 degree reflectivity at 1.0 Glass Glass is a dielectric, so By IOR (fresnel reflections) should definitely be on. The IOR of standard glass is 1.5. Set Diffuse Level to 0.0, Reflectivity to 1.0 and Transparency to 1.0. This is enough to create basic, completely clear refractive glass. If this glass is for a window pane, turn Thin-walled on. If this is a solid glass block, turn Thin-walled off and consider if caustics are necessary or not, and set Refractive Caustics accordingly. If the glass is frosted, set Refraction Glossiness to a suitable value. Tune the Refraction Samples for good quality or turn on Fast (interpolate) for performance. Colored Glass For clear glass, use the tips in the preceding section. Colored glass, however, is a different story. Many shaders set the transparency at the surface of the glass. And indeed this is what happens if one simply sets a Refractive Color to some value, such as blue. For glass with Thin-walled turned on this works perfectly. But for solid glass objects this is not an accurate representation of reality. The scene in following illustration contains two glass blocks of different sizes, a sphere with a spherical hole inside it, and a glass horse. NOTE The spherical hole was created by inserting a second sphere with its normals flipped inside the outer sphere. Don't forget to flip the normals of such surfaces or they will not render correctly. mental ray Materials | 5595