Autodesk 12812-051462-9011 User Guide 3 - Page 315

Color at Max Distance When on, the material simulates physically correct absorption. At the distance specified by Max Distance, the refracted image has the color given by Color At Max Distance, but the rays are not limited in reach. At twice the distance, the influence of Color At Max Distance is double, at half the distance half, etc. When off, transparency rays simply fade to black. This is like smoked glass and other highly absorbent materials. Transparency just stops at the specified distance. This has the same performance advantage as using the Max Distance for reflections: Tracing shorter rays is much faster. Available only when Max Distance is on. Left: No limit (Max Distance=off); Center: Fade to black; Right: Fade to blue Max Trace Depth When this trace depth is reached, the material refracts black. Cutoff Threshold The level at which refraction is rejected; that is, not traced. It's a relative value: For example, the default setting of 0.01 means that rays that contribute less than 1 percent to the final pixel are ignored. A setting of 0.25 means that mental ray discards rays that contribute less than a quarter of the value of the final pixel. Advanced Reflectivity Options group Visible area lights cause no Highlights When on, mental ray area lights (Omni on page 5070 and Spotlight on page 5073) with the Show Icon In Renderer property on create no specular highlights. Default=on. The Show Icon In Renderer check box is found on the light's Area Light Parameters rollout. When on, the light is visible and reflects in any glossy, 5570 | Chapter 19 Material Editor, Materials, and Maps