Autodesk 12812-051462-9011 User Guide 3 - Page 312

When Use Color From Other Materials is on, this setting determines the ratio between the standard AO functionality with Shadow Color set to black and the color bleeding from other materials. For example, at the default setting, RGB=0.2, 20 percent of the AO shadow color is derived from black and 80 percent is derived from the color of the nearby material. If you set Shadow Color to RGB=0.0 (black), then 100 percent of the shadow color comes from nearby materials. If you set Shadow Color to RGB=1.0 (white), then 100 percent of the shadow color comes from black; this is the same as turning off Use Color From Other Materials and setting Shadow Color to black. Custom/Global Ambient Light Color You can specify a color for the ambient light used in AO, or use the global color specified on the Environment panel on page 6689 > Common Parameters rollout. This parameter is used for doing more traditional AO; that is, supplying an imagined "ever-present ambient light" that is then attenuated by the AO effect to create shadows. While traditional AO is generally used when rendering without other indirect light, you can also combine it with existing indirect light. Bear in mind that this "ever-present ambient light" is inherently non-physical, but can possibly help lighten some troublesome dark corners. Round Corners group This effect rounds off corners and straight edges as a rendering effect only; it has no effect on geometry. The rounding effect happens to convex corners and surfaces that actually intersect. Concave corners that merely touch will not display the effect. To get the effect to work in concave corners the objects must be pushed into each other a little. The effect is intended for straight edges and is not guaranteed to work properly for highly curved, complex intersections. Round Corners When on, rounds off corners and straight edges at render time. Fillet Radius Specifies the radius of the filleted corners and/or edges. Blend With Other Materials By default, the rounding effect happens only between surfaces of the same material, but if you turn this on the filleting is performed against any material. In the following image, the molten chocolate is rounded off against the submerged objects even though they use different materials. In actuality, the molten chocolate is a completely flat plane. mental ray Materials | 5567