Autodesk 12812-051462-9011 User Guide 3 - Page 1025

Use Autovolume When on, uses the mental ray autovolume mode. This lets you render nested or overlapping volumes such as the intersection of two spotlight beams. Autovolume also allows a camera to move through the nested or overlapping volumes. Default=off. To use Autovolume, Ray Trace must be on, Scanline must be off, and the shadow mode must be set to Segments. (You set the shadow mode on the Shadows And Displacement rollout on page 6292.) If these conditions aren't met when you click to turn on Autovolume, an alert warns you about this, and gives you the option of making the appropriate setting changes. Raytrace Acceleration Group Method The drop-down list sets which algorithm to use for raytrace acceleration on page 8102. The other controls in this group box change, depending on which acceleration method you choose. These are the alternatives: ■ BSP (The default.) The BSP method has Size and Depth controls. See Ray-Trace Acceleration: Parameters for the BSP Method on page 6282. This method is the fastest on a single-processor system. Use it for small-to-medium size scenes (less than one million triangles) on a single processor. BSP is also the best method to use when ray tracing is turned off. ■ BSP2 The BSP2 method is configured automatically by mental ray and has no controls. This method is optimized for large scenes containing more than a million triangles. BSP2 requires less memory than BSP and is able to flush memory when necessary. However, there could be a small performance loss when using it with smaller scenes. Reflections/Refractions group Trace depth controls the number of times a light ray can be reflected or refracted. At 0, no reflection or refraction occurs. Increasing these values can increase the complexity and realism of a scene, at a cost of greater rendering time. 6280 | Chapter 20 Rendering