The primary interface to the mental ray renderer consists of rollouts on the Render Scene dialog. You must use the Assign Renderer rollout to choose the mental ray renderer, as described in this procedure.
In addition, object properties, lights, and the Material Editor have additional controls to support mental ray rendering.
Several new parameters have been added to the mental ray panel of the Object Properties dialog. These options support the mental ray indirect illumination features of caustics and global illumination.
Along with the mental ray renderer, new area light objects and new light settings are provided.
Area lights are a feature of the mental ray renderer. Instead of emitting light from a point source, they emit light from a broader area around the source. There are two mental ray area lights: mr Area Omni Light and mr Area Spotlight. Area lights create soft-edged shadows. This can help improve the realism of your rendering.
Note: To render soft-edged shadows, shadows must be ray-traced, not shadow-mapped: see the Renderer panel > Shadows & Displacement Rollout.
In Autodesk VIZ, area lights are created and supported by the MAXScript scripts, light-mentalray_areaomni.ms and light-mentalray_areaspot.ms. Both scripts are found in the \stdplugs\stdscripts\ folder within the program install directory. Because of this, when you create an area light, you actually create a target spot or omni light for which the mental ray renderer uses the parameters on the Area Light Parameters rollout. If you render with the default scanline renderer, the light behaves like any other target spot or omni light. (You can change a light from one type to another using the Type drop-down list on the light’s General Parameters rollout.)
For area lights rendered with the mental ray renderer, you can still set and use other lighting parameters, such as color, the Multiplier value, the spotlight cone, and so on. Shadow maps are an exception. The mental ray renderer ignores the light's local shadow map settings. Area lights always use ray-traced shadows.
Tip: You can use a MAXScript utility to convert standard Autodesk VIZ light objects to area lights, as described in this procedure.
The mental ray Indirect Illumination rollout has been added to light objects to support the mental ray renderer’s indirect illumination effects of caustics and global illumination.
The mental ray Light Shader rollout has been added so you can add mental ray light shaders to light objects.
Important: To see the mental ray rollouts for lights, you must use mental ray Preferences to enable mental ray extensions. These rollouts appear only on the Modify panel. They don't appear on the Create panel.
On the Parameters rollout, a “Depth Of Field (mental ray)” choice has been added to the Multi-Pass Effect drop-down list to support the mental ray renderer's depth-of-field effects. To use this, turn on both Enable in the camera's Multi-Pass Effect group (default=off), and Depth Of Field on the Render Scene dialog > Renderer panel > Camera Effects rollout.
You can also assign mental ray lens, output, and volume shaders to cameras. These controls are also on the Render Scene dialog's Camera Effects rollout. (This rollout also contains some contour-shading controls.)
Note: When you use the mental ray renderer, reflected or refracted light rays do not always respect a camera's clipping planes (set in the Clipping Planes group of the Parameters rollout). Also, large clipping-plane values can cause poor quality in the rendering of shadow maps. To fix this, narrow the clipping range or switch to ray-traced shadows.
The Material Editor works as it does with the default scanline renderer. Certain materials and maps, or some of their controls, aren't supported by the mental ray renderer; see Autodesk VIZ Materials in mental ray Renderings.
By default, the Material Editor sample slots use the currently active renderer: typically this is either the default scanline renderer or the mental ray renderer. As of Autodesk VIZ 2005, you assign the renderer for sample slots by using the Render Scene dialog > Common panel > Assign Renderer rollout.
When mental ray extensions are enabled (using mental ray Preferences) and the mental ray renderer is active, the Material Editor displays these additional mental ray features:
A mental ray Connection rollout lets you add mental ray shaders to Autodesk VIZ materials.
When you click a material's Type button, the Material/Map Browser displays additional mental ray materials.
When you click a map or shader button, the Material/Map Browser displays additional mental ray shaders.
Shaders are provided in shader library (MI) files. Some shaders are customized for Autodesk VIZ, some are provided by the lume library, and most are provided by mental images libraries. Settings for the custom Autodesk VIZ shaders are provided in this reference. Settings for the third-party lume and mental images shaders are provided in their own help files. This reference links to those descriptions; see Shaders in the LumeTools Collection and mental images Shader Libraries.