Scene Description Language

Multiple motion vectors are now possible, and may require changes to shaders that evaluate motion vectors. (Normally mental ray handles motion vectors internally but post-motion output shaders might exist that access them directly.)
A polygon vertex or free-form surface control point may have up to 15 motion vectors instead of only one. Multiple motion vectors define a path to allow curved motion blur. For motion transformations, a new motion steps option specifies the number of curve points to generate.
Shutter statements may optionally define two values, a new shutter delay value defines the shutter open time in addition to the standard shutter close time.
Two new types of area light source was introduced: one that uses any geometric object to define the shape of the light; and a user type that lets the light shader pick points on the light surface, and control integration in the material shader with .
A new hair geometry primitive was introduced that can efficiently render large numbers of hairs. Hairs are assumed to be small in screen space, in the range of one pixel wide or less.
The new fine approximation mode allows efficient tessellation of freeform surfaces and displacement to microtriangles, which allows extremely detailed displacement without the previous high memory demands. This works with all rendering modes, including shadows and self-shadowing, motion blurring, ray tracing, global illumination, etc. See page fineapprox for details.
The new sharp approximation feature controls the sharpness of tessellations, by controlling the facet normals.
New command-line options: -approx, -approx_displace, -bsp_shadow, -diagnostic finalgather, -grid_depth, -grid_resolution, -grid_size, -nomaster, -motion_steps, -samples with four arguments.
New options block statements: bsp shadow, diagnostic finalgather, grid depth, grid resolution, grid size, motion steps, pass, samples with four arguments, shutter with delay argument, traversal. Image type "rgbe" in camera output statements, pass chain in the camera, lightprofile shader parameter type, apply photonvol in declarations, light profile blocks lightprofile... end lightprofile, fine and sharp attributes in approximations, and the writable attribute for texture statements. mental ray can use writable textures directly for rendering; mental ray 3.0 required a separate non-writable texture statement referencing the same file name.
New image data types for RGBE (8-bit high dynamic range color data), and floating-point alpha and intensity channels including no-elliptic pyramid filtering for one-channel images. New image file formats IFF (Alias Maya), Radiance HDR, and HT (simple uncompressed HDR image).
Inheritance functions are deprecated (but still supported), and replaced with the more powerful traversal functions that have full control over all forms of inheritance, including flags and materials.

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