Scene Description Language

• The samples collect statement, which sets the number of samples filtered by the rasterizer, now defaults to 4 (16 samples) instead of defaulting to a number derived from the oversampling parameters. The shading samples statement sets the number of shading points per pixel taken by the rasterizer.
• The hardware samples statement controls the supersampling and multisampling settings of the hardware renderer.
• The finalgather trace depth statement has another parameter to control the diffuse trace depth. The optional parameters are now finalgather depth reflection refraction diffuse sum.
• The caustic scale, globillum scale, and finalgather scale statements supply a scaling factor to the brightness of these effects.
• The finalgather presample density statement adjusts the number of finalgather points during finalgather preprocessing, as a correction factor.
• The colorspace statements, and their references in output and texture statements, control the color space (sRGB, CIE, etc) used for rendering, loading, and saving images.
• The compress modifier on output statements selects OpenEXR compression modes none, piz, zip, rle, or pxr24.
• The trace flag in instances and objects was replaced with separate reflection, refraction, transparency, and finalgather flags that follow the syntax of globillum. So does the shadow flag.
• The shadowmap filter statement in a light definition controls shadowmap filtering.
• A new variant of directional light can be specified by supplying both an origin and a direction, but not spread because that would turn the light into a spot light. A directional light with an origin does not illuminate points behind the plane defined by the origin and direction.
• The volume group statement in an object ties together all objects with the same object group number such that autovolume mode treats them as belonging to the same object with a single inside volume.
• The trilist toplevel element is an alternative to object definitions that allows very efficient definition of geometry consisting entirely of triangles.
• The nosmoothing flag in approximations turns off normal interpolation during fine tessellation.
• The contour and contour normal approximation modes were removed.
• The new command-line option -fb_dir S specifies a directory where mental ray can save frame buffer files while rendering. Frame buffers can be very large, and mental ray 3.4 has no upper limit on the number of frame buffers, so they are no longer permanently stored in memory but can be paged out to disk.
• Support for DPI information in IFF, TIFF, and JPG/JFIF image files has been added, by means of a new optional parameter in output statements.
• Light maps can now be created in arbitrary image types, using the following .mi syntax extension: writable color texture "texName" "texfile.ext" "type" [ width height ].
• Sequences of registry entries with mi statements to include shader declarations are now executed in the correct order.
• Color profiles have been introduced.
• In conditionals in the .mi input syntax, it is now possible to test whether a variable is defined using the syntax $?variable.
• mental ray can now use different final gather maps for each object to optimize the global illumination workflow.
• Options lightmap on | off | only and photonmap on | off | only have been added.
• The option -texture_continue can now be specified for rendering slaves in network parallel rendering.

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