mental ray for Maya 2016 SP1 is now available for download here.
It ships with mental ray 3.13.1.8. Both the mental ray core and the integration provide important fixes that we will list in this post.

MDL rendering: latest MDL fixes are incorporated into SP1.

The new version of the MILA layering shaders fixes various issues:

• alpha channel computation for specular and glossy transmission
• possible texturing artifacts if mila_light light shader was used
• halo effect on specular highlight when using mila in IPR
• possible black pixel artifacts / NaN warnings in custom curve layer weights
• unknown tag access fatal if mila_specular_transmission was used in combination with irradiance particles or with the GI Next prototype
• missing subsurface scattering effects behind refractions
• possible issues with semi-transparent objects in segmented/sorted shadow modes
• possible tile artifacts in particular with glossy reflection mix
• VP2 display for mila is now also working for scenes created with Maya 2015

UV-tiling: There was a severe bug around uv-tiled textures and conversion to .map textures: the conversion to .map would sometimes be automatically triggered. This is fixed now. The conversion will only occur if ‘Use optimized textures (auto-conversion)’ is checked in the rendering preferences. (There is a known issue in this context: the button ‘Update optimized cache textures now’ only converts the first uv-tile of a uv-tile sequence. The others will be converted during the first rendering.)

Also, when you created two file texture nodes both referencing the same uv-tile sequence, this could lead to a crash with the previous version. This is now resolved.

There are also various performance improvements in the SP1 version:

• Since Maya2016, the new shadow mode default is “shadow segments”. This mode supports all ray tracing effects including subsurface and volume scattering in contrast to the approximate, thus potentially faster “simple” shadows. With the latest mental ray, we have improved the performance of “shadow segments” on scenes with extremely high depth complexity.
• Light Importance Sampling is now faster for scenes with a mixture of large and small are lights.
• Mental ray render times with procedural shaders/textures (ocean, fractal, and so forth) are also improved.