it seems that along with new hair shading, the recent Mental 3.12 coming with SI 2015, also (finally) has a new speedy & non blotchy GPU + reasonably quick CPU GI rendering (!)
An easy (on or off), accurate, yet usable-y fast and stable (in animation) method,
which was something that was sorely missing OOTB since forever,
but particularly since Arnold (SItoA which came for SI first for some reason )
https://elementalray.wordpress.com/2014 ... ick-start/
Has anyone tested? (using string options? (see below))
As for current prototype limitations::
The MotionBlur and CutoutOpacity (if they mean alpha cutouts(?)) seem to me like the biggest ones,As such there are some limitations to know about in this prototype:
- Motion blur not supported
Lens shaders not supported
Hair is tessellated
Visibility (cutout opacity) not supported
Specular interaction currently handled by Final Gather
but hopefully a more finished version would make-it before the last SP.
If it may be of help, I included the string options which are from here,
and you can install Mental Ray String Options
from RRay's magic bag of tricks
if you want to give it a whirl and perhaps post results(?) (StringOptions Addon also by RRay himself )
Î think 'off' is new GI algorithm still on, but with GPU acceleration off, and Sampling is probably through Unified Sampling settings.Global Illumination GPU
This version of mental ray offers a GPU accelerated implementation of global illumination effects.
In this initial form, the GI GPU mode speeds up indirect illumination through diffuse bounces of light, similar to what final gathering typically computes.
The GI GPU acceleration can be enabled and controlled with string options and on the command line of standalone mental ray.
For Global Illumination GPU rendering, these new string options are supported:
"gpu gi" "on"|"diffuse"|"off"
The values are:
"on"
for general GPU acceleration enabled.
The diffuse paths are computed on the GPU, specular sub-paths are computed on the CPU.
The performance gain compared to CPU rendering is moderate, however the rendered images are of superior quality.
('superior quality' from NVidia being a GPU company, so to be taken with a grain of salt ;] )
"diffuse"
GPU acceleration is enabled, but only diffuse paths are computed.
Performance gain is dramatic, however some scenes may be darker due to missing illumination from light paths through specular bounces.
"off"
GPU acceleration is disabled.
These are also new:
To enable and tune the new Unified Sampling Filter scheme, a new string option is supported:
"unified sampling subfilter" on|off
To enable and tune Global Importance Sampling, these string options with new values are supported:
"light importance sampling" "on"|"all"|"local"|"off"
The values are:
"on"
Enable light importance sampling across all area lights in the scene.
"all"
Enable light importance sampling across all area and point/spot lights in the scene. This is useful for scenes with large number of point lights. However, for scenes with one or few point lights, the value "on" is recommended.
"local"
Importance sampling is applied to each light individually, with no cross-balancing among the lights. This corresponds to the light importance sampling performed in the previous version of mental ray 3.11.
"off"
Light importance sampling is disabled. This is the default.
The following options are available for further control:
"light importance sampling quality" numscalar[numscalar]
"light importance sampling precomp" on|off
"light importance sampling resolution" numint
cheers!