Maya 2012 Unified Sampling in mental ray


Hey David, whats up!

Not to revive an old thread but I’m looking at doing some pfx grass and wondering if it could get the same benefit from unified sampling as fur?

If so, where do I access the controls for US, and for turning progressive rendering on in 2012? You know me, I’m so not technical…



Look here:

Hair and fur should be faster in 3.9 I know hair and fur are an area of concentration for everyone lately. So I expect further enhancements.

The image is geo but you should be able to get good anti-aliasing with fur.


Sure looks pretty, how do I get it going ?


The beginning of this thread explains that. :wink:


So there’s no GUI at all at the moment, you can only enter MEL commands?


The mel will automatically add the String Options.

You can get to those (once created) by selecting the miDefaultOptions and going to the string options rollout. (Use the “select by name” box and type: miD* ) I just make a mel shelf button.

From the rollout you can change the settings in UI however you like.

There is an enjoyMentalrayStringOptions script with this built in but you have to be careful with it because the options are destructive for indirect lighting.

Feel free to press Autodesk for implementation. . . .


Really useful information here, thank you all for your examples and amazing patience.

Again Bitter great job, you have saved me a bunch of time! :slight_smile:


I have been playing around with unified sampling for the last week in production and am blown away by it’s ability. I absolutely love it. However, I noticed that although unified sampling kicks adaptive’s method in butt, it seems (I could totally be doing something wrong) that is doesn’t do a very good job with edge quality. Note the quick render below, the adaptive method has a lot smoother line quality, where with the unified, it’s much more wavy and seems to eat into the alpha (the border edge shrinks a pixel or so between adaptive and unified). This is true even if I crank the unified quality settings to 2 or 3 or even if I bring up the min samples to 30. So far it hasn’t been an issue at all, I was just curious why this happened and if there was a way to get nice clean edges with the unified sampling method.

Thank you again for this amazing thread and all the hard work that has been put into it.


We’ve mentioned this a few times:

mental ray 3.9.1 in Maya is an older version of Unified Sampling

The edges were corrected in 3.9.2. So current Softimage and Max versions have the improved Unified sampling.

Maya does not; a fact I’m sure is not lost on Autodesk. . .


Crazy. Thanks for all of your amazing knowledge, David. It is much appreciated!


David, thanks for posting this. Great info and really looking forward to trying this on some new scenes. Your blog is a great read too… Cheers mate



Hey guys,

Just wondered what are some typical things which would make the render times longer than without US ?
(you know, even if the US settings are low pre-view type of settings)


I started using Unified Sampling recently and it really saved me on a couple of times.
Big thanks guys :slight_smile:


Just wondered what are some typical things which would make the render times longer than without US ? (you know, even if the US settings are low pre-view type of settings)

Passes that are setup incorrectly like vector passes connected as color can severely slow down Unified Sampling. Vector passes can have values that are very different from one sample to the next. This makes Unified Sampling sample a lot. . .

Vector passes should be connect as ‘vector’ (obviously) to avoid this.

That’s usually the most seen culprit of seemingly slow Unified Sampling.


Much appreciated.
I’m just finding it slower, although more convenient just not actually rendering any quicker.

Side note:
Only as a quick suggestion but perhaps on your awesome site, if you had time, you could bullet point what you’ve found so far as to cause rendering congestion ? :smiley:
I’m just finding bits of info on threads/forums here (usually from what you’ve said) and there but I’m sure I’ll get it over experimenting for the next few weeks. Just that it’s frustrating as loads of other people are saying things are faster :shrug:


I will probably go more into optimizing scenes by looking at the output in awhile.

Have a couple things planned first but it’s on the list. The problem is there are so many random things that can cause render slowdown that it’s hard to feel like I’ve hit all the major permutations.


How came i get rid of the Unified Sampling altogether from showing up when I open maya? When I delete the strings and save, then re-open my scene, all the strings are back.

Is there a way to just get rid of them without having to keep going into my miDefaultOptions and clicking delete for each one?


Couple things:

Are you using a script that might restore them? Like the Native UI integration?

Are you saving it after deleting them?


Save the scene without the strings.

it saves the settings by scene.


It depend about what you use to integrate string options.