Is there some trick to getting volume lights to work properly with MR in Max 2009? 

We keep getting bad results whenever there are objects in the scene along with multiple volume lights. 

Please see the attached images and Max file for examples.

MR-NoOBJ.jpg = Mental Ray with atmospherics only (no geometry).

SL-wOBJ.jpg = Scanline with a surrounding sphere object (similar to an enviro-dome). 

MR-wOBJ.jpg = Mental Ray with the same surrounding sphere object.

volume_light_problem.zip = Max Scene

Thanks,

Brittnell

	Attachment
12911_9EYyST9QIkj6Jqx1KGj9.zip

	Attachment

	Attachment

	Attachment

	Attachment

The Volume atmospheric effect isn’t really compatible with mental ray.  I noticed you aren’t using Final Gather or Exposure Control in your file.  Do you plan to at some point, or have another reason for wanting to use Mental Ray?  If not, stick with Scanline.

If you really want to use mental ray, you’ll have to use the Parti_Volume shader as a Camera Output shader.  Search in the Additional Help files to learn a little more about it, and I’ve attached a Word doc that explains the settings in a little more detail.

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

	Attachment
12935_6ES9DBZwfAHuhXTEehR4.doc

Thanks Chris,

That’s unfortunate, but good to know.

We use FG about 50% of the time, but we almost always use MR / A&D materials. 

I was hoping to avoid it, but I think we’ll probably render out the atmospherics on a separate pass (scanline with matte/shadow materials), then “fix it in post”.  ;)

I had read about the Parti_Volume shader some time back, but had “filed it away”.  If Max’s standard atmospherics aren’t really compatible with MR (and there are no plans to make them such), I’ll definitely be using your suggestion moving forward. 

Thanks again for the info and suggestion!