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View Full Version : MR/Software differences: light fog, duplication

Sandstone
05-23-2005, 12:22 AM
Howdy - having just purchased Maya Unlimited 6.5, I've been absolutely stunned by it's power, beauty, and... complexity. :) I have two images below - one via Maya's software renderer, and one via mental ray. The light fog that appears in the Software version took lots of crafting - and it doesn't even show up in the mental ray version. Why is that? In addition, the column (which is a duplicated subdiv converted from a polygon object) only shows up once in the mental ray shot, and five times (as it should) in software. Lastly, there's an odd square kind of thing under the single column in the mental ray image.

What causes these? I know that this is mostly an experience thing, and I'm looking forward to gaining some of yours!

Software render, Preview Quality preset:

http://sandstone.brewsters.net/images/softwareBB.jpg

mental ray render, Draft preset:

http://sandstone.brewsters.net/images/mentalrayBB.jpg
Bonedaddy
05-23-2005, 06:46 AM
Light fog's a maya software post-processing thing. Mental Ray volumetrics are wholly different from maya software. It gets pretty complicated, actually.

Mental Ray subdivs are weird. It won't render unless the base mesh is all quads. I don't know what you did for duplication, though. Is it instanced? Straight duplication? Particles? It could be a lot of different things.
Sandstone
05-23-2005, 04:57 PM
Interesting - so if I want to combine mental ray and light fog, it'll have to happen in two rendering passes. I'll try converting my pillars to all quads and see what happens - they were created with straight duplication.

The reason I tried to use mental ray is so that I would get a reflection of the light fog in the water. I wonder how that would be accomplished, if the light fog doesn't even register in mental ray! I read that reflections have to be done in mental ray... true?

Thanks again for the help!
Bonedaddy
05-23-2005, 10:26 PM
No, reflections are not a MR-specific thing. MR reflections are better, and can be physically accurate, but Maya software does have reflections. You just need to tweak your water shader to reflect stuff.

However, since the glow is a post-process, I don't know if it'll reflect very well. You may need to toy with it for awhile. Basically, glows are drawn on top of the image after everything is rendered, and they have no real geometric density. Most glows are done in compositing , so if you run out a black-and-white pass of just the cloud and its reflection, and used that to drive the glows in compositing, that would probably be your best bet, and give you the most control. Multi-pass rendering is necessary for a scene of even intermediate difficulty. Rendering everything out in one pass is suicide.
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05-23-2005, 10:26 PM
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