View Full Version : Render Passes

12 December 2009, 03:00 AM
Do render passes only work with Mental Ray's shaders? If so, must I use mia_material_x_passes for it work? The passes are not working for me when using mia_material. I just get a blank render. seems either way, I can't manage to get a successful depth pass.

Any help would be appreciated. Thanks!

12 December 2009, 03:32 AM
render passes don't work with mia_material_x_passes as that would make too much sense. Passes only work with the maya Lambert/phong/etc.

That's one of the reason I switched to VRay.

12 December 2009, 04:09 AM
wow...that sucks. Vray's sounding good to me too right about now.

What about rendering a basic z-depth pass? any ideas?

12 December 2009, 08:17 AM
You can render a luminance-depth pass with MR. I've just been using workarounds lately; more control and predictability. Cute how a very expensive and powerful application can't simply do things that cheap and even free apps can do quickly and painlessly, but that's the price you pay for more control I guess.

One workaround I'm finding success with is duplicating your scene, setting all materials to black, and using environment fog and/or a simple fluid to mimic z-depth. This will only work in certain applications obviously, and isn't a great solution. I'm sure there are better ones out there.

This artist, for example, has no problems with z-depth in MR at all:

Ultimate Maya & MR Arch Viz Guide (

12 December 2009, 09:06 PM
I just read about that...using luminance-depth passes. The environment fog idea doesn't sound too bad either I guess.

You're right, it is odd that with everything Maya can do...there are still problems with something as simple as this.

Thank you for your input!

12 December 2009, 09:20 PM
Yeah, much like Social Intertia, Maya has developed it's own "Technical Intertia". All the things certain artist's want changed interfere with things other users may want/use/need, and vice-versa. And although Autodesk isn't directly to blame for the horrible mental ray implementation, fixing it is likely more difficult than starting from scratch at this point. I couldn't even begin to list all the bugs between Maya and MR. Some of it is certainly user error (or my own ineptitude), but some things simply don't work how they should.

A z-depth pass should be a one-clicker, just like it SEEMS to be in the Render Settings, on the very first panel. This used to work fine, but is somehow flawed or broken in 2009. Fortunately Maya is diverse enough to make workarounds possible!

12 December 2009, 01:54 AM
render passes don't work with mia_material_x_passes as that would make too much sense. Passes only work with the maya Lambert/phong/etc.

That's one of the reason I switched to VRay.

Really, I just worked on a show with render passes and the MIA_material_X and it worked. Sometimes we were not getting normals passes to come out, but the main contributions were working...

Along the same lines, how do you control the output directory of these passes... They don't seem to go where the other render layers end up... I'm using deadline to submit to a farm. Any ideas? In fact, I don't even see the contribution pass, only the beauty.

12 December 2009, 04:30 PM
I've never seen render layers with anything but Maya's materials work with Mental Ray. I stopped using MR so maybe post your workflow for the OP.

12 December 2009, 06:11 PM
Render layers work fine with mental ray. That's not to say it's going to be easy or painless, though. Here's a recent thread dealing with them (among many other features of MR):

Ultimate Maya & MR Arch/Viz Guide (

12 December 2009, 06:45 PM
You can get most of the passes you need with the mia_material's outputs.

Mental Ray got it right, Autodesk did not. To me, Maya's pass presets are by and large broken. The biggest flaw is the lack of RAW passes. For instance the Indirect pass gets rendered out with the color added to it and the diffuse pass includes shading. All that severely limits what you can do with them in compositing. Other passes like Direct Irradiance only work under very special circumstances unlike the Mia_Material's equivalent, Diffuse_Level.

It's not all bad news though. There is a lot of cool things you can do with Mental Ray that could actually make Mental Ray more versatile than Vray's set up in the future. It just requires a nice script ( to automatically sets things up for you and work around a major bug.

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12 December 2009, 06:45 PM
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