EXR problems in Maya 2009

[scorpes]

Hello, i can't find a way to render passes in maya 2009 to separate floating files?
I can render everything to a multichannel EXR, but that makes my file very slow to handle in Nuke. So i want a exr for every pass, but then it still writes the passes inside the channels in the exr, I just want the passes as RGB and not in the channels, so I can also use them for flame instead of nuke.
Also I don't know if this is possible, but also a solution for me is to write out 3 different Multichannel EXR's at the same render? A single Beauty EXR and a EXR for the diffuse, reflection, spec, refr etc, and a EXR for the extra passes like Zdepth, Normals, mattes.
Do you guys know any solutions?

Gr Robbert

[mclausch]

In the "Common" tab of the render settings you can right click on the "File name prefix" field to insert special tokens that are translated at render time.

To solve your first problem you can insert the <RenderPass> token which will cause the pass name to be inserted into the output file name. This will force separate EXR files for each pass (where each file will have the pass name as part of the file name).

To solve your second problem, you can use the <RenderPassFileGroup> token. It will cause the "Pass Group Name" to be inserted into each file name, thus creating a single EXR for each group. You can set the "Pass Group Name" on each pass in the Attribute Editor for that pass. Every pass that has the same name will end up in the same EXR file.

Matt

[mayanic]

yep - that's the answer.

i think it's the better way to go with separate files. we all render out image sequences out of our 3d packages to avoid the loss of all files in case the render fails. And now i spent 2 or 3 days to push passes in one file instead of going with multiple files / file sequences.

hehe

[scorpes]

hey thanks for your reply, mclausch.

Cool RenderPassFileGroup works great!
One question still remains, if i want to render everything to seperate passes, then i put <RenderPass> into the filename, but then it put's the passes inside the channels instead of putting it into the RGB. I want the passes in the main RGB, is that possible?

[bart]

Please clarify what you mean. I'm confused, as this seems to contradict your first post.

Do you consider all color components (R, G and B) as going into a channel?
You can choose what type of data is written to a pass such as rgb color, or a scalar.

By separate pass, do you also mean separate exr file?
You can write passes to different exr files or to the same exr file, or group them to several exr files.

[mclausch]

One question still remains, if i want to render everything to seperate passes, then i put <RenderPass> into the filename, but then it put's the passes inside the channels instead of putting it into the RGB. I want the passes in the main RGB, is that possible?

Please clarify what you mean. I'm confused, as this seems to contradict your first post.

I think the problem he's having is that even when the passes are separated out each into its own EXR file, the EXR channels are not named R, G, B, but instead have the full Maya pass name (thus causing problems with various post applications).

The OpenEXR implementation in mental ray seems to force the channel names in the EXR file to match the framebuffer name defined for mental ray. I'm not sure of a way around this problem, but maybe Bart knows.

Matt

[mayanic]

sorry that i interfere . . .

mental ray puts the render pass name as a prefex to the channel.
so when you read your files in fusion you get several passes with each channels in one file (reflection.R, reflection.G, reflection.B, reflection.A . . .).
that would be great for orientation but fusion - so far - doesn't show you the mapped pass within the flow.
and - you have to adress each and every aux channel manually, what is very anoying as well.
but that's an other story.

[andy.jones]

Reviving this thread, as the problem has come up on two shows in a row now, in separate packages.

So, I can confirm that this is a major problem with standard Mental Ray output, as support for named channels in exr files is still lacking in many compositing packages. Bart, to clarify, we're not talking about individual data channels (R, G, B, A, Z, etc). But rather, the named groups of channels that show up in exr files, such as "Diffuse," "Depth," "Specular," etc.

In my case, I'm having to deal with this issue with AfterEffects. There's a plug-in that allows you to read named channels from an exr, but it causes the file reads to be much slower than the built-in exr reads. (Disclaimer: I am endlessly bothered by AE for this and a thousand other reasons, but I've learned that no matter how hard I argue against it, AE and its backwards ways will not go away). Even in Nuke, which handles all this stuff extremely gracefully, it's bad to be forced into a particular multi-layer workflow. Although a lot of people swear by Nuke's multi-layer flows, not everyone is a fan, and they do tend to be a little buggier, especially if you haven't spent a lot of time with them.

In Softimage, the issue is usually avoided, as the output is written using an output shader. So that might be one possibility for people struggling with this issue in Maya. Currently, the problem I'm facing is that enabling stereo rendering has forced me back to the standard Mental Ray framebuffer output, which puts me right back where you guys are with Maya. So now I'm probably going to have to write a special output shader just for the purpose of handling stereoscopic output, just because there's apparently no way to disable the exr channel labeling feature.

I think the solution is that we need a framebuffer option to be able to explicitly set the name of the exr channel being written to, or set it to the primary rgba. Given the degree to which people are standardizing around exr, this seems reasonable to me. Perhaps an even better solution would be a way to have something like string options for output statements, so that we could provide specific options for different file formats. But simplicity is also good

Incidentally, anyone know if there's a well-defined way to check from an output shader whether it's being called for right or left eye? I think I'm going to need to do that, and I'd prefer to avoid anything hacky, like using persistent counters.

Thanks!
- Andy

[Mantis]

Any news about this?
I'm facing the exact same issue with maya and mental ray.

[vetoPWR]

Bumping this thread again.

Has there been any changes introduced to aid us in writing user fb to individual exr files? I'm sure I could come up with some kind of channel shuffling routine, but it would be preferable that either ADesk or Mental took an interest in feature requests or bug fixes this time.