framebuffer/pass name to RGB(A)

[cesboa]

Hi. Is it possible to force mental ray to write passes out as RGB and not as the pass name. Just like Vray does it. I always render out seperate exr files pr. pass and it's annoying always having to shuffle the channels in nuke or using proexr in AE. It could be a hidden render flag or an oversight in the Render Globals to enable this option?? Thanks!

[Remydrh]

Inside of Maya there is the option to use a custom name for passes. It's found under the common tab.

File Output -> Frame Buffer Naming

[cesboa]

Thanks for your reply Remydrh, very usefull
But I'm looking for a way to make RGB channels for passes, if I change the name it doesn't produce RGB but eg. for AO it creates AO.R, AO.G, AO.B. I have created an ugly workaround by creating an post render script that converts the channels by coping an exr to exr with imf_copy, it takes the pass channel names and make them RGB. Again I'm always rendering single files pr. pass so there will be no conflict on which pass should own RGB
Do you follow my trail of thoughts?

[Remydrh]

I am, but I am unsure why you're doing it in that way. In Maya you could technically have shaders write to a channel of say, a surface shader, and generate an RGB where each of those channels holds different information. I have done that with matteshadow for example.

Or have shaders write to the same custom pass as long as their outputs were correctly set to be R G or B. This way when written to the same pass you will have each channel be correct.

Is there a specific reason you want that? Seems needless complicated to have to shuffle out that many channels in post.

mental ray often omits some types of workflows in favor of something basic but flexible. If you choose the flexible option you have many choices, but they require setup.

[cesboa]

@Remydrh
Thanks for your reply
I don't think I was clear enough in what I looking for. It's exactly the less complicated shuffle/converting in post I want. In MR default passe's RGBA are empty (except for Master beauty) so everything has to be shuffled or converted (extractor in AE) to use the passes. In vray there is an option to write passes to RGBA and it makes the workflow much easier when view and use files in RenderView, nuke, osx preview, AE, PS etc. I was hoping for a MR string option or an checkbox in the renderPass node under options (something like "use RGBA for output").
I totally agree on flexibility must be first priority, but this one IMHO is pretty straight forward and could just be an option hidden somewhere
A few examples on why I want the passes to be in RGB and not pass.RGB
- In AE all passes has to be converted used the extractor which creates a precomp, if the render sequence has to be extended it's not just done overwriting the images, every precomp has to be manually extended. When it's RGB there is no need for converting and therefore no need for extractor precomps.
- I can view all passes directly in the RenderView to double check everything is correctly (I have extended the RenderView with a pass dropdown), The RenderView can only view RGBA so passes that are not RGBA I have to viewed in imf_disp or DJV to be validate/viewed.
- In nuke the postage stamp is not black, and I don't have to shuffle to use the pass (depending on the pass of course).
For now I must live with my post render image convert script which have saved a lot of time.
Again thank you for your replies, it's a great help!

[steve]

Is it possible to force mental ray to write passes out as RGB and not as the pass name.

Yes. If your scene has only a primary "beauty" frame buffer and no secondary buffers or "passes" then it writes out this buffer as RGB channels without a "layer" prefix into .exr. As soon as you add "passes" carried in "user" buffers then .exr files require to write them out with an individual prefix.

Best, Steve.