Occlusion renders are not writing to RGB channels in batch render mode

[rimcrazy]

I'm having a curious problem that I don't fully understand. I have a fairly simple animation of an atom that has been shaded with VRay materials. I'm using Maya 2017 SP5 and the latest version of Vray for Maya 2017. I have set up a render pass for Occlusion. I have specified my output format to be a 16bit .exr file. If I simply open the VRay frame buffer and render a frame the occlusion looks perfect. If I save from the FB to a file on my desktop I get what is expected for a .exr with data on all RGBA channels. If I try to render in batch mode however all I get is an alpha channel and no data in my RGB channels of my occlusion render.

This is the batch command I'm using:

"C:\Program Files\Autodesk\Maya2017\bin\Render.exe" -r vray -s 1 -e 2 -x 4096 -y 2304 D:\projects\sandbox\Barrows\Rad_MIS_Surgery\Maya\A tomicModels\TungstenAtom\scenes\TungstenAtomVray3_ Brem.ma

This same format works fine when I'm rendering the Beauty passes with AOV's embedded in the output .exr

I've attached some screenshots from loading the files into photoshop. One shows the file generated with a 1 frame render withing the VFB in Maya GUI mode. The second shows the alpha channel only when I do a batch render.

I would add that I just ran a batch render from the Maya GUI and it gives the same bad results as doing a batch render from the windows command shell. Again, if I do a single frame render from the Vray FB it renders perfect with everything in the correct channels.

UPDATE: Ok so no comments. Is there a way I can dump a log or look at something from a diagnostic way to help me get a clue on what the issue may be?

[yolov]

Would it be possible to share the scene so we can have a look? The batch command seems perfectly normal.
You can find the logs in your user's temp directory, named vray4maya_log.txt

[rimcrazy]

I can do that. Tomorrow I will zip up the file. I assume I send it to your support@chaosgroup.com email. I will mention the thread in the subject line. If you want me to send it a different way I can do that too. Thank you very much for your assistance as I've been stumped.

[yolov]

I can do that. Tomorrow I will zip up the file. I assume I send it to your support@chaosgroup.com email. I will mention the thread in the subject line. If you want me to send it a different way I can do that too. Thank you very much for your assistance as I've been stumped.

Yes, that would be fine.

[rimcrazy]

Hi Alex, you should have received the file. I was wondering if you have had a chance to look at it yet? Tnx.

[yolov]

Yes, looking into it now.

[yolov]

So far I'm noticing a few things.

The output image format in the scene is set to MultiChannel EXR. I'm not sure if Photoshop works with such images, or if memory servers it required an additional plugin to work with multichannel exr files. Otherwise it works fine for single-channel exrs. Are you using a plugin for reading multichannel files? I think something like https://www.exr-io.com/ was recommended at the time.

Saving from the VFB directly does things in a slightly different ways. For example, there's a few "save" modes in the VFB that you're able to choose when you click and hold the save icon - 1. save the current image channel to a single file, 2. save all image channels to separate files, 3. save all image channels to a multichannel exr. The 3rd option in the VFB should give the same result as doing a batch render when the image output is set to multichannel. What option are you using from the VFB to save the image when you noticed that it worked in your case?

The scene also uses a lot of Maya shaders, in particular the surface shader. This one is not fully supported in V-Ray, Well there is some "support" as far as V-Ray recognizes it, but it won't render as expected (the out color should work, but the rest of the parameters are not expected to work properly). It is usually recommended to use V-Ray materials. We usually recommend using an extraTex render element and plugging a VRayDirt texture in it. This is actually the most common way of making an occlusion pass with V-Ray. The workflow also works on the same layer, i.e. there's no need for a separate render layer just for the occlusion, as it simply adds an image channel that you can later extract and works by doing a single render.

Could you elaborate a bit more on your end goal with the occlusion pass? A separate occlusion channel to multiply by the beauty image? If that's so, you could give it a try with VRayDrit and extraTex.

[rimcrazy]

Well I'm a little confused with your reply but to answer some of your questions.
1) If you go into the hypershade and select delete unused nodes you will see all of the surface shaders disappear except 1 which is why I may be having the problem.
2) I have the exr plug in installed into photoshop and it works perfectly. I can send you screenshots from PDLayer if you wish but they look the same. I know that works with .exr files.
3) I'm compositing with Nuke which I know works with multichannel .exr files fine.
4) I am creating a occlusion layer to multiply against a composited beauty layer. I've always created AO layers in VRay with the following network and they've always worked. I don't understand the network you are talking about with an extraTex render element. I don't know what an extraTex element is as it certainly is not a Vray shader. If you could send me a screen shot of what that looks like I'm guessing this is my whole problem.

Thank you.

[rimcrazy]

Ok.... I just looked up Render Elements in your docs. Sorry, looks like I've wasted your time and clearly have been doing AO completely wrong. I'm using Render Elements for all of my other render passes but in looking at Extra Tex it is not clear to me how I add a VRayDirt node into this pass? Seems to me I'd still want a surface shader around to attach to if for no other reason set the parameters of the dirt node to what I want but then I assume I need to disconnect it and some how hook it into your Extra Tex but since there is no Extra Tex node in your shaders it's not clear how I attach it for a render. If you have a quick screen shot or just a short paragraph on how I set up an AO pass with Render Elements it would help.

Thanks
Phil

Alex,

I redid my scene in Maya 2018.2 and used the newer render manager not the old render layers. I set up, what I thought should work but occlusion is still not working. I just emailed you the file. If you could take a look at this perhaps I'm closer but obviously missing something.

Thank you.

[yolov]

I'll try and have a look at the new scene tomorrow or on Monday.
Until then - just a few notes:
The usually V-Ray workflow for an AO pass is simply adding an extraTex render element and connecting a VRayDirt texture to the extraTex texture input, nothing more.
You can still connect the dirt to the surface shader, but it will work just as any other shader having the dirt in its diffuse input (for example) and you would either need to do a separate rendering for that, while the extraTex happens with the main beauty render.

[rimcrazy]

Ok Alex thank you. I will look over my scene and see if I cannot fix it. You've given me enough info for me to see the errors of my ways. Let me look at it and if I'm still lost by Monday I'll post. Actually I'll post either way but I'm guessing you have more pressing issues with others and my issues seem to be self inflicted. I was basically stuck and did not know where to go from what I had. Like I said you've pointed me in the right direction so I should be able to figure it out from here. Thanks.

UPDATE: Ok I got it working so you don't have to do anything. Thank you for your assistance.

[yolov]

Good to know. What was the solution?

[rimcrazy]

The way you told me to do it. I was making it far more complicated than what I needed to do. I flip between Arnold for my instructional work as at the school I teach we only have generic Maya which ships with Arnold. For my freelance work I only use VRay. The manner in which AOV's are handled are significantly different between how you must do it with Arnold vs VRay and it was biasing my approach. I wish I could just use VRay for everything but alas, schools have no money and they only use Maya because they can get it for free from Autodesk. Sorry I ran you on a goose chase for my own ignorance. I really do try to RTFM and figure things out on my own before I reach for assistance but I had a mental block on this one and could not get past it. Thanks again.