Collection Ray Visibility

Cycles Development
#1

Hello devs, since we already have Indirect Only for Collection in Cycles ( which is in my limited understanding was something like Camera Ray visibility )

Is it possible to expose the other Ray visibility for collection ? Like shadow, in my case I need a shadow matte pass only from characters, not combination between characters and environment.

This might be feel as a feature request, but I feel that Indirect Only already does the job for excluding Camera ray visibility, which is could be extended for other rays, isn’t it ?

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Thanks

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#2

It’s relatively trivial to create a material that is transparent but casts shadows. Cycles now supports AOVs, so I wonder if there is also an AOV solution to the problem you’re trying to solve?
Anyways, per-collection ray visibility that can be overridden is something I would love to see.

#3

afaik Cycles Shader AOV only works with Color and Value input, it can’t be used to override the object’s material and control light path ray.

For example I want to override material for all objects under Environment collection, I need to give all the materials a light path node, transparent shader and mix them with their original shader network so I can get cast shadow to be off, but this is going to affect all the materials for objects under this Environment collection whatever Scene I’m working on, which is not something I want.

In my case objects under Environment collections can be thousand objects that linked from another library, my screenshot above is only simplified example of what I usually did for separating collection in shot production, which I always miss this ray visibility option for collection.

#4

I’d be happy to try and assist with a workaround… but I don’t want to turn this into a help thread if you meant for it to be a discussion about a feature (which I agree is a good idea). Feel free to DM.

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#5

Thank you for your willing to help with workaround, my current workaround was to do this in compositing, which I need to subtract the shadow pass with environment shadow pass so I can get only shadow from characters. I’m ok with that for now.

#6

Could this also address the possibility of lights affecting only the collections they’re in? This would be extremely useful for my workflow. Having the possibility to tweak the light just a bit in certain areas instead of creating whole new layers would be amazing.

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#7

That is going to be different thing, probably light linking is what you want, this feature is on the dev list, so we can expect that is in progress

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#8

That’s great news. Thank you!! :slight_smile:

#9

Hi, did you find a solution? I am on the hunt for a way to turn of rays to the camera on certain collections. To make a full shadow render, for post processing. Can’t find a way to change this on multiple object anywere.

#10

Unfortunately, for the sake of simplicity I decided to do full beauty render without shadow pass, the compositing method that I used before is not really helpful on some cases and require quite complicated setup for our artist to work fast.

Perhaps if you really want to have shadow pass, you need to duplicate the whole scene and then turn on shadow catcher per object on the collection where you want only the shadow, however just be aware that the objects on that scene is basically new object, which is if you update the other scene, it will not reflect on that duplicated scene.

Anyway I still think Blender needs this collection ray visibility, I saw something similar on all other lighting packages out there, it is really make life easier to setup shot lighting.

#11

If you only need to turn off camera ray per collection, you can turn on indirect only of the collection, it will not render the objects inside that collection, but you will still be able to see the other rays such as shadow.

#12

Thanks.

I made a script (with the help of the guys at the Blender Discord channel) that turns off/on “camera rays” on everything inside a Collection. That solved my problem.

Skärmavbild 2022-04-26 kl. 10.06.32

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