Movie render graph - Hold out issue

Development Rendering
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Hi,

I am trying to use the Movie render graph to separate layers (Background, subject, foreground).
The issue I’m encountering is that when I mark anything as a holdout, the layer that renders is transparent and the skies end up black. I am not sure what is causing this.

I’m using Ultra Dynamic Skies for my skies and light. I just want to state that in case that is the culprit.

Any help would be appreaciated.

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Hi there, setting an Actor or a collection to have Holdout on will produce exactly the result you got here, this isn’t a bug. Holdout is meant to act as a stencil in your render. Wherever an actor that is set to Holdout is visible to the camera, it will set all 4 channels of your output image to 0 - RGBA will all be empty. If you have an actor that is not set to holdout in front of one that is, that actor that isn’t set to holdout will be visible as normal.

I’ve linked to a part of this video talking about Holdouts -

Holdouts in Unreal Path Tracer

https://youtu.be/P4bUMPwxFu8?si=r4vDj_kfB7Xhwzh9&t=2845

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I have not gone through everything in the UDS. But make sure whatever is in there actually has a holdout parameter on the actor. If there are a bunch of components you may have to go get at them individually to set their holdout attributes.

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Thanks for getting back to me on this, Shaun. I’ll give that a shot and see if it solves the issue.

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I’m running into this issue currently.

All the components of UDS that I’m using have the holdout parameter, but it doesn’t seem like it’s being set when I enable the holdout on my MRG modifier. It seems like it’s not getting passed down. I tried to create a component group to create a collection with just those components of UDS, but it doesn’t seem to work on them, it only works on the main UDS actor.

I can manually change them all to holdout in the sequencer, but that’s no fun and kinda kills the point of the MRG. Is there any way to get at the holdout parameters of the sub-components of UDS, or whatever those are called?

Is the MRG designed to pass the holdout parameter down to the child components if it’s available?

Edit: I think it’s working as I was hoping, I seemed to have one of my collections set to subtract by accident instead of add.

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