Movie Render Queue - Render alpha channel for media plate and ignore fog and sky

0scar_0
Fri, 12 May 2023 00:12:38 +0000
Feedback & Requests

Hi there. I just want to make a request to allow for the Movie Render Queue to render stencil layers with the alpha accumulator enabled, as well as enabling alpha channel support in post processing but without having to remove fog or sky.

My main goal is in virtual production, where I would like to composite an EXR image sequence in Unreal Engine, render it out, and then edit the rendered EXR sequence in Davinci Resolve and be able to easily target my media plate actor in a layer.

At the moment, when I do this with the accumulator includes alpha and with alpha channel support in post processing set to “Allow through tonemapper”, the final rendered EXR sequence has non transparent colours in the specific stencil layer. Basically the areas with sky / fog are completely black and ugly in the rendered images.

I guess another way to say that is when I do all of this and render from UE, the final EXR render does not properly handle alpha in the layer with the media plate actor. If there is fog or sky in the background, then that will render as black and fully opaque.

Ideally I could just render the media plate actor out in its own layer, even with fog and sky in the background, and still only have my media plate actor on that single stencil layer, with everything except for the media plate actor transparent on that layer.

This would make it much easier to do colour correction in Resolve, because I can just target a single layer and do colour corrections on that as opposed to doing colour correction in Unreal Engine which is a huge pain in the butt.

I’ve shared a very flattering test photo of myself below which shows how the fog / skylight is in the same layer as my media plate actor. This is super annoying because it is even more work to select only the plate of myself and colour grade that.

Ideally the only content in that layer is the plate of myself and nothing else.

And below you can find another image where the accumulated alpha from the sky / fog completely destroys this render. If the sky/fog were properly handled with “enable alpha channel support in post processing” project setting set to true as in “Linear color space only” or “Allow through tone mapper” selected then it would be much easier to color grade footage outside of Unreal Engine.

When the “enable alpha channel support in post processing” project setting is set to False or Off the render looks perfectly fine and is well lit and there are no black areas.

Hopefully I am clear and my request is understood by the UE Devs!

Any thoughts, comments to share?

Thanks.

3 posts - 2 participants