AOV / passes workflow

Good Day. I come from a film vfx background and I’m looking at implementing UE in the pipeline, as are many others.
Is there a reference regarding how to set up AOVs, holdouts, object passes? I have not yet found one



Not being from your background, can you explain those terms? They’re way to vague to google…

Oh. Apologies, I thought there were more vfx people already looking at UE. AOV refers to the different layers of light including for example, specular reflection, diffuse reflection, transparency, sss, and emit layers. Normally we render them separately so we can have deep aesthetic control in compositing. A holdout pass is a little harder to explain. you make a mesh (like a character) zero black and zero alpha in cases where you are rendering some other asset that is both in front and behind, like snow or smoke. The holdout permits us to render the snow or smoke separately and composite it atop the character. Probably confusing, sorry about that. Object passes simply mean if I have an environment, a horse and an airplane, I want to render them separately for later compositing control. We also do per-light passes. So if there is a sun and a sky, we will render each object twice, once for sun and once for sky, which gives us great contrast and colour control in compositing.

I am hearing that UE is going to make render farms obsolete, so that’s what I’m here to find out.


@LordOfRadiance - I haven’t experimented with it yet, but you may want to try this from the Sequencer:…***/index.html

@BrianAllenHill This is exactly what I was looking for, thank you.


@BrianAllenHill I was hoping the 2.46 preview would have this feature in the Movie Render Queue. It seemed to be mentioned in the release notes. Any idea if this is possible now? I can’t find any information on it. The main reason for my wanting to use MRQ over Sequence Recorder is the ability to render much larger print res images.

"Movie Render Queue Improvements (Beta). We’ve continued work on the new Movie Render Queue, giving you new options to control its operation and to customize the images it produces.

  • Render passes. You can now choose to export media using only selected render passes, including ObjectId, Motion Vectors, Z-Depth, World Position, World Normals, Ambient Occlusion, and Reflections. This opens up a wide range of possibilities for compositing images generated by Unreal Engine in external applications."

I’d very much like to know how the 4.26 Movie Render Queue AOVs work. Haven’t been able to find anything online other than the release notes saying it’s now implemented. In the Movie Render Queue Settings, I now see options for some Deferred Rendering options and Object Ids, but I can’t seem to find how to set up standard Render Layers to render into a MultiLayered Exr. Anyone know?

Any update on this?