Compositing UE4 Output (movies with alpha?)

It’s official!

I’ve used UE4 to replace my offline rendering! I just completed my first job with it and my client couldn’t tell the difference- they were just blown away by how quickly I got it out and “rendered” changes!

That said, I’ve got a few things I can’t figure out. I think one is doable, but coming from an offline rendering background, I’m not sure how to do it. The others might just be “wishlist” items. Either way, very happy with UE4!

Here’s my list:

  1. Is there some way to make a “matte/shadow” material? Something that will catch shadows/reflections but only show those? The idea being that I then composite the UE4 sequence over something else in Nuke or AE.

  2. Can import geometry with animated vertices? (Like an alembic or vertex animated fbx files?)

  3. Can I import animated maps/sequences? I’m familiar with having a series of images in a single sheet and then telling UE that it’s a grid and to cycle through… but for what I do that would create a HUGE file! Being able to import an AVI, MP4, or something like that would be great!

1–I don’t think that’s possible with how it’s setup, if the object is transparent then the light will go through it
2–not yet, there’s not any plans currently for that feature but I wouldn’t be surprised to see it at some point. Currently you can export skinned animation along with standard rigid/non skinned animation
3–movie texture support is coming, there’s someone that’s been working on a plugin for it and Epic is working on their own implementation.


1- Dang! Oh well, I’m sure I can fake it in AE for now.

2 - I used the FBX import process to drive both rigid and skinned animation out of Max for the recent project- worked great! For 80% of the work I do, that should be just fine. However, it would be really nice to have some of the thinkingParticles work rendered in UE4. I can bake it down to FBX but to really get some of the intended effect I need to be able to import geometry with dynamic vert counts. Same goes for some of my RealFlow work. I’ve used CryEngine’s geomcache and it works really well but the rest of the toolkit just doesn’t do what I need (at least at my novice level- it is pretty cool though).

3 - Shortly after submitting I came across the thread about using the Windows Media function to get movies as textures- I’ll try it out!

For your first issue - couldn’t you just render out a “pass” with all the lighting settings turned on and a white diffuse shader applied globally. This would give you the equivalent (at least if my current vRay/Nuke pipeline holds) of a raw lighting pass which you can then multiply over your diffuse pass - or use as a luma mask for other corrections. Likewise if you have hold out passes you could solo the object you want in this “raw lighting pass” and invert the shadows to create a pretty solid “faux” matte pass. I can throw together a quick example graph in Nuke later if you’d like! :smiley:

That, good sir, is what I was thinking! I got a reply on the other forum that laid out some pretty nice options for getting render passes out of UE4: View Modes | Unreal Engine Documentation

Thanks for the reply!

Great find - definitely bookmarking!

also just to add to the discussion if you apply a blendable to the GlobalPostProcess and then create a new material that’s a post process, in the emissive channel assign a sceneTexture node to it and in the that node, choose what layer you want in the properties, then when you render out of the matinee it respects that in the renders.
so you can output reflections and diffuse etc.

I’ve had some success with using morph targets to animate vertices in geometry. I usually set up the morph targets in Blender then set up a blueprint to animate the morph value.