Rendering PostProcessing Materials through Matinee

Hey guys!

I’m looking to use Unreal for film.
Take for example a spaceship landing on a background plate.

What we’d usually do in Cinema4D is render the spaceship & particles.
Then, render the shadows separately without the floor, so it can be composited in After Effects.
Also, sometimes we use Object Buffers, which means we render a black/white image of all the objects in the scene, effectively cutting out shadows for layering in AE.

I want to do this in Unreal, however, the Matinee export doesn’t have a transparency option (PNG?).
Therefore my question is:
Is it possible to set postprocessing materials to “only” render shadows? Or, to only render specified objects (similar to object buffer), so they can be layered in After Effects.

I find a few questions surrounding this on AnswerHub, but no answers. Does anyone know?

-TT

Nobody? (Sits in a corner and sobs)