Turntable Render, with opacity but alpha/chroma background?

Hi there,

I use UE4 for cinematics and VFX. My current project requires a shot of a rotating burning building, which I am aiming to deliver with a transparant background; this will then be comped by the client into a scene he has already shot.

Is there a way I can add a postprocess volume/material and get a cinematic camera to render only what is inside this volume? Alternatively is there a material that can be applied to the camera to render only a ranged sitance from camera?

My model has some small areas of transparant material, and will have emmisives (fire) and ideally semi-opaque smoke- all of which present problems for a chromakey solution.

Any advice would be greatly appreciated.

thanks,

Alex