Panoramic Capture with alpha for compositing


I was wondering if anyone has been able to export panoramic captures (using the Panoramic Capture tool) with transparency. I’m trying to render a scene so it can be composited on existing 360 video. So far I’ve been only able to do this by using a green screen sphere around the scene. I can see there’s a SP.ForceAlpha setting which I’m guessing implies it should be possible but regardless of what I set that to I always get frames with black background instead of transparent (I’m assuming that an empty background in the scene should render as transparent?). Any help will be appreciated.

you can try rendering with custom stencils on as a separate render for alpha