Transparent background for studio shot with backdrop

[blueman2]

I want to use a simple studio type of backdrop to create shadows and light reflection onto the subject, but I want to end up with a white or transparent background when the final render is done, creating a ping file. I don't want to have to clean up and remove the backdrop thats behind the subject if possible to make it transparent. I've tried a few things like painting the backside of the backdrop with a transparent material. I've looked for various settings in vray also but no luck. Would appreciate some help.

Sketchup17
Vray Next for sketchup

Thanks

[rspierenburg]

]I think you are looking for V-Ray Wrapper Material see this https://docs.chaosgroup.com/display/CWVRAY3MAYA/V-Ray+Wrapper+Material

See image below.

---

[blueman2]

thanks, seems like there might be something there to get me going. Found the same file for vray sketchup which is what I'm using. Will update results.