Is there a method for creating a matte material on an object which effectively doesn’t render anything behind it?

It’s for an object in an AR experience, so the backgroundImage needs to remain unaffected. Normally this would be used for an invisible groundplane or similar so that things can be masked off

Cheers in advance

I´m interested in the very same problem. Does really nobody out there know any kind of approach? I can accomplish it using flare3D but would rather stick to Away3D cause that´s the framework I know best (by far).

thanks in advance
best wishes
MMeX