[Zenst]

Tracking speakers is best done via audio already linked to camera control. Now face tracking by camera's in VC was something I first encountered late 90's - can't recall kit, but Sony was first on that - which was good for presentations in which the person speaking was standing and moving.

As for perspective shifting based upon multiple inputs - processing wise look at raytracing as would need to map each camera input to extrapolate the suface details and then map that out to the virtual visulisation. Basicly you would need to 3D map, including textures and re-render that viewpoint required.

However, do you need the whole face - you just really need to fix the eye's IMHO and eyeline contact.

But that is down to how we interact in meetings with people - try doing a video conference in which everybody is wearing dark sunglasses - that is insightful as you find people focus more upon what they hear more then.