Nintendo files 3D tracking device patent

[TomaTito]

The Amazon Fire does that on a mobile phone for 199. It uses two stereo cameras (but has four for robustness)

http://techcrunch.com/gallery/heres-what-the-amazon-fire-phones-crazy-3d-head-tracking-looks-like/

http://techcrunch.com/2014/06/18/amazon-announces-the-fire-phone/

http://techcrunch.com/2014/06/18/here-is-the-full-video-of-amazons-fire-phone-launch-event/