[1] - Original work: "Using the Userʼs Point of View for Interaction on Mobile Devices" In Actes de la 23ème Conférence francophone sur l’Interaction Homme-Machine (IHM’2011, Nice, Octobre2011).
[2] - Other possible solutions: http://www.vision.ee.ethz.ch/~gfanelli/
[3] - iphone demo: http://youtu.be/2pRamDMOUkk
[4] - 3D Head Tracking Webcam OpenCV http://youtu.be/h9kPI7_vhAU