i3D is now available in the App Store! But what is it? It’s a simple app that takes advantage of the Head-Coupled Perspective, or HCP, to track the face of a user in real time. The app makes your iPhone, iPad, or iPod touch’s front-facing camera lock into your face and updates the perspective of a 3D scene accordingly. The app relies solely on head-tracking; the built-in accelerometer and gyroscope are not utilized. The developers note that HCP “does not create a stereoscopic display. It provides a kind of monocular 3D display: the same picture is seen by both eyes. In the future, it might be combined with a stereoscopic display for a better 3D effect.” The app comes preloaded with several 3D scenes for you to experiment with. It’s free, so there’s no reason not to try it out. Sure, i3D is a glorified demo of sorts but hopefully such experimentation will one day lead to full-fledged games that take advantage of the 3D illusion.