Interactions with computers have expanded into the physical world. Recent developments of low-cost gesture-tracking technologies, like the Microsoft Kinect, have enabled millions of users to interact with their computers by gesturing with their bodies. Furthermore, computer-vision tracking and registration techniques now enable novel projection-based displays to overlay projected images into our physical environments, creating entirely new augmented-reality experiences. These natural interfaces will continue to be incorporated into mobile devices, where they will enable rich interactive experiences anywhere, anytime.