In this talk, I explore the higher dimensions of touch input. I show how to enable mobile devices to sense 3D information about the space above them from just the touch input they observe. I present a series of touchscreen devices that capture users’ fingerprints upon touch, from which they conclude 3D information. Just like camera-based 3D tracking systems provide the opportunity for more natural and expressive interaction, deriving such information from touch provides similar benefits. While camera-based systems require a certain distance between sensor and tracked objects, however, touchscreens sense information directly on their surface, which allows them to remain thin–the form factor that has allowed such devices to achieve mobility and mass-adoption in the first place. I demonstrate that reconstructing 3D information from touch enables devices to increase their input accuracy by a factor of three compared to current devices and I show that fingerprint-sensing touchscreens solve a long-standing challenge in HCI: biometric user identification. I conclude with a new model of user authentication on touch devices, demonstrate how to implement seamless biometric authentication on commodity devices, and discuss the implications of this model on existing operating systems and their user interfaces.
Christian Holz is a researcher in Human-Computer Interaction at Microsoft Research, Redmond. His research focuses on augmenting the capabilities of existing mobile devices as well as creating new devices to enrich the sensing capabilities of today’s devices. Technology Review recently named Christian one of the 10 best innovators under 35 in Germany and his work has received honorable mentions at ACM CHI and a best paper award at ACM UIST. Christian holds a Ph.D. in Human-Computer Interaction and masters and bachelor degrees in Software Engineering from University of Potsdam, Germany.