The Human Body as a User Interface

Summary form only given. "The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it." Seldom has an era begun equally decidedly as the age of Pervasive Computing with these famous words from Mark Weiser has in 1991. However, while computers have almost shrunk to disappearance in the meantime, user interfaces have not. The challenge of the "natural user interface" has obstinately resisted all efforts of improvement and, for example, voice recognition is still in its infancy. Amazingly, the potential of motion tracking has not been exploited beyond very narrow confines either. This is a pity because the performance of sensor hardware has lately made remarkable progress. At the example of selected projects including a Virtual Panorama, an Electronic Score, a Tai Chi motion trainer and a biofeedback system for Buto dancers that have emerged from our systems research, we shall illustrate how the human body itself can serve as a seamless and powerful user interface for innovative computer applications. We shall explain and discuss some tracking and classifying algorithms and, at the examples of Tai Chi, Buto and a medical monitor of heart activity, elaborate on the subtle transition from using body movement to control a computer to using a computer for analyzing body movement and state.