CRISTAL consists of an interactive multi-touch surface and a camera, mounted in the ceiling of the living room capturing the entire living room. The interactive surface is integrated into the coffee table and extends its functionality. The display itself is only activated on demand and still can be used as a normal coffee table. When activated, the interactive surface shows the live camera feed. To control the devices in the living room, users can directly manipulate them by touching the corresponding video image. Depending on the controlled device different types of input are possible. A sliding gesture over a floor lamp, for example, modifies the brightness of light source.
On the other hand, a similar gesture across the floor in front of a robotic vacuum cleaner defines a path for it to follow. To watch a movie, a user can select a movie from a digital movie collection invoked directly on the table surface and drag it onto the TV in the video image. The live video image displayed on the table gives continuous real-time feedback to the user.