LucidTouch is particularly useful in two situations, Baudisch says: when multitouch interaction is desired, and when a touch screen is very small, perhaps as small as a watch face. He declined to say when or if LucidTouch might become a product, saying researchers would continue to perfect it while looking for applications such as mobile gaming, art and spreadsheets.

Asked about an extension of LucidTouch from touch to gesture recognition, Baudisch says the Microsoft prototypes already can act on finger gestures, with the system recognizing finger motions as well as positions and understanding the meaning of different numbers of fingers. For example, the motion of one finger is seen as equivalent to a mouse movement, a finger touch is interpreted as a click, and two fingers touching and moving is seen as a scroll command.

Touch technology in its many variations is an idea whose time has come, Baudisch says. "It's been around a long time, but traditionally in niche markets. The technology was more expensive, and there were ergonomic problems," he says. "But it's all kind of coming together right now."

The rise of mobile devices is a big catalyst, he says, with the devices getting smaller and their screens bigger. When a screen covers the entire device, there is no room for conventional buttons, he points out. And that will give impetus to other types of interaction, such as voice, he says.

Touch on a grander scale

But not all the advances in touch technology are going into tiny mobile screens. Microsoft's Surface computer uses a two-way touch screen that is 30 inches across, big enough for several people to sit around and use simultaneously. It is intended to lie flat and present a 360-degree user interface.

Cameras embedded inside Surface sense user input in the form of touch and gestures (finger movements across the screen) and can capture the information needed to identify objects laid on it. This information is shipped to a garden-variety Windows Vista PC for processing and the results returned to Surface by a Digital Light Processing projector. It is a vision-based system, not capacitive or resistive as are many conventional touch devices.

The art of touch

Ico Bukvic, a professor of music technology at Virginia Tech in Blacksburg, has taken touch to an extraordinary level, using the Lemur multitouch "control surface" from the French company JazzMutant to compose and perform musical works on the fly, allowing a user to move his hands and fingers to "conduct" the music coming from a computer.

Bukvic works with "interactive multimedia art," which can combine animation, video, recorded and on-the-fly electronic music, and other things in ways that enable the artist, the audience and the computer to work together in a "symbiotic circle," he says. The user can make an artistic presentation by controlling dozens of parameters -- video brightness, virtual camera position, sound pitch and amplitude, mix of instruments and so on -- with all 10 fingers, much as a pianist plays a complex piece while improvising on it.