06/23/97 UNC: TOOLS TO MANIPULATE VIRTUAL WORLDS

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UNC: TOOLS TO MANIPULATE VIRTUAL WORLDS
North Carolina's devices help visualize molecules or guide a surgeon's hand
Floating before my eyes is a slice of an almost unimaginably tiny world. It looks like a pair of long, low hills rising from a featureless plain. But those ridges are actually ''buckytubes,'' soda-straw-like molecules thousands of times thinner than a human hair. And I can do more than just look. Thanks to an atomic force microscope, powerful computer-graphics equipment, and precision motors connected to a small joystick, I can ''feel'' every bump and dip as I guide a little red ball across the simulated landscape. I can even push the buckytubes around.
When University of North Carolina computer scientist Russell M. Taylor first began developing this virtual reality ''nanomanipulator'' system, his physics department colleagues figured the new, more precise way to control the microscope would be a boon--but they weren't sure fancy real-time computer graphics were that important. Now, they're believers. ''We wouldn't have been able to do the experiments we've done without it,'' says UNC physicist Richard Superfine. He and co-workers have used the tool to probe the properties of buckytubes--and discover precisely how the surfaces ripple when the tubes are bent.
The value of Taylor's 3-D window into the Lilliputian world of molecules also epitomizes the credo of UNC's vaunted Chapel Hill computer-science lab: Build visualization tools that are actually useful to someone else. ''It's too easy to fool yourself that you're making progress if you work just on your own problem,'' explains professor Frederick P. Brooks.
That's why researchers Andrei State and Mark A. Livingston are working with doctors on an ''augmented reality'' system for doing biopsies of tissues such as breast or liver. Wearing a head-mounted display equipped with video cameras and linked to an ultrasound probe, a surgeon can ''see'' down inside the breast to a suspicious lump, making it easier to insert the biopsy needle in the precise location. ''It's like Superman's X-ray vision,'' explains Livingston.
Other projects allow chemists to probe the interactions of virtual molecules, or enable engineers to ''walk through'' the engine room of a submarine. But they also put UNC computer scientists on the cutting edge of science and technology. Since the late 1980s, the lab has designed or built a series of world-beating graphics computers that construct realistic-looking images from millions of basic triangle shapes. Each chip board on the most recent machine, dubbed PixelFlow and licensed to Hewlett-Packard Co., can process up to 2 million triangles per second--and dozens of boards can be strung together to make what may be the world's fastest graphics machine.
EXOTIC LOCALES. Powerful computers that generate realistic-looking scenes in real time, however, are only a part of the puzzle. In the dream of UNC's dynamic Henry Fuchs, computer technology will allow people to be ''present'' in a scene. High-resolution displays mounted in eyeglasses--not today's cumbersome headgear--could take people to exotic locales or offer crucial information to augment the real world. Soldiers' eyeglasses, for instance, could pinpoint mines or snipers, while surgeons could see deep into the body.
But this will only work if the system is capable of tracking the exact position of the person wearing the displays. Otherwise, the simulated world won't match up with the real one and ''the perception of reality breaks down,'' Fuchs explains. So UNC researchers are hard at work on better tracking systems. One clever approach, pioneered by professor Gary Bishop, uses light-emitting diodes mounted in the ceiling that work like stars in a celestial navigation system. Another, still hush-hush until patent applications are filed, would employ imperceptibly flashing lights to help a computer calculate the position of the person illuminated by the flashes.
Fuchs can't predict whether virtual reality will be a revolution or a bust. ''It's not clear if we can do it--or if it's worth doing it,'' he admits. But UNC's computer lab, he says, is betting that it will be. Says Fuchs: ''We are trying to make 3-D dreams come true.''
By John Carey in Chapel Hill, N.C.

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