Virtual space inside and out

By Greg Freiherr, Editor, gfreiherr@cmp.com

It's been a decade since I visited NASA's Jet Propulsion Laboratory, but I'll never forget what I saw. There, in JPL's advanced visualization facility, digital imaging opened a gateway into deep space. This transom, constructed with radar data obtained from a space probe circling Venus, took me to the inhospitable but eerily beautiful planet. I flew through valleys and up the slope of a volcano, circled its peak and turned to cross vast fields of hardened lava. It was hard to imagine a place I would less like to be, but virtual CT and MR fly-throughs have supplied that location.

The imaging community has seen a steady stream of software that can visualize the insides of body cavities. The clinical value of some of this work has yet to be proven, but the potential is extraordinary. People are visually oriented. Our brains process information on the basis of past experience. That's why virtual colonoscopy is so intriguing. It delivers information in exactly the way diagnosticians are trained to interpret it, without the bother or patient discomfort that would otherwise be necessary.

As I near the age when colon cancer screening should become a periodic part of my preventive maintenance, I am especially impressed by the progress made in this area. And whenever I look at the images rendered by the medical software packages, my mind wanders back to JPL. The radar mapping of Venus took months to complete. The data took years to reconstruct. Each point on the planet's surface was meticulously plotted in 3D to create a topographical map, the first such map of Venus ever constructed. Designing the virtual fly-around of selected places took only a couple weeks. But it was in these 3D virtual reconstructions that the shortcomings of space exploration and the power of people were most apparent.

Every so often, it turned out, a bit of data had gotten lost somewhere between Venus and the earth. A pixel here. A pixel there. It all added up to tiny holes in the 3D voyage above the planet's surface. In a darkened lab, at a workstation tied to a multimillion dollar computing system, one particularly talented technician filled in the missing pieces. She likened the work to that of an artist restoring fragments of a masterpiece lost over the centuries.

In inner space, as in outer space, there is still an art to the interpretive process. It's being made more precise by technology that was hard to imagine just a decade ago. But it is worthy of special note that techniques first used to explore a planet are having an impact so close to home.