Photo: Peter Searle

: Ash Nehru, an IEEE member, takes in the Christmas lights on London's Regent Street.

If you happened to stroll down London's tony Regent Street this past Christmas, you may have noticed, just above the festooned storefronts and package-laden shoppers, a series of clusters of glowing translucent globes. If you'd taken a closer look, you would have realized that the globes were pulsating with color, the light-emitting diodes (LEDs) within varying their hue and intensity according to the number of passersby, the wind speed, and the amount of sunlight. And if you'd looked really close, you would have discovered the quad-core Xeon computers running customized software that took inputs from people-monitoring video cameras and environmental sensors to precisely choreograph the display.

Although the promotional literature identifies the display's sponsor as cellphone maker Nokia, the actual design came from a small London-based firm called United Visual Artists, which specializes in such high-tech interactive light displays. The computer code that generated the display is the handiwork of UVA's software director, Ash Nehru.

Designing artwork that the public can interact with is immensely satisfying, Nehru says. “It's great seeing how people respond—jumping up and down, waving their arms around, walking up and then turning away. It never works quite how you think it's going to work.”

Nehru started coding as a kid, when his father, a mechanical engineer, brought home a microcomputer sold by the British Broadcasting Corp.'s Computer Literacy Project. In its day—the early to mid-1980s—the BBC Micro was an incredible machine. “It took one second to boot up and booted straight into the BASIC interpreter, so you could program immediately—in fact, that's all you could do,” Nehru fondly recalls. The computer had a faster processor than any other machine of its time—4 megahertz—and a then-remarkable 32 kilobytes of graphics memory. Best of all, he says, “it came with well-written user guides that allowed me to learn first BASIC and then 6502 assembly language programming.” Built by Acorn Computers for the BBC and sold for a few hundred pounds, it spawned legions of young programmers.

Nehru spent hours creating games and other programs. “I was 10, I had just moved to England from India, and I had few friends. But I had this computer.”

Nehru went on to earn a B.A. in computer science from Trinity College, Cambridge, in 1994. For his first job, he had just three requirements: “It had to be in London, I didn't want to wear a suit, and I wanted to work on 3‑D graphics.” He might have ended up designing avionics interfaces, but instead he got hired by computer gaming company Domark Software (later acquired by Eidos Interactive).

As a member of the research group, he looked at up-and-coming technology likely to be adopted by the gaming world. He found the work technically interesting but culturally boring. “You basically spend your days figuring out how to shoot people and chop off monsters' heads,” Nehru says.

On the side, though, he had been tinkering with generating live three-dimensional graphics—dancing robots and virtual go-go dancers—that could be displayed at music clubs and concerts. His debut “performance” came at a New Year's Eve bash at London's Alexandra Palace, where a crowd of 50 000 gyrated along with his animated characters. “People were going stark staring bonkers,” Nehru recalls. Compared to coding games, he adds, “it was a much more immediate payoff.”

Nehru quit his day job and started doing his live 3-D graphics full-time, creating dancing cartoon characters for nightclubs and pulsating light shows for raves. His work appeared throughout the United Kingdom, and he performed at the Burning Man festival a few times. He even tried his hand at being a DJ—“to no great success, of course. It was just a lot of fun.”

Fun—but not lucrative. In late 2002, right around when the money ran out, he got a phone call from Chris Bird and Matt Clark, who had also been designing visuals for live concerts. They'd been commissioned by the trip-hop band Massive Attack to produce the lighting for an upcoming concert tour. Bird, Clark, and Nehru decided to “create a show that was really of the moment and connected to the people,” Nehru says. The stage backdrop became essentially a computer terminal onto which raw data and messages constantly streamed. From a programming point of view, Nehru treated the concert like a video game, creating a timeline and scripts into which up-to-the-minute information—soccer match scores, local weather reports, e-mail messages from audience members—could be easily dropped.

That work “put us on the map,” Nehru says. Although he'd gone into the project thinking it would be a one-off, “we worked together so well, the penny sort of dropped.” Shortly after the tour ended, the three formed United Visual Artists, with the aim of creating sophisticated interactive lighting displays that blend equal amounts of art and technology.

Since then, the company has grown to a full-time staff of 13, plus a rotating crew of interns. To reach its second-floor offices in a weathered brick building in London's historic Borough neighborhood, just south of London Bridge, you can risk the semifunctional freight elevator, but it's safer and quicker to take the stairs. In the main workspace, four young designer/programmers hunch over workstations beneath a silver disco ball, while indie rock tunes waft through the air. Just beyond, in the hardware room, the guts of disassembled computers and other electronics await repair and upgrades. The place has a start‑up feel. “We all work overlong hours,” Nehru admits. “We haven't gotten to the point where we can just relax.”

Creating new works, whether for a commercial client like Nokia or for a commissioned art exhibition or performance, is a labor- and technology-intensive undertaking. A typical project starts with a visit to the site, where a team member takes photos and video, which the entire group then reviews and discusses. “About a week later, everybody comes back with their best idea. It's very important that everybody's part of the process,” Nehru says. Once the ideas have been distilled into a workable plan, “we take that to the client. Then they tell us how much money they really have,” he says, laughing.

Nehru's chief contribution is a program called D3, written in C++, that lets the designers create a detailed and realistic 3-D simulation of what the installation will look like. The program also controls the installation once it's built. On one of the workstations Nehru calls up a recent example, a music video for the U.S. rock band Battles shot in an abandoned Welsh slate mine. The team knew they'd have at most a day to shoot the video on-site, so they needed to know exactly how the lighting would work before they got there.

Onscreen, a designer has sketched the rough outlines of the mine's walls and floor and positioned the performers and their instruments within it. The set is surrounded by tall skinny poles of LEDs, which flash, pulse, and change color in sync with the music. With some simple keyboard commands and pull-down menus, Nehru can rotate the stage, change the positions of the lights, vary their color and pattern, and then see how the illumination and shadows shift.

The program isn't exactly user-friendly, but it makes the creative process more efficient and also opens up new possibilities for the designers that they can see on the fly. United Visual Artists just licensed the program to a company that rents LED equipment and control systems for exhibit halls and TV ads.

Being the guy who makes the tools that make the art suits Nehru just fine. “Writing code is just as creative as painting a picture,” he says. “You're figuring out ways to translate what's in your head into something real.”