After 33 years and 145 million albums sold, the Irish rock band U2 has an ardent fan base, but as of this summer, they can count on adding architects and engineers to that group: The centerpiece of their 360º world tour is a massive kinetic video screen-in-the-round that envelops the performers and is an integral part of the spectacle. With roughly half a million LEDs on an expandable ellipse suspended over the stage from a 90-ton steel claw, the staging makes this “by far the largest and most complex tour in history,” says Matt Davis, vice president of engineering at Hoberman Associates, the firm that developed the screen with Belgium-based Innovative Designs, U2’s show designer/director Willie Williams, and production architect and designer Mark Fisher. When it expands, “the screen provides a magic moment that is totally unique and elevates the crowd,” Davis says. ”It extends the scenery into the air and activates the space between the band and the audience.”

The screen concept was developed by Williams, Fisher, Innovative Designs’ Frederic Opsomer, and Hoberman Associates’ Chuck Hoberman. Opsomer has been a pioneer in large-format video screens, Davis explains, but the scale of this project was larger than any of them had worked on. The challenge was to create a moving screen that was truly visible from all parts of the stadiums booked for the tour, while providing high-resolution visuals for the thousands of concertgoers who, after all, are there to see the band.

The team came up with a conical ellipse with a 3-to-4 ratio and a length of 79 feet that, when closed, is 23 feet tall, and when fully expanded grows to 66 feet (approximately seven stories tall). Its framework is based on Hoberman’s expanding Iris structure, which was used for the unfolding arch at the 2002 Winter Olympics in Salt Lake City. “We know that geometry very well,” Davis says. That familiarity made it easier to create an optimized screen that could also be broken down within approximately 8 hours and packed into shipping containers. (The steel claw takes much longer to assemble, so there are three identical structures that are leapfrogging from venue to venue.) Controllable LEDs are set in 888 panels that are in turn mounted to aluminum struts on scissor-like joints. The water-sealed LEDs (FLX modules from Innovative Designs’ parent company Barco) are individually mounted in the panels, so that in case of breakage they can be easily replaced. Together, the LED panels create a 3,800-square-foot screen surface. Eight winches in the claw raise and lower the screen over the stage. Forty chain hoists, connected to pick points on the latticelike screen frame, expand and support the 120,000-pound screen.

The screen is the largest and most complex of its kind in the world, but the technology itself is not strange: “Our philosophy is to use mature technologies and standard components with known histories, but to combine them in a different way,” Davis says. “There are enough other things to invent along the way.”