Rock groups don’t get any bigger than U2, which brings along a thunderously entertaining stage show wherever it goes. Stereoscopic 3D production company 3ality Digital Entertainment traveled with the Dublin lads to several concert dates in Mexico and South America. What was the big idea? To make a 3D concert movie as intense and explosive as the band’s performance.

Related story: read about post on U23D.

When U23D debuts this week at the Sundance Film Festival, audiences are likely to have the same reaction as preview audiences in Los Angeles and New York: simply put, U23D breaks new ground in 3D stereo filmmaking. It’s as immersive an experience as the concert – without the perils of crushing crowds.

From the production point of view, U23D marks several firsts in 3D filmmaking. According to 3ality officials, it’s the first stereo film that uses zoom lenses, the first to create three- and four-layer composites, and the first to incorporate fast cuts that don’t result in a headache or nausea.

All this has been done via proprietary hardware and software developed by 3ality Digital Systems in its R&D facilities in Burbank and Mà¼nich (manufacturing is done in Germany). “The work we’ve done has opened up 3D filmmaking to any director,” says 3ality President Sandy Climan. “Our intent is to make the tools so intuitive to create the Z axis of storytelling that the camera and post tools become a seamless partner for filmmakers.”

What Climan and 3D/digital image producer Steve Schklair hope is that, if 3D tools are made more seamless and intuitive, more filmmakers will explore the possibilities of 3D films. “With U23D, what makes the most impact are not the special effects of 3D but the emotion that 3D creates,” says Climan. “The intent in the film is that the 3D elements are sculpted as part of the composition of each song. They’re there to immerse you, not distract you. Our goal is to champion 3D as an art form.”

Produced by 3ality Digital Entertainment, U23D relied on camera rigs built by its Digital Systems division that overcame many obstacles faced by 3D productions. Schklair notes that rigs used to hold two cameras eye distance apart have always been problematic. They were heavy – weighing 200 to 300 pounds – and, because they were one-offs just welded together, they wouldn’t fit onto standardized cranes, rigs, or mounts. Every time operators changed film mags or lenses, the two cameras had to be re-aligned. All this meant that the typical 3D production was only able to go through three to four set-ups a day, says Schklair.

“The impetus [to build our own system] was, how can we shoot stereo and do 20 to 30 set-ups a day?” he says. “Digital solved that. We didn’t have to change film mags. And if we could fit the cameras with a zoom lens, we wouldn’t have to change lenses.” He credits the Zeiss DigiZoom lens as being the solution. “It’s as sharp as the primes, so there’s no trade-off,” he says.

But using zoom lenses was not a panacea for production. Although the U2 production pre-dated this development, 3ality Digital Systems has since built a proprietary software method that compensates for telecentricity – the fact that the each zoom lens will veer around the optical center in its own way as it zooms in. “Telecentricity is consistent within each lens, so the system builds a LUT that will move the camera during a zoom to compensate for it,” he says. “Otherwise, the lens will move 20 to 30 pixels, but twice that is 60 pixels, which is a problem. Our software gets them to be accurate within one to two pixels.

Although U23D didn’t have the benefit of that software, says Schklair, the nature of the production – a single set-up a day – allowed them to avoid much of the problems. To prepare, they brought two of their TS-1 stereo camera rigs, mounted with Sony F950 HD cameras, to Mexico for a practice run. “We shot with the rigs in Mexico City to get used to the rigors of shooting in real time, using the cameras and getting used to U2’s staging,” says Schklair. “It was a get-warmed-up shoot.” Learning U2’s choreography for the concert enabled directors Catherine Owens and Mark Pellington to know exactly where to put the camera rigs. It also allowed the 3D team to zero in on their choreography. “The two settings we worry about are the settings we use for 3D: interocular and convergence,” says Schklair. “The rehearsal shows helped us learn the range of settings and got us more familiar with the show.”

After the Mexico warm-up, the 3ality team sent one camera to Chile and the second to Brazil to continue shooting U2 concerts … and to prepare for the big finale in Buenos Aires, Argentina. In Buenos Aires, they collected 18 HD cameras (most of them F950s) for the nine TS-1 stereo rigs. U2 would play two concerts there, in sweltering heat, to a crowd of 90,000 fans. “It was 18 Sony 950s, 18 Sony HDCAM-SR recorders, 18 CCUs to control and monitors for everything everywhere,” says Schklair. “The fiber optic was running everywhere.”

There were, of course, some unexpected challenges. “Every country in South America had a different electrical standard,” he says. “U2 said we could use their lighting power, but it didn’t work out. So we’d find generators at each stadium, and have these massive generators behind the stadium that we had to run to camera positions and engineering stations. That was our biggest gotcha.”

The trick was to place the camera rigs so that they wouldn’t capture other cameras or block the audience’s view. “But we wanted close-ups with a wide lens,” he says. “So the night before the concert, U2 did 10 songs just for the camera crew – full performances. And that’s where we got all the close-ups.” To avoid capturing other camera rigs, the team would shoot one night right to left, and the second left to right. In other places, they shot from the back of the stage.

The team had two Technocranes, two jib arms and a Spidercam, which moves the camera in sweeping motions through space. According to Schklair, the production shot in 4:4:4 because of the great latitude in the concert lighting. “There was a 20K spot on Bono and 10 feet away was complete darkness,” he says.

Making the shoot even more challenging, 3ality had two days to set up. “On the big days, we had up to 140 crew members, mostly porters to get the gear onto the stage quickly. We learned how to do it from the U2 crew, which had 200 people in color-coded T-shirts, each team responsible for a task. We patterned what we did after this.”

The camera equipment held up beautifully, says Schklair, except for a sole camera. The massive crowds were so hot that security would hose them down from nearby barrels of water. One camera was inadvertently drenched. After that, the team waterproofed all the cameras.

“The key to being able to do this was designing systems that were able to shoot 3D on the fly, motorized and repeatable with incredible precision, ” he says. “It only takes a few microns to be off a few pixels.”

Related story: read about post on U23D.