What was planned as a documentary became something else: the world's first 3D art house film and Wenders' true testimonial to the woman many credit with revolutionizing the art of dance.The film, which will screen out of competition in Berlin, is the culmination of an obssession with Pina's work that Wenders says began the moment he saw Bausch's Tanztheater in 1984."I saw the first piece of Pina's and immediately saw five more -- I saw everything she did," he says. "I'd seen some classical dance, but I was always bored. Here was something completely different. Even calling it modern dance is inappropriate. She created the word tanztheater, dance theater. What she does is plays where the acting is done by dancers."Bausch's work is, on the surface, worlds away from the films of the German auteur. Although her pieces often contain snatches of dialogue -- itself scandalous for classical-dance purists -- there is no discernable narrative. Wenders had done documentaries, but the subject -- in Buena Vista Social Club and The Soul of Man -- was always music. In his huge body of work, there are no overt references to dance.But from the moment he saw it, Wenders knew Bausch's Tanztheater belonged on the big screen. The only problem was, the director of Paris, Texas and Wings of Desire had no idea how to do it."It became a running joke," Wenders says. "She'd say, 'Wim, when are you doing that movie on me?' and I'd say, 'Pina, I don't know how.' "The problem was space. Imagine shooting a dance performance: Where do you put the camera? Do a close-up of a single dancer, and you miss what's going on behind, in front of and beside them. Pull back for a wide shot, and the scene flattens out; you can see everyone, but the emotion is gone. And Pina's dances are emotional to the core."The more I got to know her work, the less I thought I was able to shoot it in a way that was valid," Wenders says.Then, in 2006, he saw an early cut of the groundbreaking digital concert film U2 3D in Cannes."It was the first 3D film, the first to use this new technology," Wenders says. "I called Pina from the screening. I said, 'Now I know how.' "