which race cars were later digitally added. Tanner Foust took on the role of driving Stark's racing car. Also in June, it was reported that John Slattery had joined the film's cast as Howard Stark. Olivia Munn was also cast, in an unspecified role. A massive green screen was constructed at the Sepulveda Dam to film a portion of the Stark Expo exterior, with the rest either shot at an area high school or added digitally. To construct the green screen, hundreds of shipping containers were stacked, covered in plywood and plaster, and then painted green. For the conclusion of that climactic scene, which the crew dubbed the "Japanese Garden" scene, a set was built inside Sony Studios in Los Angeles. Filming lasted 71 days, and the film's production officially wrapped on July 18, 2009. A post-credits scene depicting the discovery of a large hammer was filmed on the set of Thor, and some of it was reused in the film. Jon Favreau revealed that the scene was filmed with anamorphic lenses to match Thor, and was directed by Kenneth Branagh, the director of Thor. Post-production In January 2010, IMAX Corporation, Marvel, and Paramount announced that the film would receive a limited release on digital IMAX screens. It was not shot with IMAX cameras, so it was converted into the format using the IMAX DMR technology. The film underwent reshoots in February. Olivia Munn's original role was cut, but she was given a new role during the reshoots. Janek Sirrs was the film's visual effects supervisor, and Industrial Light & Magic did the majority of the effects, as it did on the first film. ILM's visual effects supervisor on the film, Ben Snow, said their work on the film was "harder" than their work on the first, stating that Favreau asked more of them this time around. Snow described the process of digitally creating the suits: ILM created 527 shots for the film, using programs such as Maya. Perception worked on over 125 shots for the film. They crafted gadgets, such as Tony Stark's transparent LG smartphone, and created the backdrops for the Stark Expo as well as the computer screen interfaces on the touch-screen coffee table and the holographic lab environment. In total, 11 visual effect studios worked on the film. Music A soundtrack album featuring AC/DC was released by Columbia Records on April 19, 2010, in at least