FX. Townsend said that from January 2013 through the end of filming in April, the collective crew had one day of downtime, otherwise working seven days a week and 14 to 18 hours a day. Digital Domain, Scanline VFX and Trixter each worked on separate shots featuring the Mark 42 armor, working with different digital models. The studios shared some of their files to ensure consistency between the shots. For the Mark 42 and Iron Patriot armors, Legacy Effects constructed partial suits that were worn on set. Townsend explained that "Invariably we'd shoot a soft-suit with Robert then we'd also put tracking markers on his trousers. He would also wear lifts in his shoes or be up in a box so he'd be the correct height—Iron Man is 6'5". During shooting we used multiple witness cams, Canon C300s, and we had two or three running whenever there was an Iron Man or Extremis character." The artists studied time lapse photography of decaying fruit and vegetables and actual phenomena such as the aurora borealis as reference for the effect of the glowing Extremis characters. The heads-up display features of the helmet were inspired by visualization techniques from MRI diagnostic pattern recognition and graph theory, particularly by the connectogram, a circular graph that maps all of the white-matter connections of the human brain. The film's production was delayed following Downey's leg injury, and for certain shots they were forced to create a double for Downey. Townsend explained that "The collective VFX [supervisors] and unit leads ran into a room as soon as the incident happened to try to ascertain what sequences could they shoot." Certain shots were filmed with a body double on set, and Weta Digital created a digital body double for others. A total of three hours and 15 minutes of footage were shot before editing, where it was brought down to 130 minutes (119 without the credits), marking the longest stand-alone Iron Man film. Post-production also had a 3D conversion and a digital remaster for the IMAX release. Todd-AO mixed the sound in Dolby Atmos to enhance the immersive experience. Trevor Slattery was originally meant to die in the film, appearing during the climatic oil rig battle with an Extremis injector and promptly blowing up after taking it. Pearce said that was "the most Monty Python of all of the beats" in the film. During the editing process, it