Chinese star Andy Lau became involved in negotiations to join the film, as a Chinese scientist and old friend of Stark's who comes to his aid. Lau would later turn down the role, and Wang Xueqi was cast instead. Jessica Chastain entered into discussions for a role in the film, but bowed out due to scheduling conflicts. In May, Rebecca Hall was cast in her place, and her role was described as "a scientist who plays a pivotal role in the creation of a nanotechnology, known as Extremis." Over the next few weeks, James Badge Dale was cast as Eric Savin, Ashley Hamilton was cast as Firepower, and Favreau returned to reprise his role as Happy Hogan from the first two films. Stéphanie Szostak and William Sadler were also cast in the film, with Sadler playing the President of the United States. Despite erroneous early reports that Cobie Smulders would reprise her role as Maria Hill from "The Avengers" in the film, Smulders wrote on her verified Twitter page that this was not so. According to Drew Pearce, Emilia Clarke was initially cast for an unknown role, before the script was changed. Filming began in Wilmington, North Carolina on May 23, 2012 at EUE/Screen Gems Studios, with the working title "Caged Heat". Cinematographer John Toll opted to for the first time in his career work with digital cameras, as he found them more convenient for a visual effects-heavy production. Toll shot the film primarily on the Arri Alexa camera. From June 4 through June 6, 2012, filming took place in Cary, North Carolina at the Epic Games headquarters and SAS Institute, with a large Christmas tree set up on the front lawn. A scene was also shot at the Wilmington International Airport. The Port of Wilmington served as a location for the oil tanker in the climactic battle, along with a soundstage recreation of the dock. The crumbling house itself was filmed in a hydraulic-powered giubo platform that could bend and split into two pieces. All the interior footage had practical effects, including debris and explosions, with computer graphics used only to add exteriors and Iron Man's armor. From July 19 to August 1, 2012, filming took place on Oak Island, North Carolina, to "film aerial drops over the Atlantic Ocean." They were done for the scene where Iron Man rescues the people falling from the Air Force One over Miami, which were originally envisioned done with green screen effects, but were changed to using actual skydivers as second unit director Brian Smrz knew the Red Bull skydiving team.