built, such as the interior of a space shuttle. Van Hoytema retooled an IMAX camera to be hand-held for shooting interior scenes. Some of the film's sequences were shot with an IMAX camera installed in the nose cone of a Learjet. Nolan, who is known for keeping details of his productions secret, strove to ensure secrecy for Interstellar. Writing for The Wall Street Journal, Ben Fritz stated, "The famously secretive filmmaker has gone to extreme lengths to guard the script to ... Interstellar, just as he did with the blockbuster Dark Knight trilogy." As one security measure, Interstellar was filmed under the name Flora's Letter, Flora being one of Nolan's four children with producer Emma Thomas. The film's principal photography was scheduled to last four months. It began on , 2013, in the province of Alberta, Canada. Towns in Alberta where shooting took place included Nanton, Longview, Lethbridge, Fort Macleod, and Okotoks. In Okotoks, filming took place at the Seaman Stadium and the Olde Town Plaza. For a cornfield scene, production designer Nathan Crowley planted of corn that would be destroyed in an apocalyptic dust storm scene, intended to be similar to storms experienced during the Dust Bowl in 1930s America. Additional scenes involving the dust storm and McConaughey's character were also shot in Fort Macleod, where the giant dust clouds were created on location using large fans to blow cellulose-based synthetic dust through the air. Filming in the province lasted until , 2013, and involved hundreds of extras in addition to members, most of whom were local. Shooting also took place in Iceland, where Nolan had previously filmed scenes for Batman Begins (2005). The location was chosen to represent two extraterrestrial planets: one covered in ice, and the other in water. The crew transported mock spaceships weighing about to the country. They spent two weeks shooting there, during which a crew of about , including , worked on the film. Locations included the Svínafellsjökull glacier and the town of Klaustur. While filming a water scene in Iceland, Hathaway almost suffered hypothermia because the dry suit she was wearing had not been properly secured. After the schedule in Iceland was completed, the crew moved to Los Angeles to shoot for . Filming locations included the Westin Bonaventure Hotel and Suites, the Los Angeles Convention Center, a Sony Pictures soundstage in Culver City, and a private residence in Altadena, California. Principal