seven weeks. At one point, producers considered replacing her; however, shooting resumed on August 18, 1999, and ran until February 4, 2000. Hollow Man was one of very few films allowed to shoot directly in front of The Pentagon building, with Verhoeven expressing surprise that the script was approved, because of the themes of the United States Government commissioning scientific experiments into making living beings invisible. Many of the location scenes were shot in and around Washington, D.C., with a restaurant set also being constructed in a building overlooking the U.S. Capitol. The laboratory scenes were shot at Sony Pictures Studios in Culver City, California; the elevator shaft used in the film's climax was built onto the side of the studio's parking garage. A thermal imaging camera was employed for scenes showing "invisible" animals (most notably Isabelle the gorilla) or Sebastian following his transformation and the unsuccessful attempt to restore him to visibility; the same technique was used for characters when they look through thermal goggles. As Isabelle was played in part by a man in a gorilla suit, crew members had to stand by and warm the suit with hair dryers in order for the thermal camera to accurately emulate an actual gorilla's warmth. Despite assumptions that Bacon would not be needed on set except when his character Sebastian is visible, Verhoeven and the crew realized after test footage was shot that he would need to be present to interact with the cast, as "the other actors were stranded in empty space, and the scenes looked stiff, inorganic and unconvincing" without him. Guy Pearce and Edward Norton were also considered for the role of Sebastian before Bacon was chosen, in part for his "ability to be both charming and diabolical". At the time of Hollow Mans release, Bacon recounted a "bad morning" on which, among other mishaps, he read a story in the press that suggested Robert Downey, Jr. had been offered the film's title role. Special effects To achieve the effects of Sebastian being invisible, Bacon was digitally removed from the footage and each scene was shot twice: once with the actors and once without, for the background to be able to be seen through Sebastian's body. The crew used a motion-control camera, to ensure the same movements were achieved and the shots were then composited in post-production. For scenes where Sebastian was outlined in smoke, water and