in the rooftop segment of the chase, and digital expansion of the floor and skylight in the art gallery Bond and Mitchell fall into. The art gallery fight was intended to be simple, but during filming Craig's stunt double accidentally fell from the construction scaffolding. Forster preferred the idea of Bond hanging from ropes reaching for his gun to kill Mitchell, rather than having both men run out of the building to continue their chase as specified in the script, and the number of effects shots increased. To film the aerial dogfight, a "Snakehead" camera was built and placed on the nose and tail of a Piper Aerostar 700. SolidWorks, who provided the software used to design the camera, stated "pilots for the first time can fly as aggressively as they dare without sacrificing the drama of the shot." The camera could turn 360 degrees and was shaped like a periscope. The crew also mounted SpaceCams on helicopters, and placed cameras with 1600mm lenses underground, to cover the action. Forster wanted to film the plane fight as a homage to Alfred Hitchcock's North by Northwest, and chose planes like the Douglas DC-3 to suit that. The free-fall scene involved its own set of challenges; director Marc Forster didn't want to shoot the scene against a green screen. The scene was shot in an air tunnel at Bodyflight, which offers the same effects as skydiving. Daniel Craig and Olga Kurylenko did their own stunts for this scene. While a great solution for the actors' performances, the technique presented enormous VFX challenges: relighting shots captured in a tall white tube to match the sky over the Bolivian desert; and the impossibility of filming medium to wide shots of the actors. An array of eight Dalsa Origin cameras (supported by seven HD cameras and a 35mm hand-held camera, all running in sync) was used to create a virtual camera with which to shoot the actors floating in the simulator. Ged Wright and his team at Double Negative developed a method to use the data from these cameras that allowed these real performances to be placed in a synthetic environment as seen by a synthetic camera. During the shooting in the wind tunnel Craig and Kurylenko wore wind-resistant contact lenses that enabled them to open their eyes as they fell. For safety and comfort, they only shot for 30 seconds at a time. Forster