 Complete the following phrase:  Ferguson relocated to New York during the late 1950s, and worked as a freelance filmmaker for the next decade. He worked on the television series Silents Please, as well as on the short film Rooftops of New York that was ultimately nominated for the Academy Award for Best Live Action Short Film. He subsequently worked with his high school friends Robert Kerr and William Shaw, along with Roman Kroitor, on the experimental 18-minute-long film Polar Life. It was shown at Expo 67 in Montreal and involved using 11 screens and projectors, with the audience situated on a central rotating turntable. The movie was received favourably, leading the four of them to establish the IMAX Corporation in 1967. They eventually replicated the initial experience, but with a single large screen and projector. This new system was launched at the 