T-Rex: Back to the Cretaceous is a 1998 edu-tainment feature filmed for the IMAX 3D format. The film is directed by Brett Leonard, renowned for his Computer-generated imagery special effects productions. Executive producer/co-writer Andrew Gellis and producers Antoine Compin and Charis Horton also make up the production team. Actors Liz Stauber and Peter Horton star, alongside Kari Coleman, Tuck Milligan and Laurie Murdoch. The film is among the few IMAX films that are considered "pure entertainment" though it still is considered rather educational by the mainstream audience.
The plot revolves around 16-year-old Ally Hayden (Stauber), the daughter of a world-famous paleontologist and museum curator (Horton). She loves dinosaurs and longs to be able to accompany him to one of the nearby paleontological digs, but her father thinks this is too dangerous and she has to settle for giving museum tours instead.
A mysterious accident at the lab revolving an oblong fossil rock happens while Ally's father is away at a dig site with his assistant (Coleman), and Ally is magically transported back in time. Among the various time periods she visits are the Cretaceous, when the Tyrannosaurus rex and Pteranodon existed.
Ally is also transported to the early 20th Century where she meets renowned historical figures in the world of paleontology. These include dinosaur painter Charles R. Knight (Milligan) and paleontologist Barnum Brown (Murdoch), arguably one of the most famous paleotogists in early fossil-hunting history.
Principal photography began on September 22, 1997, on location at Dinosaur Provincial Park in the Badlands region of Alberta, Canada, and near the town of Brooks. Filming began by capturing the scenes in which Ally Hayden time-travels back to the turn of the century to go on expedition with famous bone-hunter Barnum Brown.
Filming continued for two weeks on location in Dinosaur Provincial Park. Yet the filmmakers faced a challenge in finding a realistic environment to set the live-action filming portion for the Cretaceous period sequences when Ally finds herself wandering amidst the lush vegetation of 65 million years ago. The location used to film Cretaceous period scenes in the end was in the Olympia rain forest in upper Washington state.
The special considerations that must be made when working with IMAX 3D presentation also made it crucial that the background features of the shooting locations were ideal.
Besides shooting locations, extensive computer-generated imagery was also employed to ensure the realism of the dinosaurs depicted in the film. Models had to be sculpted and digitized, with details such as texturing crucial to the process. The filmmakers of the next year's television documentary series Walking with Dinosaurs also faced similar challenges.