Before Crichton's book was published, four studios put in bids to acquire the film rights. Spielberg, with the backing of Universal Studios, acquired the rights for $1.5 million before publication in 1990, and Crichton was hired for an additional $500,000 to adapt the novel for the screen. David Koepp wrote the final draft, which left out much of the novel's exposition and violence and made numerous changes to the characters. Filming took place in California and Hawaii between August and November 1992, and post-production rolled until May 1993, being supervised by Spielberg in Poland as he filmed Schindler's List. The dinosaurs were created through groundbreaking computer-generated imagery by Industrial Light & Magicin conjunction with life-sized animatronic dinosaurs built by Stan Winston's team. To showcase the film's sound design, which included a mixture of various animal noises for the dinosaur roars, Spielberg invested in the creation of DTS, a company specializing in digital surround sound formats.