In which Disney animated film did CGI first appear?

The Great Mouse Detective was the first Disney animated film to extensively use CGI. Its most notable computer-generated work appears in the film’s two-minute climax inside Big Ben.

For that sequence, animators Phil Nibbelink and Tad Gielow designed the clock tower’s gears as computer-generated wire-frame graphics. The imagery was printed, traced onto animation cels, and combined with traditionally drawn characters and backgrounds. This hybrid process made the machinery appear too complex and repetitive to animate efficiently by hand.

Released in 1986, the film was based on Eve Titus’s Basil of Baker Street books and followed a mouse detective modeled on Sherlock Holmes. The computer-assisted Big Ben sequence became an important technical milestone and helped Disney demonstrate that computer animation could support hand-drawn feature films.

The wording can cause confusion because later films achieved different milestones. The Little Mermaid first used Disney’s CAPS digital ink-and-paint system in a limited sequence, while The Rescuers Down Under became the first feature-length film produced entirely through that digital system. Those are different achievements from Disney’s first extensive use of CGI.