The opening act of Indiana Jones and the Dial of Destiny takes place a quarter-century prior to the rest of the film. That required the filmmakers to de-age Harrison Ford to (mostly) good results. More details have come out about the behind-the-scenes process and why it took three years to complete.

In an interview with Variety, artists from Industrial Light and Magic — the VFX company that spent three years working on the film — spoke about the latest Indiana Jones movie. One of the VFX supervisors said, “We knew we would have to use all of the tools we already had and develop some new ones.”

They created the ILM FaceSwap, a technology that allowed them to create a fully CG 3D head that they could then combine with on-set photography. The team based Ford's younger face on “machine learning-based reference material from previous Indiana Jones films.”

Granted, they still needed Ford in the flesh for some parts of it. VFX supervisor Robert Weaver explained, “That involved putting Harrison through the process of recording all the facial performances and all its extremes, and the marrying of various technologies by the artists to blend between one and the other to get the final performance that you’re looking for.”

He continued, “The important aspect is that there’s not a single recipe that was cooked up that could be done for all shots.”

ILM is no newbie to the de-aging game. Outside of their work on the latest Indiana Jones, the company also did similar work for Ant-Man and the Wasp: Quantumania and The Irishman. Martin Scorsese's The Irishman remains the standard for Hollywood when it comes to de-aging — mostly because it wasn't too jarring (especially in the case of Al Pacino in Joe Pesci) and the film never asked its actors to push their physical limits outside of one awful deli scene.

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Nevertheless, ILM should be proud of their work on the fifth Indiana Jones movie. It wasn't flawless, but whenever Harrison Ford stood still, it was eery how much it looked like him playing the character in his prime.

Indiana Jones and the Dial of Destiny is in theaters now.