It was only during the filming of Avengers: Age of Ultron that Marvel first began to consider adding the Hulk to the next Thor film. With the distribution license for the Hulk sitting with Universal, Marvel knew they could rule out a solo Hulk movie. But if they incorporated the Jade Giant into Thor: Ragnarok as an ally, they’d be able to finally use one of the most beloved Hulk arcs of them all. They’d be able to adapt the fan-favorite “Planet Hulk” arc and pit Thor and the Hulk against one another in combat.

But how do you actually film such a scene? Speaking to the D23 Disney Fan Club, Thor: Ragnarok‘s VFX supervisor Jake Morrison has just explained how they made that main event so thrilling. It involved forgetting everything they’d learned before and pioneering a whole new approach that took advantage of the very best CGI technology.

The fundamental problem was that the Hulk is tall; specifically, 8-feet, 6-inches tall. That makes it very difficult to film a scene in which he’s interacting with another character. The last time Hulk clashed with Thor, in The Avengers, Marvel made it work by hiring a tall stuntman. They gave him a backpack and a gigantic Hulk head and then used CGI to transform the stuntman into the Jade Giant. Unfortunately, that was less than ideal, as it meant when the actors swung punches at one another, their shoulders would only be inches apart. It took serious animation work to make the scale seem accurate.

An unforgettable clash. [Image by Marvel Studios]

Morrison decided to take another approach. Instead, he scaled the Hulk down to a height of six-foot-two, which meant finding a stuntman to play Thor who was four-foot-two. They hired stuntman Paul Lowe, who usually doubles for child actors, and had him play the part of Thor when they initially filmed the scenes. The fight was carefully choreographed, and then Chris Hemsworth went through his part in front of a blue screen. All it then took was a little digital magic to overlay Hemsworth’s performance on Lowe’s. Morrison is clearly delighted with the finished product.

“When we took the mo-cap Hulk and the blue screen of Thor and clicked the two together, they dovetailed so you get this fight that feels like they’re fighting at the proper scale for the first time. It could have been a terrible idea, but it turns out it actually works—and we think that’s the first time anybody has done anything as crazy as that.”

As Morrison reflects, modern CGI work is “a bit more like jazz.” It’s a matter of trusting your instincts, thinking outside the box, and giving your craziest ideas a chance. In this case, it worked out perfectly, and the result is a scene that’s a clear highlight in Thor: Ragnarok.

[Featured Image by Marvel Studios]