High-wire training undertaken by the film’s star Joseph Gordon-Levitt, lengthy pre-vis, a green screen studio in Montreal, simul-cam setups, stunt doubles, face replacements, meticulous replication of 1974 New York and the Towers (including hand-animated traffic!), innovative cloud rendering, and well-planned out stereo – at a “very responsible” budget. We take you, step by step (pun intended) as to how Atomic Fiction, led by visual effects supervisor Kevin Baillie, reproduced Philippe Petit’s daring high-wire act between the Twin Towers of the World Trade Center on August 7th, 1974 for Robert Zemeckis’ The Walk.
To portray Petit’s death-defying walk convincingly, several methods were adopted. Gordon-Levitt was trained by the actual wire-walker himself just prior to shooting, and continued training during photography. For scenes on the wire, production utilised the actor, or his stunt double, on a real wire, on special planks aka the Canadian Bar.
One challenge faced during shooting was the cross-over between the pre-visualisation, actual partial set-build and assets that Atomic Fiction had begun the film’s digital construction on. “We had pre-vis (pre-visualisation) assets from the original pre-vis that was done,” notes Baillie. “But then we realised they weren’t the same as the set build that had been done off of blueprints of the towers. We had to figure out where the differences were, take the pre-vis assets, tweak it to match the simul-cam just enough so that we could rely on it on set. Then in the post-vis (post-visualisation) there was another round that went into it, but Atomic Fiction had started building the hero assets by then and could contribute some of those dimensions to the post-vis team. By the end of the process we had a model that was a dead nuts match of the set build and the entire building.”
Zemeckis leaned heavily on the 3D side of the final image to help immerse the audience in Petit’s world, both between the towers and in many other moments, during the film. To do this, he shot in mono. “I think that’s a very important distinction to make, and we had several meetings early on to make sure that everybody from Bob through to set construction were clear on what the rules were on 3D for this film. Bob really respects 3D as a tool and wanted to make sure we got it right, even though we were doing a conversion, that he got the film-making and lighting and focus, and what compositions worked. He also had to consider how he would cut the movie, he was thinking about editing while shooting.” Legened3D handled the conversion work, taking packages of final comps from the VFX vendors and layering them together within the desired stereo budget. “Interestingly,” notes Baillie, “there are only 826 shots in the movie in total. Some blockbuster films have 2200 visual effects shots. But Bob wanted to make sure that for the 3D to work he would give the audience time to take in the environment and feel it, which works better in stereo.”
Although this article concentrates on the main wire sequence, The Walk also included significant visual effects contributions from two other vendors – Rodeo FX and UPP. Rodeo delivered effects for several Twin Towers ground level scenes that had been filmed only on partial sets, as well as the shots of Petit narrating the film upon the torch of the Statue of Liberty. UPP handled Paris sequences that were filmed in old Montreal, Petit’s early wire performance at a park in France (filmed almost entirely on green screen), and his walk between the towers of the Notre Dame cathedral (again a green screen stunt).