Galactic footsteps in the cosmic rewind: Scanline & the Flash

Zack Snyder’s Justice League, often referred to as the “Snyder Cut” is the 2021 director’s cut of the 2017 film Justice League. Like the theatrical release, Zack Snyder’s Justice League follows the Justice League – Batman (Ben Affleck), Superman (Henry Cavill), Wonder Woman (Gal Gadot), Cyborg (Ray Fisher), Aquaman (Jason Momoa), and the Flash (Ezra Miller) – as they attempt to save the world from the catastrophic threat. Steppenwolf and his Parademons return after eons to capture Earth. However, Batman builds a team with the help of Wonder Woman, to recruit and assemble Flash, Cyborg, and Aquaman to fight the powerful new enemy.

Unlike the theatrical release, the film is much longer, a different aspect ratio, darker, and a much bigger hit with fans of the DC universe. Snyder had originally stepped down during post-production following the death of his daughter, and Joss Whedon was hired to finish the theatrical version, completing it in ways quite different to Snyder’s script.

Bryan Hirota, VFX Supervisor at Scanline has worked extensively before with both Director Zach Snyder and VFX Supervisor John Des Jardin, but in the case of the Director’s version of Justice League, the revisions to the film were almost a film within themselves. For the new 4-hour film, only one hour of footage was used from the first film untouched. Scanline completed their work in just 7 months to help Snyder bring his version of the film to an audience. The first month of that was just trying to uncompress and bring back online the archive of the original files from 2017.

One of the interesting sequences in the new version was the rolling back of time by the Flash, undoing the apocalyptic nightmare, by moving faster than the speed of light. This posed a range of problems. For the audience, the flash needs to move forward, while the world is moving backwards. To denote speed, the Flash is moving in slow motion, so the world is unexploding backwards in slow motion, reforming around him. Additionally, the director had a very clear idea of what he hoped to see in the final sequence. “Zach had the idea of some sort of representation of the unity explosion, and energy, as Flash was rewinding all the destruction backwards,” comments Hirota “He also had this idea of his footsteps creating like a galaxy with each step, which he described as being ‘like a mini big bang’ on every step”.

Hirota and the team were keen to explore this new visual problem and build on past work they had done with the character. The team started doing effects, tests, and simulations. “We were exploring what it meant to do a mini big bang on each, on each footfall,” he adds. The team nicknamed the effect: ‘the galactic footsteps in the cosmic rewind‘. But the Scanline team quickly discovered that this rewinding of explosions around the Flash was not as simple as playing a simulation backwards. To make matter worse, the idea seemed so strong that the director decided to accelerate that process by putting two or three of these shots in the original ‘hallelujah’ trailer. (See below @ 2:00) “That whole period is a gigantic blur,” jokes Hirota. “From the time we got the go-ahead to do the (revision) project, to the time that the first trailer came out wasn’t that long, maybe it was a couple of months!”

Shocking Frankenstein’s Monster

Projects at Scanline are well archived and carefully catalogued, but even so with the changes in both staff and technology that had happened since the original 2017 project, “we spent the first month just trying to “shock Frankenstein’s monster back to life”, mused Hirota. Scanline VFX, as a facility, had not worked on the original footage shot in Russia, but in reality, as most of this was digitally created from a clean sheet design, it was easier than some of the revision to previously crafted shots. For example, the Scanline faced not being able to load some old assets as the newer versions of the pipeline would not read the files completely accurately, and even on a normal project, done under the best conditions, it is exceptionally hard to pick up a complex shot from another artist and take over blind, – let alone when the first artist no longer is on your team and used a different version of the software. “In general, if there were an old shot that got brought back, then it required some forensics to understand even what the aim was of the shot,” spells out Hirota. “We would start by gauging where Zach was with the shot.  If Zack 90% happy with it, but we need to fix X, Y or Z on it, then we tried to figure out the minimally invasive surgery we had to do. But still, sometimes we would get stymied by some software that just was no longer compatible or some scene file.”

If all of this was not enough, the Zach Snyder version was mastered in a different format. The new film is in a 1.33 aspect ratio vs the original which was 1.85. This meant that some shots that might have been perfectly acceptable, inside the 1.85 region, needed to be worked on to bring the parts of the frame outside the 1.85, but now seen in 1.33, up to final quality.

Likely for Hirota, while some team members had moved on to other projects, the senior team leaders in Scanline’s VFX team were mainly the same on the new version as the old. The project was comped in Nuke, with the animation in Maya and most of the effects done in 3DSMax, “using Houdini as well to destroy things. And then we used Scanline’s Flowline to do a lot of fluid dynamics simulations on top of that,” he outlines. The team grew to over 400 artists at its peak, which was a third again larger than the team on the original.

Sims Backwards.

Scanline is known for its outstanding work in simulation, but the sims needed to look good in reverse and that required more than just playing forward-sims backwards. The normal approach with destruction sims is to do the major simulation and then build tertiary sims onto it with very bespoke elements. What the team found was that the dust passes in particular needed to respect that while the explosion was running one way in time, The Flash was going the other, and for him to be seated in the shot, his forward motion needed to also be reflected. “You could argue that time and thus direction was ambiguous. But the backwards traveling effects could end up in inconvenient places or unattractive places in the shot in the time,” He says. “And also the ripping apart of geometry, in reverse it can look too neat.” The fact the audience can see where the destruction is going changes how the eye reads the scene, naturally, there is no sudden surprise as large amounts of debris fall back into place. If pieces seemed too predictable in their reassembly the shot was less cinematic, especially as this was happening in reverse.

The performance of the Flash was key as the plot turned on his ability to save the day at this point and overcome his guilt at allowing the death of his friends. The actor, Ezra Miller, was shot in a suit with interactive lighting, but because the digital environment changed with the light, Scanline, “ended up replacing his suit almost entirely in this scene, so that it could react to whatever flash speed effects we were creating and adding to the world around him,” says Hirota. “And in a handful of wider shots, the character was fully digital.” Scanline took great care to preserve as much as they could of the original actor and to match to Ezra (Miller’s) great performance.”

There are some shots in this sequence where Miller was delivering dialogue, but still in slow motion. For these Miller mimed the lines which were sped up on playback in the studio. This meant that when the footage is played back in slow motion the words would appear to be said at the correct speed, while Miller would be moving in slow motion. Most of this style of footage was shot at half-speed, (48fps for 24). As effective as this is there were still some shots where the director noticed the ‘mime’ and the Scanline team would correct the issue.

And much more….

Flash was only one of many sequences Scanline VFX worked on, for this new four-hour version. For example, they redesigned the costume or skin of Steppenwolf, making his skin ripple and become a reactive armour that reflected his moods with spikes, metal scales, and feathers as well as changing his dialogue delivery.

In all, Scanline VFX delivered over 1,000 shots across 22 sequences, with their work encompassing everything from hero creatures, character builds and digi-doubles, to large-scale environment work and epic battle/fx destruction sequences