How Christopher Nolan’s Tenet used visual effects to invert time

Award-winning filmmaker Christopher Nolan is known for crafting compelling stories filled with stunning visual elements, and his latest movie, Tenet, is no exception.

The story of a talented special operative played by John David Washington who’s recruited by a mysterious organization to save the world, Tenet has its characters grapple with the concept of inversion — the ability for people and objects to move backwards against the flow of time. From bullets that fly into guns and vehicles that drive backwards to buildings that implode rather than explode, Tenet features a wide range of scenes that make clever use of inversion while telling a deeply layered story of high-stakes espionage.

Working alongside Nolan on Tenet was visual effects supervisor Andrew Jackson, who previously worked with the acclaimed director on 2017’s Dunkirk, and earned an Oscar nomination for 2015’s Mad Max: Fury Road. Digital Trends talked to Jackson about his work on Tenet and how he found the balance between practical and digital effects in order to turn back the clock.

This article is part of Oscar Effects – a 5-part series that puts the spotlight on each of the five movies nominated for “Visual Effects,” at the 93rd Academy Awards. The series explores the amazing tricks filmmakers and their effects teams used to make each of these films stand out as visual spectacles.

Digital Trends: Christopher Nolan’s films always seem to have much fewer visual effects shots than you expect, given what you see on the screen. How many visual effects shots were in Tenet?

Andrew Jackson: It was slightly under 300. That’s fairly typical for a Chris Nolan film. Working with him is a very collaborative experience, though. We collectively look at all of the effects, whether they’re visual effects or special effects, and approach everything holistically when looking at how best to achieve something for the film. I work very closely with Scott Fisher, the special effects supervisor. I used to do practical effects myself, building miniatures and such, so I’m very comfortable in that space and finding the right combination of visual effects, practical, and CG. And if it does need to be a visual effects shot, we find ways of using as much filmed material as possible, which works very well with Chris’ aesthetic.

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What were some of the sequences in Tenet that did rely on visual effects work?

The biggest thing was the finale battle scene. There’s a big building that’s simultaneously imploded and exploded. It sort of rebuilds itself [in the scene], only to be destroyed again. And we did that in a very collaborative way with special effects. We built two large, one-third scale, 10-story buildings. We then blew both of them up — one at the bottom, one at the top — and then reversed the footage of one of those. We filmed them from two matching cameras, so we could reverse the footage of one and composite them together. That created that illusion of a building that’s simultaneously exploding and imploding, and was probably one of the biggest things for the visual effects team in the movie.

On the surface, many of the effects just seem like you’re rewinding the footage, but when you look closer, you realize it’s much more than that. What sort of challenges did the film’s time-shifting element present?

One of the biggest challenges for everyone working on the film was just getting your head around what was happening at any point in time. It would have been lovely if it was just a case of filming everything and then reversing it, but we always had forwards and backwards action in the same shots. So only half of the action could be performed normally, and the other half had to be performed in reverse. So what we did was to get a lot of the actors to learn their performances in reverse. Their half of the shot would be performed backwards, and the forward people would perform forwards.

Sometimes, though, we would have to reverse the whole thing. We would decide which elements were going to be the hardest to do backwards, and then we would let that be the forwards action [when we filmed]. The people who had the easier jobs would then end up performing backwards in that shot, and then we’d reverse the whole thing at the end to get the most difficult parts working the way we wanted them.

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Was there anything new you learned or appreciated more in working on this film’s unique time-shifting shots?

Early in preproduction, I set up a little previz scene [a conceptual, 3D visualization] of the car chase scene — because in that scene, there are cars and people that are moving forwards and inverted. They interact with each other, and people who are both inverted and forward cross from one car to another car, and sometimes the cars themselves are inverted, driving backwards and forwards. There’s also a case that’s thrown from a forwards person to an inverted person, so it’s a really complex interaction between the forward and the inverted worlds. The audience sees this scene the first time from the forward point of view, and then later on in the film, we go back to the exact same scene, inverted, and see it in reverse. We see all the same events again, this time from an inverted point of view.

It was really vital that all of those stories work and the logic made sense in both directions, so it turned out that tool — that visual effects previz tool — was incredibly valuable. [With previz], we could test out those key moments in time and space, and then go through that forwards and backwards and check that they worked in both directions. And it really was the only way we had of doing that.

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Because it’s not something you can just explain on the fly as you’re directing a scene …

No. And it was a really difficult thing to even do on paper, because you can’t incorporate the exact timing of everything on paper.

We had these previz scenes on a laptop that became vital whenever we were filming any of the scenes that had complex inverted and forward action. This laptop with the 3D scene on it became our reference, so we could quickly go and say, “OK, while that’s happening, this should be happening.” That was really important for a lot of those scenes — especially the car chase scene and also the scene where the plane crashes into the building. There’s a really complex set of interactions going on inside the building when that plane crash happens, because there are multiple versions of the same characters inside the room at the same time. So it was a really valuable tool there, too.

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You mentioned the plane crash, and it was a bit surprising to learn that the 747 crash scene was filmed in-camera and not a visual effect. What does your job become in a scene like that, with such a spectacular shot with minimal visual effects?

As always with Chris, we put effort into trying to achieve as much of it in-camera as we possibly can. With a with a scene like that, we look at the various options from one end of the scale to the other. On one end, there’s the full CG plane crashing into a building as a CG effect, and then in the middle somewhere, there’s the option of building a miniature plane and crashing that into a miniature building, and then at the other end of the scale is using a full-size plane and crashing it in-camera, and then augmenting what you’ve shot.

In that particular situation, there were a lot of scenes leading up to that point around the plane, on the tarmac, and inside the plane, so we needed the plane to film everything leading up to it. And by the time you’ve gone to an airport, got a plane, and you’re filming in and around it, it was a relatively small step to continue on with that and do the final crash. So we built the set for the plane crash at the airport where the plane was, and we towed it with a couple of big trucks. The visual effects aspect of that was cleaning up the tow ropes, getting rid of any interaction between the tow ropes and things on the ground, and adding that jet blast effect as it drives through the car park.

The inverted bullet shots are particularly fascinating in the film. What was development like on that effect?

We did quite a lot of work on the bullet hits. There was always the desire to make it feel as grounded as possible and not be fantasy or magic. So the question arose of what an inverted object looks like when it’s interacting with the forward-moving world. Obviously, the bullets have to come out of the wall and into the gun, so that main event is inverted. But how long does the bullet hold, being in the wall? And what does that look like when that moment is forming? The bullet hole needs to appear at some point, right? It couldn’t have been there since the building was built. So we experimented with various ideas and we spoke to Kip Thorne, the theoretical physicist who Chris has collaborated with before on other films.

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There’s a theoretical basis for this inversion effect?

Yes, there is a theoretical idea that it could be possible for entropy to run backwards. So it’s not total fantasy. The whole thing is based on this idea that it is indeed possible. We then came up with this idea that an inverted object interacting with the world might have a sort of 70/30-percent pushback from the world when it’s happening. So the way that looks in the film, if you look really closely at some of the bullet hits, you’ll notice there’s a little debris falling before the bullet hit happens, and then again afterward. There’s a tiny little bit of forward, real-world effect on this inverted event.

I think that really helps to tie those things together. You’ll see that 70/30 idea when there’s a big explosion or when a car blows up, too. There’s a sort of pushing back of time from the real world on the inverted effect.

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Visual effects are often at their best when the audience doesn’t know they’re looking at a visual effect. Was there a visual effect in Tenet that you’re particularly proud of that audiences might not realize was a visual effect?

What I really like is when people don’t know whether something was CG or practical and how it was achieved. Towards the end of the film, there’s a scene with a lot of of land mines, with a vehicle driving up a hill and land mines going off. Some are inverted land mines, and some are forward, so there’s a combination of some of those filmed in-camera and some of them CG to create the scene. Blending those two together so you can’t tell the difference is key.

We also added CG helicopters into a couple of scenes, and all sorts of small things that I think people won’t know are effects at all. In the yacht-racing scene, for example, there are a couple of shots in there where we had to tow the boats without masts because of safety issues with the actors, and we had to add CG masts into those shots afterward.

Christopher Nolan’s Tenet is available now in select theaters and as a streaming rental or on-demand video.

This article is part of Oscar Effects – a 5-part series that puts the spotlight on each of the five movies nominated for “Visual Effects,” at the 93rd Academy Awards. The series explores the amazing tricks filmmakers and their effects teams used to make each of these films stand out as visual spectacles.

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