Behind the shoot and VFX for that dynamic train opener to ‘Citadel’

Behind the background plate and bluescreen train carriage shoots.

The first episode of Citadel, now streaming on Prime Video, includes a dynamic train journey set in the Alps, complete with close-quarter fist fighting featuring stars Richard Madden and Priyanka Chopra Jonas and an equally dramatic train crash.

To craft the Alp backgrounds seen outside the train windows and for wide exteriors, the show’s visual effects team orchestrated an extensive plate shoot in Norway.

DNEG then built the train journey environment completely in CG.

In this interview, befores & afters asks Citadel visual effects supervisor Wes Froud and visual effects producer Scott Shapiro to break down the train scene plate and data capture shoot, and the final VFX work.

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b&a: One of the things I’m always interested in for a sequence like this is methodologies and thinking about and planning how you would actually pull this off in terms of filming it, and then what sort of visual effects would need to come at the end. What were the different discussions that you both had about how you would pull this sequence off?

Wes Froud: It was a big undertaking. I mean, you’ve seen the scale of the show. It is television, but it’s big-scale television. So the Russo brothers who produced this, and the showrunners, had very high expectations of what this sequence would be, and it all started from production design.

We were working closely with them and they proposed a futuristic bullet train through the Alps that was very much an observation car. Typically, we would go and shoot driving plates on a train track, we’d shoot plates in the background, but with that production design, we just couldn’t do it. We see floor to ceiling, we see up, we see left, we see down. So we really had to try and come up with a different methodology. Working closely with the DOP, he had a lot of lighting gags that he wanted to add like flickering trees and the sun being extremely low and a very warm look.

Priyanka Chopra Jonas as Nadia Sinh

We looked at virtual production as one possibility, but within the timeframe that we had, it wasn’t really plausible. Then we thought, ‘Do we go shoot plates? Where do we do this?’ I think we came to the decision that this background needed to be a full CG environment. What does that allow us to do? It just gives us a lot of flexibility on the film set.

The thing is, the Russos and the team, they move extremely quick. They’re very well-versed at this, coming from their Marvel background and working very closely with the stunt department. This moves really quickly and just by going full CG in the background allowed us that flexibility and that methodology of giving the filmmakers a lot more freedom to do what they wanted to do rather than going, ‘Hey guys, we’ve got some parameters we have to stick to. It’s got to be over shoulder, over shoulder and we can’t do anything else.’

With that in mind, we found a location which was a place called Flam in Norway, which this whole environment is based on. We went in and we built a 50-kilometer full CG environment, all the way from the same trees, the same rocks, to the same dirt, shrubs. Everything was there.

Richard Madden as Mason Kane, Priyanka Chopra Jonas as Nadia Sinh

Scott Shapiro: It was two weeks of a data capture team divided up into a couple different subgroups. We did everything from man on the ground with 5D cameras, getting textures, moving down the railway line, to drone photogrammetry, at high heights and low heights to make sure that we were able to capture above and below the train area.

Then we also did traditional Lidar, so we could get a point cloud and some reference to then project that and build those textures back on, too. That was about a two-week endeavor in between some bad weather to make sure that we got the sunny days. It was meant to be the Alps in summertime.

b&a: Was any of that with classic array plates or was it more, as you say, different methods used to build up an environment?

Scott Shapiro: The data capture was very much ‘hosing down’ that environment and making sure that we were just capturing everything, then coming back with a library. None of it was used one for one. It was all rebuilt in CG, so that we could move along it at speed.

It’s a train moving 200 miles an hour. We want the trees to react to the train moving by. So when you’re looking out that window and you’re in the observation car, things are whizzing by and things are moving. We knew we wouldn’t be able to get that or get a continuity if we just shot plates. We just moved so quickly through an environment that we’d have no continuity. So it quickly became apparent that the way to approach it was to just rebuild the entire thing in CG.

b&a: When it came time to actually film actors on the observation car and in the train, was that just a train car set against bluescreen or greenscreen?

Wes Froud: It was, yes. It was against traditional bluescreen. I think the key to making this successful was really about the lighting. We worked really closely with the DOP and the lighting department. I mean, it’s just a train full of glass. You can see cameramen, there’s reflections everywhere. You can see the guy doing the coffees in the background. We just had to make sure that none of that was in camera.

Scott Shapiro: There were three different cars on the bluescreen stage. There was the dining car, the observation car, and then a smaller set that was the bathroom set. All of these had lighting rigs outside of them. There were some lighting cues we baked in, such as the sun setting. And then we had lights on a rig that would chase along at a rhythm.

b&a: When it came time to show some external exterior shots, including the guy getting thrown out and then the crash, what were some of the challenges there?

Wes Froud: We always have to start with realism. So we start to simulate tests. We build all these guys as full CG digi-doubles based on cyberscans. Then we just start simulations. We have to start real-world, because if we don’t, we could go down any path. So we’ll start throwing a guy out of a window at 200 miles per hour and let’s see what happens. And sometimes you get good results and sometimes you don’t.

b&a: For the interior fights, I wondered if there might have been some nice invisible effects work there, just in terms of bullet hits or making punches land or anything else that just enhanced the hand-to-hand combat.

Scott Shapiro: Yeah, I love the invisible effects and yes, there’s a good amount of that. Priyanka and Richard were such good partners. They were very much game to do the training, to do the rehearsals, to study the stuntvis. And they would do a take and rush to camera and look at it and tell us, ‘Oh no, I can do it again. Let’s go again. I think I can do that better.’ A lot of it is movie-style fighting, so sometimes some of the invisible effects would be tightening up punches, just bringing things a little bit closer.

There’s a stunt guy who hits what would be a pane of glass. And on the day, there wasn’t glass there. So we added a pane of glass there and made it break. We’d also add things to the tabletop that weren’t there. So when she pulls the tablecloth off, there’s more stuff that flies. It’s little things that you wouldn’t expect.

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