Kevin Macdonald’s Black Sea tells the story of a submarine captain (Jude Law) who takes a gig to find a lost sub full of gold. Union VFX handled the film’s visual effects, which included incorporating a CG submarine into both surface and underwater shots. We find out about the work from vfx supe Simon Hughes and vfx producer Tim Caplan. Plus we feature a vfx breakdown of the shots.

Watch the breakdown.

fxg: It really feels like there was a move to try and shoot some things practically. Can you talk a little bit about that, and the approach to filming?

Simon Hughes: That shot of the submarine going out to sea - I’m personally a real believer that we should at least try and get something in camera that we can use as a launching point, and so we came up with this idea together, of actually going down into the Medway in Kent and having a tugboat, which, actually, doing - setting out to sea, which is, we get to the point where we get to the mouth of the ocean, and story-wise, works really well and all that kind of thing.

And I think Kevin, being from a documentary background as well, had a lot more confidence, because he actually got his hands on, and he’s looking at something real and so that helps him out really. So what worked with the tugboat though was, we found a boat which had the overall correct weights in the front, and we worked out the speeds that the submarine could actually sail at, and we got the tugboat to do it at the correct speeds. So you're just working with all these things that are accurate to a degree, and so it's just good. It's a really good launching point.

fxg: Were you shooting with some aerial stunt work or photography or helicopter for those ocean shots?

Simon Hughes: Yeah, it's all helicopter passes, which is a very enjoyable day spent, doing multiple passes over the tugboats, which is literally about four or five hours of doing 180 degree turns, going over it, and all sorts of crazy moves, which - we weren’t feeling too good for at least about two days afterward, I think, when we were done on that. So, it was a very good fun shoot. The biggest shame - that we sort of all felt but then I think it ultimately worked well story-wise, though, is the action - when we went and reccy’d that location, it was - it seemed quite choppy, and it felt very North Sea-like and a little bit daunting.

But when we actually got there on the day, we just had the strangest, calmest day that you have ever seen on the North Sea, and - which is, it’s just so unlike that location. But I think we also felt that it added sort of an eerie quality to it, in the end. If you actually look at the opening shot again, you’ll see it’s just like glass, which is - it’s quite unusual for that location. It’s a lot more choppy.

Tim Caplan: It’s like a lake.

Simon Hughes: It did pose a few challenges for us, obviously, because we needed to put in some - mix in CG water with practical, and you’re obviously wanting everybody to believe that all of this is as real as possible, but then they’re looking at this glassy water and questioning whether it’s real or not. So, it posed a bit of a challenge for us.

fxg: One thing we often talk to you guys about is really that Union’s specialty is the invisible effects world, and clearly these shots are. But here you’ve got digital water, your digital sub, so were you guys sort of ramping things up in your own pipeline and toolset, to be able to do this?

Simon Hughes: Yeah, very much so. We came straight off the back of another film with Kevin, and onto - we did How I Live Now and then moved on to Black Sea, more or less straight away. So I was talking to Kevin, even while we were still on How I Live Now, about the possibilities of the Black Sea and how it was looking like it was going to be the next film that he was going to be working on, and he was kind of pulling me in and talking to me about what this could possibly mean.

So I just basically got together with the Houdini guys here, who had actually done quite a lot of water work before, but I was just a little - said, look, “This is coming, let’s get our toolkit nailed, let’s just really spend some time on it.” So we had a good couple of months R&D time, just to really hone our tools and just get ready for it. So when it did come in, we were one step ahead, I guess.

Tim Caplan: Even then, because we were getting together in production meetings, when they’re trying to work - because there was talk about doing models and things like that at one point, and there was a lot backwards and forwards. So one side of the table is saying, "Look, just do it all in visual effects," one side is saying, "No, you need to do something practical." But what I was able to do, though, was bring tests with me to these talks, and everyone was looking at it going, "Okay, let’s do it in visual effects."

fxg: Let’s talk about the sub build. Was that based mostly or all on concept art, or did you have anything real - a partial build to get textures correct?

Simon Hughes: Well, the luxury with that sub was that it is a real submarine, which is actually moored in Rochester, in Kent. It doesn’t sail anymore, but because we were actually basing everything fundamentally on a real submarine, that’s where we started with.

So we did a full, I’d say, set survey, of every single nook and cranny of that submarine, and photographed all the details, inside and outside. Because there was even talk about us doing work on the inside at one point, as well. When we had the helicopter day, we did flyovers, going over the top of the hub of the submarine, so we could see it all from the top deck, and all the rest of it as well.

Obviously, because it’s an existing submarine, it was pretty easy for us to find all the actual technical drawings, and even though it's just a nice historical reference, actually watching the submarine sailing and doing all that kind of stuff, we want historical references. It was important to us as well, because you will see, in the film, there was a couple of shots that we actually had to blend our CG submarine with the real one. We’ve got the initial moments when they come up to the submarine, to see it for the first time. Then we had to replace things like all the conning towers, and there’s a lot of holes and damage on it, and we had to patch all that in.

fxg: I think you used Arnold for rendering, how has that been?

Simon Hughes: I’d say this is probably our first proper show using Arnold. We were sort of doing it over a bit of A Theory of Everything and this one, but this was really our testing ground with Arnold. So, and we were really happy, actually, very good. Our render times just dropped.

fxg: Because it’s an aged submarine and there was really so much detail in it, tell me about some of the challenges you had where it is underwater and you’ve had to work out how much detail to show, and I guess how much detail through the murkiness?

Simon Hughes: We knew we were going to be seeing the submarine potentially 360. Like, we were previs’ing all sorts of shots to show on camera what the moves would be. Sometimes the cameras - we even had cameras stuck along the submarine, sitting through the water, we had the submarine going right in front.

So we knew we needed to - whatever we built had to be done to a very high standard, 360 degrees. So that was the first thing that we did. And obviously that was all based on the real texture and we needed that to be high resolution, held right in front of your face, basically. And then once - so, we preview the shots, which we get the overall moods now, with Kevin, and then we know that we can handle it quality-wise, because the submarine is built to such a high standard.

And then we went into sort of dialling it, in terms of murkiness, and murky levels. So we had - well, actually, one thing I found when seeing a lot of R&D is, I actually found a lot of stills taken by actual Black Sea divers, that it actually had wrecks at the bottom of the Black Sea. They’re beautiful photographs, it’s just off the website that we found. But we actually took that as an overall launching point, because it makes perfect sense; here it is, real photography, in the Black Sea.

So this is - this set our benchmark for our levels of murkiness and the fall off going into the distance; that impressive nature and murkiness right on top of your head, and how lighting would play down there. There were just a lot of - we did spend a lot of time just kind of doing a few concepts and things like that, and then looking at that sub, at some of these photos, and just talking back with Kevin about how far he wanted to go. It is interesting, as well - I mean, it’s a story point thing, isn’t it, as well.

So much of this film it was okay to be incredibly murky so you are more or less losing everything, it's a very subtle silhouette, almost. But then we had some shots where - just part of the telling of the story, we needed to cheat things a bit, and so you actually see the sub a little bit more. A fine example is when we see the U-boat reveal. They’re sitting on top of the U-boat holding a flare, and the reality is that they - we wouldn’t see anything really, at the distance that that camera has got. But obviously we need to see something, because it’s a key point of the story, so we get into points like that, where we are sort of cheating the level of the murkiness.

fxg: I also thought what was really successful in the underwater shots was the digital sea floor and cavernous environments. Can you talk about how you sort of built those up?

Simon Hughes: It was all built with the Terragen engine, which is - I think it’s part of a plugin in Maya now. So we did initial passes doing just - it enabled us to get something pretty quick out to edit and to block it down in terms of where they wanted to see in there. Once they did, we just basically brought that back into MARI. In all areas that were close enough to camera, we just basically did high resolution texturing, which we just painted out from various elements that we had in our library here, really, in the images section. We just - down and dirty old-school painting.

Then, going around the sea floor again, we went between matte painting at one point - it actually ended up a the full CG build of that floor, with CG rocks and all the rest of it. We just needed to be able to be move and to have that sort of flexibility, and lighting and all the rest of it.

fxg: What about when there's shots of divers shown? I thought it was clearly quite a bold idea to, again, shoot some practical photography in an underwater tank.

Simon Hughes: Yeah - it’s a pretty crazy thing to try and control. See, it’s very difficult, this underwater shooting, because, as much as you try and organize these things in advance, and all the rest of this, as with any shooting, there's a lot of improvising that happens on the day. So, we try and cover as much green as you can. But then also the green screen actually causes - can cause us problems in some shots, because obviously it’s causing a lot of spill down there in the tank, and it’s a very - it’s supposed to be a very diffuse lighting environment. So we kind of made the call, basically on set as we were going through to decide sort of key moments, which we did for green screen in there.

A lot of it, we would actually go back to just roto’ing. It just enabled us to just kind of get the balance right in the tank, the overall level was okay, and then that we knew we could just get in to just kind of cutting them out, ready for that. Trying to - it’s just - it’s even tracking and things like that in the tank is a real challenge. We just designed a lot of underwater LED lights and things like that, so that we could - as they're doing a quick frame-up, we could just get in and throw them in the tank and just try and see where the edges of sets are/

fxg: There’s a couple of explosion shots - how were they achieved?

Simon Hughes: Well, there’s the explosions when we're outside the submarine, where you see the glass actually come outside. That’s all entirely done in 3D, so there’s no practical elements in that. Which is - we’re very proud of that actually, because it’s quite - there’s a lot of R&D about this, we have to - compressing, and going back into an explosion scene, we found out a lot of reference material on that and just spent a lot of time just matching an underwater explosion.

Then the explosions interior again, yeah, they were very much a mix of the practical elements, which we shot with the SFX team, and some elements that we had in the library here, and then just filling it up with a lot of effects to bring in spark and all sorts of stuff really. So yeah, a mixed bag on those things.

fxg: Tell me about the sort of length of the project and how much - how big your team was, on it?

Tim Caplan: I think we were probably on it from - well, it’s a good question. We were probably on it for over a year, from start to finish. So we were involved at the previs - we previs’d the whole underwater sequence, where they travel from the submarine to the U-boat. I suppose the team just steadily grew throughout the job to when we probably were up to about 30-35 people on the show.

fxg: Is there anything else you wanted to mention about the show?

Tim Caplan: I think that, from our point of view, it was a perfect show for us, in terms of how the production engaged with us. And it’s definitely the kind of work we’d love to do more of.

Simon Hughes: It’s just been really good fun, with the people who were in it. It’s rewarding work. It comes under the invisible effects category, but it is far more challenging, and you have full scenes of 3D shots in there. So there's a lot for us to be proud of, I think.


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