The Visual Effects of “Black Sea”

by Graham Edwards

Jude Law stars in Kevin MacDonald's submarine thriller "Black Sea"

The submarine movie is a staple of cinema. You might even say it’s a classic sub-genre, with films like Run Silent, Run Deep, The Hunt for Red October, The Enemy Below and Das Boot ensuring its continuing appeal over the years.

The latest director to dive into in the claustrophobic, pressure-cooker environment that is the submarine movie is Kevin MacDonald (Touching the Void, The Last King of Scotland). His latest film, Black Sea, sees maverick Captain Robinson (Jude Law) leading a ragtag submarine crew into the ocean depths in search of a sunken German U-boat rumoured to be laden with Nazi gold.

Visual effects for Black Sea were delivered by Union VFX, whose team had worked previously with MacDonald on How I Live Now. VFX supervisor Simon Hughes oversaw the creation of 170 shots, on a project that ran for approximately a year, and kept a crew of around 30 VFX artists fully submerged in post for three months.

Watch Union VFX’s breakdown reel for Black Sea:

Preparing to Dive

“We referenced a lot of existing submarine films, including Das Boot and Below,” stated Hughes, “but we spent more time studying real footage – generally archive material from all sorts of sources. Reference material for the overall look was shared between us and the production designer, Nick Palmer, including salvage operation photos taken by divers in the Black Sea.”

As well as studying a host of maritime movies, the director drew additional inspiration from a science fiction classic. “For a sequence where a team of divers journeys from the sub to the U-boat, Kevin referenced Alien for its sense of claustrophobia,” Hughes recalled.

McDonald’s interest in the visual execution continued throughout the concept phase. “We did a lot of previs and concept design for Black Sea, and Kevin was very involved in this from day one – especially as it helped with the setup for the tank shoot,” Hughes remarked. “Kevin is very hands-on. Once we were up and running, however, he was happy to allow us to push forward and complete the shots without too much back-and-forth.”

The CG submarine created by Union VFX for Kevin MacDonald's underwater thriller "Black Sea" was based on the former Soviet vessel U-475 "Black Widow", now moored in Rochester, UK.

The CG submarine created by Union VFX for Kevin MacDonald’s underwater thriller “Black Sea” was based on the former Soviet vessel U-475 “Black Widow”, now moored in Rochester, UK.

How to Build a Submarine

The submarine featured in Black Sea was based on the former Soviet vessel U-475 Black Widow, now moored in Rochester, UK. Surveys were undertaken both inside and outside the vessel, and the interior was lidar scanned. “We sourced the technical drawings too,” added Hughes, “which we brought into Maya to build our model from. We also created a separate, damaged version of the sub, that we could reveal using a blend shape during the collisions.”

In all, the digital submarine took about two months to build. Certain parts of the vessel needed to have independent movement – such as cables, propellers and ropes. Most of these were animated in Maya; however, a few were simulated in Houdini, which was also used to add environmental effects.

“The sub needed to generate disturbances to particulate matter and seaweed, create bubbles and so on,” Hughes commented, “so we translated our Maya model to Houdini, which largely involved making sure that all the holes and seams were closed up, otherwise we would have seen FX simulations reacting strangely to the geometry.” Smoke passes were also generated at this stage, so that the compositors could control the turbidity of any given scene.

FX simulations were used to add particulate matter and bubble trails to the underwater scenes, as well as to create specific events such as explosions.

FX simulations were used to add particulate matter and bubble trails to the underwater scenes, as well as to create specific events such as explosions.

Canyon Encounter

As every fan of submarine movies knows, sooner or later the captain is likely have a close encounter with either the sea bed or an inconveniently situated rock wall. In Black Sea, it’s a perilous passage through an underwater canyon that puts Captain Robinson’s crew to the ultimate test.

“To get a feel for the canyon sequence, matte painter Lizzie Bentley did a couple of pieces of concept art,” Hughes recalled. “At the same time, our previs and FX lead, James Roberts, put together a previs sequence to establish angles and timings. This was done in Houdini, partly because that was James’s background, but also because we liked the look of the renders we got out of Houdini/Mantra. We did all this early on, so that as the edit progressed they had the shots in the cut.”

This early stage also saw Union spending roughly two months on R&D, exploring ocean and water effects in Houdini, and making the appropriate improvements to their pipeline in preparation for the demands of the show.

In post, the canyon terrain was created by CG supervisor, Mervyn New, using survey data from the Black Canyon in Colorado. Basic geometry was built up in Terragen, after which the model was further detailed using Maya and ZBrush, with texturing in MARI.

“Instead of over-texturing and sculpting the whole canyon, we waited until we had a first pass,” said Hughes. “After that, we isolated the areas that needed further texturing and sculpting.” Black Sea was the first feature for which Union VFX had used Solid Angle’s Arnold renderer. “We noticed a big improvement in render times and quality,” Hughes observed.

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At a critical moment, the submarine collides with the canyon wall. “That shot was entirely CG,” Hughes revealed. “That includes all the debris, falling rubble and smoke, as well as the relevant collisions between all these objects, were generated in Houdini. As there was such a high level of interaction in the shot, all the CG needed to be rendered in Houdini too, except for the sub itself. So we spent a fair amount of time moving between the Maya and Houdini setups, making sure we were getting the correct result.”

Maria Peralta Ramos, compositing lead, paid particular attention to developing specific underwater looks for the canyon sequence. “These were based on lens distortions and aberrations,” said Hughes. “It took a long time to get the right feeling of murkiness, but still retain enough image to tell the story. It was a challenging, but very rewarding sequence.”

Dive! Dive! Dive!

No submarine movie would be complete without the sequence where the crew has to venture out into the briny. Black Sea is no exception. For scenes in which Captain Robinson’s motley crew of gold hunters embark on a diving foray, the performers were shot interacting with three large set pieces submerged in a tank, with the scenes further enhanced by visual effects.

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“The practical set pieces comprised the front lower section of the submarine – including the first torpedo hatch and the opening hatch on the top deck – and the underwater ridge, which climbed up about ten feet,” said Hughes. “Two weeks were allocated to shoot the diving sequence, with tight turnaround times for moving the set pieces. It was a complicated scene to shoot, so we prevised the entire sequence, working from storyboards done by Dan Maslen.”

The previs footage incorporated clear indications of where the practical sets would begin and end. “We took our model of the sub, and highlighted the sections that would be covered by practical set builds in blue,” Hughes explained. “So, when we rendered the sequences, everyone could see when we would see the set pieces in frame. This allowed us to assess the VFX shots early on, and it helped Kevin, Nick, cinematographer Christopher Ross and Pinewood’s Diving Services to work out a plan for the shoot.”

During the shoot, magnetic tracking markers were attached to greenscreens positioned behind the set pieces; each marker carried an underwater LED light. “We had to be careful about when to use the greenscreens,’ Hughes observed. “When submerged, they influence the overall look of the scene far more than they would in a controlled lighting environment above water. Once we brought up the levels of murkiness, and lit the foreground in a diffuse and atmospheric way, we found the green could sometimes hinder the scene; in these instances, we reverted to using roto rather than key.”

Diving scenes were shot in a tank at Pinewood Studios against underwater greenscreens. Union VFX created CG extensions to add in both the missing parts of the submarine and the surrounding marine environment.

Diving scenes were shot in a tank at Pinewood Studios against underwater greenscreens. Union VFX created CG extensions to add in both the missing parts of the submarine and the surrounding marine environment.

The marine environment also complicated the task of matching Union’s CG cameras to their production counterparts. “We did an underwater lens grid shoot using the correct lenses in the same underwater housing as the production cameras,” Hughes recalled. “This was very important, because the housing – and the fact we were shooting underwater – added an extra level of distortion to the distortion already present in the lenses. Luckily we didn’t shoot with zoom lenses as well!”

In post, Hughes’s team composited the practical sets into their CG environments: “It involved a lot of roto, and then building a set of matte paintings for ground extensions, a lot of which were done shot by shot. We spent a lot of time nailing the correct balance of murkiness and lighting, including matching beams from the divers’ torches, and relighting our CG extensions with the beams.”

For a scene showing the submarine cruising along the ocean surface, a tug boat was photographed from a helicopter, then replaced by Union VFX’s CG vessel. Actors Jude Law and Branwell Donaghey were shot against greenscreen and composited in.

For a scene showing the submarine cruising along the ocean surface, a tug boat was photographed from a helicopter, then replaced by Union VFX’s CG vessel. Actors Jude Law and Branwell Donaghey were shot against greenscreen and composited in.

Coming Up For Air

Reflecting on the challenges of underwater filming for visual effects, Hughes remarked, “It’s about knowing when and where to use the greenscreen, how to get measurements of the set and camera, and how to set up basic things like tracking markers. That’s nothing new, but the difference is that it all needs to be relayed back to the diving team via a remote system. At the same time, multiple instructions are coming through to the team, who are only allowed in the water for a strict period of time.”

"Black Sea" teaser posterFor the Union VFX team, the “Black Sea” experience proved ultimately to be all about the ocean. “I learned a lot about creating underwater environments and CG oceans, how to blow things up underwater, underwater collisions, underwater filming, and how to manage the on-set VFX requirements whilst shooting in a tank or from a helicopter,” Hughes commented. “I also learned a lot about how to tell a story with VFX, and how to help the process along using previs, storyboards, reference and concept art, and just discussing the sequences to work out the narrative.”

Special thanks to Cheryl Clarke. Black Sea photographs copyright © 2014 by Universal Pictures International.

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