BlueBolt worked as the sole visual effects vendor on ‘The Imitation Game’,Bluebolt-imitation-game16a
creating realistic, invisible VFX for shots depicting U-boats, aircraft, tanks
and streets during wartime in WWII.

BlueBolt Plays ‘The Imitation Game’

BlueBoltcame on board as the sole visual effects vendor on Morten Tyldum’s film ‘The Imitation Game’ about Alan Turing’s code breaking project during WWII, starting on pre-production about eight weeks before the the shoot began. The team’sVFX Supervisor Stuart Bullensaid, “This was one of the tightest budgets we have worked with, but the script was so good that we could not pass up the opportunity to work on the film.” Their team has now been nominated for their work in the2015 VES Awards.

“During pre-production we mainly focused on making sure that Morten’s expectations from visual effects could be achieved within this tight budget,” Stuart said. “The shoot took place at several different locations around England, and we had a chance to visit the sets for all VFX shots and be involved in parts of the technical exploration as well. We also headed out after the main shoot with a reduced camera unit to get more plates for additional shots that started coming up.”

Air, Land and Sea

World War II military vehicles – on land and in the air and sea - were key visual elements of this wartime story. Fortunately, the director made it clear from the start what he was looking for in the project, and had storyboards produced for underwater shots of German U-boats and various war ships at sea.

“Morten also had a clear vision of the types of aircraft he wanted for the story,” Stuart said. “Because a reconnaissance plane was needed for the first aircraft seen in the film, with a little research we found that the Dornier airplane was ideal. We created a handful of variations of this plane in flight, some with stronger turbulence than others and each one was rendered from a different perspective. A side profile was the one that worked best for Morten. We used real photography for the skies, along with filmed elements of rain and smoke to give the feeling of atmosphere and speed.”


The audience gets a view through binoculars over the sea as well, as the pilots would have seen. For an authentic look to base the shot on, BlueBolt’s team found references online of photos of convoys taken from aircraft from that period. They started with filmed elements of seas in order to create a plate large enough to cover the planned binocular move.


“For the lead ship, we photographed HMS Belfast, a British WWII Navy ship now permanently moored in London on the Thames. To achieve the correct angle, we shot it from the Shard, a 300m skyscraper in London, and then had a matte painting artist alter this image so it matched the ships that were accompanying the convoys in the Atlantic. For the other ships, we researched what the rest of a convoy in the Atlantic would look like in WWII,” said Stuart.

“One of our compositors then animated the ships in the water along with their wakes, plus the added smoke coming from the ships’ funnels. At this point the shot was still static so the artist applied motion to the composite to give the impression of a first-person perspective. Rain was added next - this was a combination of rain elements shot against a black screen, and 2D rain created and generated within Nuke.


“Once the cloud cover was established, we moved on to the lens effects such as chromatic aberration, lens distortion and dirt and scratches. All of this helps sell the look of viewing through binoculars and the airplane’s canopy. Finally the vignette of the binoculars was introduced with some internal lens lighting that animated with the movement of the background.”

Another maritime shot shows three soldiers at sea in heavy, stormy weather on the deck of a convoy ship that was, again, based on the HMS Belfast and then manipulated by a DMP artist to resemble historically correct ships after carefully researching all ships recorded to have sailed in the Atlantic in convoys. They also needed to consider the size of the convoy and, therefore, the distance to surrounding ships. “We wanted the convoy to be large enough to give the shot some impact but not so big that it looked unrealistic, so it was really a numbers game that resulted in the distance to the next ship that you see,” Stuart said.

“Our elements library supplied most of the elements required for these stormy weather shots, but as the shot developed in post we realised that the lighting on the soldiers was too bright for the scene that we wanted to create. So we were able to grade down the highlights to a certain point just before they become clipped. We included a brighter patch of light in the intro shot where the camera is looking up at the soldiers, that way we could explain the lighting direction that was coming from their helmets.”

 Stuart explained that BlueBolt always pushes to incorporate real elements into their effects work as far as possible, and these naval convoy shots were no exception. “Where you see ships breaking the surface of the water, we used filmed elements of ships doing just that,” he said. “We used our Canon 5D camera to film boats out on the Thames. These wakes, of course, would be too small for a battleship but once you layer up enough of them you can sell the scale of the larger ships.”


To manage the exterior scenes we see through train windows, captured after the main shoot from a low loader in the English countryside, the crew aimed to avoid filming objects too close to camera to limit the number of shadows to be added to the interiors in post. The artists introduced shadow interactions from passing trees onto the interior by rotoscoping shapes and animating them throughout the scene. To ease it into the lighting exposure of the interior, additional grading was applied to the exterior environment.

Going Under

The transition from the ocean surface to the underwater encounter with the submarines involved still other, interesting challenges and approaches, including taking the camera down to look across the surface and then duck under it. They used a reduced camera crew to film the sea from a jetty. The camera was rigged on a crane giving full control on the timing of dipping the camera under the surface. This had to be timed to sync with a wave crashing over the lens to create a quick wipe from plate to VFX environment.

The foreground ship is a 3D model with projected textures. Live action extras were shot on green screen and used to populate the deck. The remaining ships were digital matte paintings animated in 2D, and the team’s rain effects and sky replacement added to the ominous mood of the shot.

Stuart said, “Once we got into post, the U-boats became much larger in frame. The design of the sub matches that of the Type VIIC/41 U-Boat. We modelled all the larger characteristics of the sub in Maya and the extremely fine details such as rivets and distortions in the metal panels that make up the hull was created with a combination of modelling, displacement maps and highly detailed UV textures. These textures gave the U-boats their beautiful weathered look, all the way down to rust emanating from the rivets.

Submarine Animation

“Animating submarines is actually a hard thing to sell. When travelling forwards, there is little motion in the fins, so the propellers may be the only moving part visible at a distance. In order to sell the motion, we played up the depth that the sub was travelling through and the parallax with the other U-boats. The propellers were rigged in a way that matched the real thing. Therefore, if it were turning left, the right propeller would rotate faster than the left. This effect is most visible in the shot where the sub is travelling away from camera.”

Besides matchmoving a water plate, which is also very tricky, one of the other challenges was creating the lighting for all the submerged shots. Realistically, an observer would see very little in terms of depth from camera. Possibly one U-boat would be visible, but unfortunately that wasn’t going have the desired impact - they needed to reveal the full wolf pack of subs.

“Taking a little artistic license, we tweaked the depth to where we can just make out the pack but still retain the oppressive, murky feel that Morten wanted,” said Stuart. “A combination of filmed elements of dust and Nuke-animated particles created the plankton and general floating particles that you expect in the sea. The bubbles were created in 3D and these were used for the entry of the camera into the water and for the torpedo release.



“We were lucky enough to find some footage of submarines in use and also some torpedo firing tests. What we found was that subs didn’t create a bubble path behind it, like you often see in movies. Also, the release of the torpedos had two stages of bubble creation that we wanted to mimic. First, when the chamber inside the sub opens to release the torpedo, a small amount of air is released. Second, you see a fine bubble trail caused by the torpedo propulsion. So, we played this up beyond what was accurate in order for it to read better on screen. Furthermore, because all the vessels are travelling quite slowly in the scene, we build the drama with the camera motion and the way the environment reacts with it.”

Postvis Tanks

Back on dry land, Bluebolt needed to transform a shot of green countryside to a battle scene featuring several tanks. However, as this shot was not imagined until post production, all the tanks had to be modelled, textured, rigged and animated from scratch. The 3D artists researched footage of such tanks in action and proceeded from there, despite the fact that that one of the tanks had to be shown slowly rumbling past very close to camera.

“Ideally a practical prop would be best to achieve a shot like this,” said Stuart, “but filming had wrapped and post was underway when it was conceived. As we had no live action to begin with, we started with previs of the tank. Once we had the composition looking right, the key to making this work was the rigging and animation of the tank. Each individual tank track needed to move independently with a weight heavy enough to sell the scale of the tank.”


A texture artist, working mainly in MARI and Photoshop, created the camouflage paint job, dirt and mud, which was then added to the model of the tank and then the rest of the CG passes were created - specular, diffuse, normals, position, occlusion and so on. Mud, fire, and smoke were all 2D elements. The mud on the ground was a combination of DMP stills, filmed elements of mud and CG mud.

The CG mud was used especially for the interaction with a lone helmet, seen sinking into the dirt as a tank rolls over it. Stuart said, “The helmet idea came from one of our discussions with the director. It was one of those moments where the phrase ‘wouldn’t it be great if...’ was mentioned. Previs once again gave us the timing of the tank we needed to force the helmet down. Our 3D team animated the helmet being crushed and forced into the ground, and CG mud around the helmet helped with its integration into the rest of the composite.”

Bomb Site

The movie’s bombed out street scenes took more research, and were created from plates shot in central London near Chancery Lane. The set dressing was added at street level, excluding the bombed out buildings and any destruction above head height, all of which was added in post. “A central London location like this carries many restrictions about what the set dressers could touch,” Stuart explained. “Therefore, dirtying up the buildings at street level had to be added in post as well.



“Our challenges for this involved selling a shot in which the all the mayhem had occurred a day previous and life as they knew it was continuing. Beyond the obvious devastation, we had to show the serenity of London where life gets back to normal. The street consisted mostly of 2D elements. Due to the camera move we projected the majority of the matte paintings for buildings onto 3D geometry to allow for accurate parallax. Fire and smoke had to be subtle, and it was more about adding in the smaller details.

"Examples of this would be a man sifting through rubble in a hollowed out building, rubble still breaking away from weakened walls, and the finer details of office furniture still in their rooms but clearly visible, as the walls no longer exist. Virtually all of the people were included in the main plate. Just a couple of extra actors were shot separately against blue screen and added on top of hollowed out buildings, searching through the rubble.

“We had a couple of shots that required sky replacements but we needed to keep close to the exposure and general grade of the original sky in order for it to sit in correctly. All too often sky replacements are noticeable and that mostly comes down to the changes being too great. Subtlety was the key here.”  

Words: Adriene HurstImages: Courtesy of Roadshow Films