Published on Tuesday, 24 September 2013

 

MPC Mixes VFX & Brutal Action for ‘Assassins Creed IV’ Trailer

MPC worked with Stink director Adam Berg on a brutal, 90-second trailer for the launch of Assassins Creed IV, Black Flag. The film has been released in cinemas and on television, promoting the game to its fans around the world. Blending dramatic live action with 2D and 3D visual effects, the project involves impressive set builds including a ship built to scale and a 3,000 cubic metre water tank, plus a cast of some 100 stunt men.

Eyes Peeled

MPC’s team, led by VFX supervisor Franck Lambertz, planned carefully for the three day shoot and then completed the FX work over a four week schedule.  Led by Adam, their aim was to capture as much of the action in camera as possible and then integrate custom VFX. Franck said, “Adam understands VFX really well and wanted to create a gritty, realistic spot that keeps the authenticity of the game intact. The interaction of the live action footage between the CG and 2D environments is paramount in this film. We have a high level of detail taking place in both the foreground, mid-ground and in the distance as the camera pans up through the ship. The gamers know their stuff and will have their eyes peeled for any mistakes or incorrect details.”

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During pre-production, MPC created a full 3D pre-vis of the ship and the continuous camera move, which allowed Adam more freedom to direct the large cast on set. The opening scene of an eerie underwater environment was filmed in a tank, purpose-built on set.  The floating men were captured on five different plates, which the team then composited together before enhancing the scene with light effects, debris and bubbles. The hull of the boat, passing into view as the camera transitions upwards, was created in CG.

The remaining action scenes above water were achieved with a combination of in-camera action, along with integrated shot and 3D elements. The intensity of the action required separate plates, shot on green screen and on the set, which were then composited together. Matte paintings were used throughout for set extensions and boat environments, while the addition of CG fog and smoke elements give the impression that the camera is in the midst of the action.

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Visual references were provided to the artists of the exact game footage, which they followed very closely in order to achieve both the game authenticity and the realism Adam wanted. They used the same ships and style that are used for the game, as well as the Caribbean setting for the final, wide shot encompassing burning ships, palm trees and a cloud filled sky. They also looked to a lot of reference footage of game play, although Adam was looking for a more cinematographic feeling, which is closer to the MPC team’s background.

Fear and Sweat

“One of the key messages from Adam was his intention to keep the scene real, grungy even. The audience should feel the fear and the sweat.  We wanted to contribute to the atmosphere but not take it over,” said Franck.

“During the filming of the main action scenes, I was helping to ensure the shooting crew captured as much real action as possible in camera. Of course, only so much reality could be captured on the plate, so I was careful to flag when things were being filmed that could not reasonably be altered during the VFX process. The DP Mattias Montero, as always, did an amazing job of lighting despite the fact we were shooting against a huge green screen, and production designer David Lee managed to get the scale of the set exactly right.

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“Our role was to make the action epic and not drive it according to a technical decision.
The rotoscoping required was very precise - it took many hours to match the thousands of details on the main plate, element per element. We had a great deal of variation in lighting and atmosphere between each layer as well. The people in the foreground came from different plates. It was a bit like a sewing exercise. We populated the background boats with CG characters. It’s very hard to notice, but for the last shot, we pushed the work further by adding people on the beach.”

Camera Move Pre-viz

Franck and the team proposed to Adam the idea of building a pre-viz. It was important to have a precise idea of the timings before the shoot. They had numerous factors to consider – namely, to work out how long it would take to pass from 20m deep to the top of the mast. During the shoot, they used the pre-viz to start the motion control move, but it quickly became obvious that it needed to be adapted to both the set and the stunt action.

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“A pre-viz should always be more of a guide than an iron collar,” Franck remarked. “The major concept of this film was the continuous camera move. Without a pre-viz we would have had to fight against incorrect timing that would have been very difficult or impossible to fix. Although Mattias, the DP, was not on hand during the previz stage, we had discussions about what the move should look like and how we could avoid a CG move that a motion control could generate. We wanted the camera to be driven per the action, or close to it.”

Because the sets were elaborate and built to scale, Franck needed make sure the team had enough information about them in post. “It was an interesting process,” he said. “We started from a 3D model of the galleon for the previz. Very quickly we realized it would have to be adapted and revised to reduce the journey to the top of the mast. We cut out all the parts with minimal action.  Adam wanted the canon deck to be higher to let the stuntmen act without to being too uncomfortable.

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“We made our adjustments and then gave our model to the production design team, who then decided what they should and could build, and adjusted the model to their taste. I came back from the shoot with the final model they used to help with the build as well as all the survey detail I took during the pre-light.”

Lighting for Drama

The light effects were critical to the drama they wanted to create, and involved interactive lights, lights in the fog and smoke, underwater light effects, and fire light, from the distant background to up close to camera. “Lighting was used with caution to give as much depth to the shot without hacking the main foreground action, and it was lovely to find the balance between each element,” said Franck. “We had a couple of adjustments between each type of work -  matte painting,  CG boat and sea, live action -  to find a nice balance with the full composition.

“We actually added a lot of the atmosphere and interactive lights while on set. Mattias managed an interactive light rig, which was totally controllable by using a mixer. I don't really think it works to add too much of this in post.”

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MPC’s 3D team was led by 3D Supervisor Fabian Frank. “We always tried to get the best results by using a combination of different techniques,” he said. “For most of the effects close to camera like the water splashes, gunfire and most of the underwater sequence we relied mainly on 2D compositing with real elements. In some cases we enhanced the results with additional 3D renders. The explosion in the cannon deck obviously would have been too dangerous to shoot entirely in-camera. In addition, the ocean included dynamic fluid simulations around the shore and ships fighting were created completely from scratch.

Ocean Surface

“Besides the creation of the entire ocean surface, the shore and close up water, the fighting between the ships was our main focus. We spent a lot of time looking at reference footage of open water as well as interaction with ships and shores. The aim was to develop a setup that allowed us to generate realistic large-scale fluid simulations while keeping it fast and efficient in terms of data volume.”

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They found that Houdini was the perfect tool for this, although it was new to the team, as it gave them a lot of flexibly and freedom. VFX artist David Picarda handled this for the two long shots. Houdini was also used for the many wood-shattering explosions and 3D smoke simulations. The fire was either in camera or composited 2D real elements. The pipeline was based on Maya and mental ray, and compositing was done in Nuke.

“The atmospherics, including fog and smoke, played an important role in creating the look Adam Berg wanted to achieve, and in most cases it was also a composite of 2D and 3D elements,” Fabian said. “The majority of the dynamic and non dynamic smoke in the background was generated and rendered in Maya. Foreground 3D smoke such as the cannon smoke in the cannon deck has been simulated in Houdini and rendered in Mantra. For the atmospherics in the wide shot on top of the mast at the end of the film, we relied on the 2D matte painting.”  www.moving-picture.com