• CGSociety :: Production Focus
    7 October 2010, by Renee Dunlop


    Double Negative (DNeg) was the sole FX vendor on Inception, with some miniature work from New Deal Studios. Dneg delivered some 500 FX shots for the film with a team of up to 275 people through various phases of production. Shot on film, often with a hand held camera, the medium was the least of Franklin's worries. Fortunately, DNeg is the veteran of numerous hand-held shows starting with Enemy at the Gates way back in 2001.

    "For that show we pushed our tracking as hard as we could," said Franklin "establishing a standard that became the basis for our work over the following decade. Perhaps the most extreme examples of hand-held technique would be The Bourne Ultimatum and Green Zone, both directed by Paul Greengrass. The camera movement in Inception was fairly mild by comparison!"

    Double Negative built a comprehensive film color pipeline to handle the work on Batman Begins. That was used again on The Dark Knight and then on Inception, "with a few tweaks that we've added over the years." Dneg is an established FX house with years of history, and when the company was first launched, all movies were shot on film and then graded in the lab as opposed to a DI suite.

    "In essence," explains Franklin "it's not really that different to working with a DI - the difference is that you are setting your own grading numbers based on the film clips supplied by the production as opposed to a grading suite being run offsite. It must be said that Chris's films are the only large-scale productions that we work on that don't use the DI process." Note: 'DI' is Digital Intermediate, the more complex digital version of the telecine and color grading process.



    As the idea of VFX post production evolves into the more efficient preproduction method, the preproduction process is gradually being embraced by certain filmmakers and DP's (Director of Photography, also referred to as DOP's). Previous experience from working with Nolan made DNeg aware they needed to brace themselves early for what was to come, and to be as prepared as possible from the onset. Franklin, whose previous work with Nolan has earned him a strong level of trust and respect, was granted permission to read the first draft of the script under very tight security. That early exposure to the FX requirements in the film helped Franklin prepare for the pre-production and on set decisions he needed to make. Nolan also uses previs, but not as often as some other directors, and he tends to use it to aid in his design decisions rather than for technical ones such as camera angles or editing. Nolan will define the more intimate decisions during single shots and multiple actions.

    Still, the post production schedule was a bit of a marathon, with shots needing to be completed in about four and a half months. And to meet early temp screenings of the film, Nolan wanted shots that were close to finished within the first six weeks of the post schedule. In order to meet the initial six week temp shot deadline, it was imperative to build the assets in advance and make sure the production pipeline was flowing smoothly.


    As Ariadne (Ellen Page) gains confidence and establishes control over the dreamscape she begins to experiment with the structure of the landscape.

    In the process of exploring her newly found skills, she folds the streets of Paris into a giant cube, twisting architecture and physics into an impossible shape.

    Luckily, due to Franklin's reading the early draft, he knew that Nolan had already scripted the 'cube city' moment in the first draft of Inception, describing the scenes of Cobb (Leonardo DiCaprio) and Ariadne walking on the inverted planes of the folded streets.

    Production Designer Guy Dyas's Art Department had supplied early concepts of the end result, but there was no indication of how it Paris would transform from a normal cityscape to one whose horizon would lift up and fold overhead. "One of the great things about working on Inception was the fact that it was my third picture with Chris, which meant that we were able to draw on things we had both seen together.

    When thinking about how we might go about folding up the city, we recalled how, on Batman Begins, we had watched the raising of the drawbridges over the Chicago River and how, from certain angles, it looked as if the entire street was lifting up, complete with sidewalks and street lamps.

    This then became the basis for how we would fold the street- a series of hinged sections, raising up and arcing over Cobb and Ariadne as they watch from below."

    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.
    Alison Wortman came up with the previs of the folding city that was a strong enough design to carry through to final production. It was a tough challenge. For example. as the street surface folded upwards and over, intersecting of buildings were hidden through a series of cheats that would hide those areas either behind other geometry or through timely camera moves.

    Lighting had to be cheated too, as the sky was blocked by geometry, while still appearing believable. To a point, the folding building's own cast shadows were used as other lighting was brought into play during the folding process. Initially the sequence was one long shot of roughly 1,000 frames before editing chopped it up, so during that initial long shot, cheats had to be developed to work smoothly and without distractions.


    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.
    Despite the surreal nature of the concept the city needed to look absolutely photorealistic. The cityscape of Paris, with it's ornate buildings and daylight lighting was one of the more difficult architectural challenges Dneg has tackled to date. The detail of each block is unique, and everything had to be completely believable to visually tie in to the extreme detail captured on film.

    Several weeks before the scenes were shot on location in Paris the VFX team conducted a detailed survey of the four-block section of Paris. Lidar VFX Services provided millimetre-accurate scans of the buildings and DNeg's artists took countless thousands of high-resolution stills. These were then used as the basis for a set of detailed digital models that were used to replace the real buildings in the plates shot by Inception DP Wally Pfister.

    The animation of the street came from an early previs that Dneg created. "Chris liked the shot so much that he designed a sequence around it and used my laptop - loaded with a QuickTime of the previs - to cue Leo and Ellen on location in Paris so that they were looking in the right direction at the right time." The CG architecture had to stand up to full screen scrutiny in scenes such as where Page and DiCaprio walk up the wall, where the entire environment is full screen CG.

    Dneg's shading and lighting pipeline was updated to make use of the new Ptex texture-mapping technique that allowed the CG team to circumvent the usual UV-coordinate mapping stage, enabling them to concentrate on getting the textures absolutely perfect.

    Detailed animations of CG pedestrians and traffic were added to complete the shot, and any time something is seen that isn't standing on a horizontal plane, it's CG.

    © Warner Bros. Entertainment. Image courtesy Double Negative.

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    The collapse of the snow fortress was created through a combination of several different techniques. The Special Effects Department, supervised by Chris Corbould, rigged the full-size fortress set, built on location at the top of a Canadian mountain, with a large amount of dynamite to start the destruction in spectacular style.

    The destruction of the set was shot from multiple angles, and the Dneg's VFX team added additional layers of CG debris to enhance the force of the pyrotechnic blasts.

    For the wide angles of the collapsing structure, New Deal Studios in Marina Del Rey, California, created a sixth scale miniature of the base which was rigged with pyrotechnic charges to match the timings of Dnegs' previs. The finished model was nearly 40 feet high and the collapse was filmed with VistaVision cameras running at high frame rates in order to give the illusion of the required scale.

    DNeg added the surrounding alpine landscape and extended the structure of the miniature to complete the base. Dnegs' proprietary Dynamite rigid body system and their Squirt fluid dynamics toolset were used in conjunction with Houdini to create additional destruction, completing the demolition of the massive base.

    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.


    The scenes of Arthur (Joseph Gordon-Levitt) fighting with the security guard across the walls, ceilings and floors of the hotel dreamscape were entirely practical. No rig removal, digital double work or set extension was needed.

    However, the zero gravity scenes were a different deal entirely, requiring extensive rig removal and digital recreation of the sets to complete the shots.

    The shots inside the elevator were achieved through primarily practical methods. Dneg supplied previs of the sequence which helped the Special Effects and Stunt Departments work out the required rigging and technical setups. Dneg then removed any wires to complete the illusion of zero gravity within the elevator.

    © Warner Bros. Entertainment. Image courtesy Double Negative.

    By building a set that was set on it's end and hanging the actors to move towards the camera with the wires hidden behind them, it helped to facilitate the task of digital wire removal later. In the bedroom scene when the actors are bundled together by Gordon-Levitt, the door he walks them through is actually located above them and they are being pulled up through it while they remained motionless, clothes and even shoelaces stiffened so as not to give away their actual angle. This was an extremely complicated scene to cleanup and reconstruct. The various background elements had holes cut to allow for wires and rigging had to be completely hidden, and some face replacements for the stunt actors had to be tracked in, using cyber scans and head scans of the actors, shot while they were filming the hotel interiors in England. A huge, 300 foot long set was used for the scenes looking down the elevator shaft. Dneg added set extensions to further enhance the illusion.


    As for the train, "Chris was very keen that the dreamscapes should feel completely real and whenever possible he tried to shoot as much reality as he could. We discussed the possibility of a digital train, but the level of interaction that Chris wanted to achieve would always look best if it was created practically- and I think everyone would agree that the result is spectacular," said Franklin.

    VFX work in the shots involved the removal of the multiple cameras on the location and the addition of torn-up asphalt as the train rips through the street surface.

    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.


    © Warner Bros. Entertainment. Image courtesy Double Negative.

    © Warner Bros. Entertainment. Image courtesy Double Negative.

    © Warner Bros. Entertainment. Image courtesy Double Negative.


    As the city implodes on itself, a psychological manifestation of DiCaprio's mental interpretation of his deteriorating mental state, large chunks slide off into the sea like sheets of ice sliding from a glacier. Since the cityscape did not need to be recognizable as a specific location, it allowed Limbo to be built procedurally.
    Dneg started with a basic polygonal model for the glacier, then designed an algorithm to populate the mesh with simple architecture that coincided with the varying heights of the glacier geometry. Then more rules were added to flesh out detail like street blocks that coincided with the glacier and architectural size and locations. After building layer upon layer of architectural detail, over a period of several months, the team restructured their pipeline to handle the amount of data.


    © Warner Bros. Entertainment. Image courtesy Double Negative.

    The result was a crumbling city emerging from a jagged cliff wall that reassembled the war torn cities they sourced in their research and was completely realistic even in it's nightmarish dream state that brought the film to a climax and tantalizing ending. Just as Nolan wanted it, proving dreams really do come true.
    Inception
    Double Negative
    Paul Franklin, VFX Supervisor
    Alison Wortman, Previs, Dneg
    Guy Dyas, Production Designer
    Chris Corbould, Special Effects
    Wally Pfister, Director of Photography
    New Deal Studios
    Houdini
    Lidar VFX Services
    Ptex
    Writer: Renee Dunlop

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