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| New York’s Stitch opened an insert stage earlier this year. |
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In fact, many have found the matchmoving process somewhat daunting. Director Robert Rodreguez actually resorted to building a motion capture stage around his set and putting motion capture markers on his camera in order to track his camera moves for some of the greenscreen shots in Spy Kids 2 (see Film & Video, 8/02, p.19). It is a technique that Peter Jackson also experimented with on the The Lord of the Rings: Fellowship of the Ring.
"With motion control, you really want to pick and choose your battles," said Gray Marshall, cofounder and creative director of Venice, Calif.-based Gray Matter FX. "One of the big problems is that production is often scared of motion control, so one of the challenges for the visual effects artists and supervisors is to educate them that this is the right way to solve their problems and show them that it doesn’t necessarily have to be a pain."
To that end, Marshall is a big fan of the smaller repeatable, pan tilt heads from companies like Aerocrane. "There has been consolidation in the motion control industry. At the same time, there are an emerging group of systems that are being touted as repeating heads. They don’t have all the flexibility of programming that a motion control system would have, therefore they don’t fully replace motion control. But they are operated by the regular camera crew. They are lightweight and ideal for this kind of pan-and-tilt, capture-it-and-play-it-again, kind of thing," he explained. "So it gets the visual effects team what they need in terms of imagery and control, and it also gives production the feeling that there isn’t this alien machine invading their set, and that seems very important to them."
Marshall, who started his career as a motion control cameraman and offers his expertise in motion control for feature film work, (among other services provided by Gray Matter), reported that motion control cameramen have a lot in common with animators.
"The difference between motion control and computer graphics is basically what your end curve ends up doing. They are really points along a spectrum," said Marshall. "You are still manipulating curves and animating —manipulating a camera in the case of motion control — but your basic tools that you are working with on a computer screen to define motion, to define timing and control, they are the same tools you are going to use in any animation program like Maya. They’re really the same skill sets.
"Motion control is traditionally used to do multiple passes over the same scene, shoot miniatures that match to live action plates, and create live plates for CG compositing. This is where some of the new software packages for motion tracking fit into the puzzle with their ability to extrapolate the camera’s position from the footage itself. Packages like 2d3’s Boujou and Realviz’s MatchMover, as well as built in trackers in animation packages, use complex algorithms to extrapolate the camera’s position in 3D space by analyzing 2D footage. Imagineer Systems, developers of Mokey, software for wire and rig removal, is in development on a similar tracking package.
That data can then be fed into an animation package like XSI, Maya or 3ds max to drive a virtual camera.
At Siggraph, Realviz unveiled its MatchMover 2.5 Professional, a new version of its tracking package which added new features like a matte drawing tool, enabling users to specify areas for exclusion from the tracking process; improved performance with low contrast or motion-blurred footage; new camera constraints; support for anamorphic lenses, and new export formats including discreet’s flint/flame/inferno and Apple’s Shake.
2d3 meanwhile was showing version 2 of Boujou which added features for precision intervention, which allow the user to guide the process for difficult shots, as well as workflow enhancements to help studios integrate Boujou into their existing tracking methodologies, and a re-engineered tracking engine to handle more difficult shots.
"Motion tracking is most useful when you take a live plate that has been shot and then figure out in post, using tracking software, what it is that happened. And that data can go several places. That data can then be used to create a 3D model. It can then be used to create a digital background, that will be used in conjunction with the plate for replacing pieces of it, or it can also be then handed to a motion control stage to shoot a miniature that will be added to the scenes," explained Marshall.
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