Issue: Volume: 27 Issue: 1 (Jan 2004)

Tools for Tracking


At the time, Brickyard was looking to land a television commercial for Volkswagen that featured one continuous shot in which the camera makes a 360-degree circle around the featured car. The problem was that that shot had been taken the year before, and the current model of the car had different wheel rims. As a result, Volkswagen was considering scrapping the commercial altogether unless Brickyard could find a way to doctor the shot to seamlessly insert CG models of the new rims onto the car.

Even though Brickyard regularly uses Discreet's flame and combustion to perform all kinds of visual magic, Drewes admits that performing this particular trick would be nearly impossible to pull off using their existing camera-tracking capabilities.

Eager to find a solution and win the job, the staff decided to place a call to Oxford, England-based 2d3, which, they'd heard, had a powerful 3D camera-tracking program called boujou. "We told them we have this scene and we'd like to see if they could track it," recalls Drewes. "We told them that if they could get the track and we got this job, we were going to buy boujou. They tracked it very quickly and sent it to us, and we were very happy with the results. The track was perfect. And that one job paid for the cost of the software."
Brickyard VFX relied on boujou to create a long pull-out shot for a joint Volkswagen Beetle/Apple iPod commercial. The software helped Brickyard create a seamless shot in which the camera moves from a close-up of the iPod to a view of the car from high ab




Since then, Brickyard has used boujou on several occasions, most recently for another Volkswagen commercial promoting a cross-marketing campaign with Apple. This commercial featured another continuous camera movement that started with a close-up shot of an Apple iPod located inside a Volkswagen Beetle, and then rose skyward through the car's sunroof. Although it might look simple, it proved to be a complex shot that required the use of numerous composites and boujou's camera-tracking capabilities. "Without boujou," says Drewes, "we would have had to spend a lot more time tracking by hand."

While an increasing number of compositing programs are beginning to offer motion-tracking functionality, including such low-cost applications as Adobe After Effects, these capabilities tend to be limited to point trackers, which are useful for tracking 2D objects in a scene. Yet, 3D camera trackers offer significantly more sophisticated capabilities due to their ability to track objects and camera moves in 3D space.

"Point trackers have no knowledge of the camera, so they cannot help you when the object you are tracking goes out of a shot or behind something else in the scene," explains Chris Steele, CEO of 2d3. "Because boujou builds a knowledge of where things are in 3D and the way the camera moves, it knows where things are and how they are moving in 3D."

Whether the job requires adding CG rims to live video footage of a car or adding a virtual character to a battle scene in a movie, camera-tracking software can ease the task significantly. "The technique is used a great deal for extending sets or for ensuring that shots have correct historical detail," notes Steele. "Often it is used for adding props that were not constructed in reality."
Pixel Magic uses RealViz MatchMover Professional for a variety of visual effects shots. At left, the software is checking the 3D coordinates of CG objects inserted in a scene in DareDevil, in which the title character balances on the ledge of a bui




Only a handful of vendors specialize in 3D camera-tracking software, and 2d3 is one of the market leaders. Its long list of customers includes such effects houses as Dreamworks, The Orphanage, Ring of Fire, and The Moving Picture Company. According to Steele, boujou's competitive advantage is that it is built upon an architecture specifically designed for automatic processing.

While 2d3 points proudly to boujou's automated features, another leading player in this market takes a different stance. Like 2d3, RealViz also hails from Europe, specifically from Sophia Antipolis, France. Its offering in this market is MatchMover Professional 3.0. And if there's one thing the company's most proud of, it's the software's ability to handle complex tracking problems through its manual controls.

Jason Baker, motion tracker at Framestore CFC, a London-based effects facility, relied heavily on MatchMover to create scenes in the recently released movie Underworld, which featured humans transforming into werewolves and vampires. "A number of other matchmoving packages are available, each with its own strengths and weaknesses," he says. "MatchMover's strength is in providing the user complete control over every aspect of the tracking process.

"I tend to use MatchMover for shots that require a lot of manual intervention, in other words shots that cannot be easily tracked automatically," Baker adds. "These include shots that are very motion-blurred or have a lot of objects or people obscuring the features you wish to track. I also would use it if I was provided with a very accurate set of survey data (scans and marker positions). This additional information can be entered easily into MatchMover to give a much more accurate solve."

Rounding out Europe's monopoly on the camera-tracking business is Science-D-Visions, which hails from Dortmund, Germany. A pioneer in the market, the company offers 3D-Equalizer (3D-E), which has been around since 1996 and was awarded a Technical Achievement Award in 2001 from the Academy of Motion Pictures Arts and Sciences for its contribution to "surveyless tracking."

Used extensively in feature filmmaking, 3D-E has played an important role in the making of various movies, ranging from The Phantom Menace and Gladiator to Spiderman and Lord of the Rings.

Matt Mueller, the senior camera technical director for Weta Digital, the New Zealand-based effects facility that has been dazzling the world with its work on the Lord of the Rings trilogy, is among those who speak highly of 3D-E. "Our camera department relied heavily on 3D-Equalizer for complex camera solutions and object tracking for over 500 shots on The Two Towers," he says. "3D-Equalizer's speed, flexibility, survey import, and new auto-tracking features made difficult shots manageable. 3D-E addressed all of our needs while in production and enabled us to complete work which would not have been possible with other software."

With glowing comments like this coming from the users of all three leading camera-tracking programs, it may take some time and testing to determine which program will best meet users' particular needs. But they can take comfort in knowing that the once-arduous task of marrying computer graphics to live film or video footage has become considerably easier.

Stephen Porter is a contributing editor of Computer Graphics World and a freelance writer who covers video, graphics, and digital content creation technologies. He can be reached at sporter@gsinet.net.



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