Computer Tracking System Revolutionizes Green Screens

One of the most challenging aspects of filmmaking is matching shots against green-screens, with backgrounds added in post-production. Now, Roomba co-creator Eliot Mack has devised a way to integrate the virtual backdrops seamlessly with scenes as they are shot.

Mack describes the process as "recreating the world on the fly", and that's pretty much exactly what his system, called Cinital, does. Although green-screens have been in use for decades, it is only now that directors can actually see what will essentially be the finished scene while they are still shooting it. Cameras outfitted with the Cinital system output all their movements, however slight, to a computer, which then instantly recalculates the position of the virtual background. This can eliminate a lot of the need for extensive post-production work in terms of compositing the actors with the backgrounds, as the director should be able to know in real time whether the shot is working.

This represents a rather astounding leap forward in green-screen technology, which had previously been rather worryingly dependent on manual approximation. Says the Massachusetts Institute of Technology's Slice of MIT blog:

To add backgrounds in post-production, technicians have to know exact camera positions and lens optical parameters used during filming. Currently, visual tracking involves 3,000-pound cranes fitted with rotary measuring devices that lack complete accuracy. Mack's invention puts Intersense optical-inertial and Airtrack inertial sensors onto the camera itself, which precisely record necessary data and eliminate the need to manually figure out tracking info.

Cinital has already been used on TV shows and movies such as V, Tim Burton's upcoming Alice in Wonderland adaptation, and the Knight Rider TV-movie. You can see a video detailing Mack's invention below:


[Slice of MIT]