Film FreeD For Virtual Production

by David Fox

The BBC's FreeD camera tracking system is now available to help create real-time virtual sets on film having been adapted by London facility, The Moving Picture Company to make it easier for film actors and directors to work on bluescreen stages.

"The heart of the system is a completely unobtrusive motion control system with no set up time," said Sean Schur, MPC's creative head of 3D. It uses lightweight boxes mounted on top of the camera, which contain a tiny camera and LEDs which light special circular barcode markers randomly fixed to the ceiling or lighting rig, allowing the system instantly identify exactly where it is - if it can see any four markers. It makes it easy for hand-held camera work to be perfectly tracked. It takes about a day to set up all the markers on set, and an hour or two to calibrate the system (which won't need to be done again).

The system also uses the BBC's highly reflective Truematte cloth, which only needs a single blue (or green) LED lighting ring fixed around the camera lens. "Truematte gives a perfect key, much better than conventional bluescreen," said Schur. Besides its existing grey cloth, the BBC has developed blue and green versions for Disney, which can be worn by puppeteers, giving an even key even in shaded parts such as under armpits. It showed these new variants for the first time at VFX 2000.

Users can composite low-resolution versions of the graphics live on the set, although this does require pre-visualisation work, which Schur said most productions now do for effects work anyway. Back at MPC, the data is used to create perfect high-resolution graphics for compositing into the digitised film. It can also feed data into a motion control rig to recreate a move for miniature work. "It saves time all round. There is no tedious operator work trying to retrieve motion data from plates or hours spent setting up motion control rigs. The system is designed to give as much freedom to the director as possible," he said.

He believes it will prove particularly useful where actors have to interact with graphic elements, whether sets, objects or creatures. It also allows directors check that eyelines are right. "It makes it much easier to see what works immediately. It's really helpful to actors. It's incredibly helpful to directors," he claimed. They also have glasses which camera operators can wear, to see what they should frame for.

In tests, they have shot at up to 60 frames per second with no problems, and they are now working with three big-budget live-action feature films currently being shot in the UK (he wouldn't say which, but the demo footage shown at VFX 2000 involved a Lara Croft-like character, and Tomb Raider has just started production [late 2000]).

The BBC itself makes more than 500 hours of virtual studio programming each year, mainly news, sports and science, with four of its main studios and nine regions permanently equipped with FreeD, and has already licensed a TV version of the system to Radamec, but this is not as highly developed as the BBC now uses in-house or for the MPC version. Although the individual items are available separately, MPC is selling it as a complete service.

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David Fox