November 2009: Bamzooki is a popular CBBC childrens television series that mixes a real studio environment with virtual creatures, created by the contestants. Now in its fourth series, Bamzooki Street Rules takes the safe studio environment to a new level of realism and scale, with the Zooks racing outside and inside across exciting new games.

Presented by Barney Harwood and Gemma Hunt, the show involves four teams of three contestants, competing with their zooks in a variety of live interactive contests. The outside location and stage are linked by a lift, opening onto different floors of a building, each floor having a different contest, eliminating teams until a winner is crowned.

From series one, BBC Studios and Post Production has provided tracking and keying expertise to the production team, to enable them to create the virtual elements within the real world. BBC Studios and Post Production’s Technology Development Manager Danny Popkin and his team have vast experience in virtual tracking systems. They pioneered the technology when it was first available and can advise and provide consultancy to programmes looking for innovative solutions.

To create the illusion on Bamzooki Street Rules, it is necessary to accurately link the camera positioning to the computer rendering the images of the games. There are a multitude of camera tracking systems available on the market, but most are really designed for virtual sets rather than virtual elements. Having an object sat on a floor in a precise position makes the calibration between real world and virtual difficult, especially with lens distortion affecting the real image size. In order to render the game in real time the computer cannot currently distort the image, and so assumes a perfect lens, which means that the images can slip in relation with each other.

Previous series were recorded at BBC Studios and Post Production’s Elstree Studio D using the Vinten Radamec free-d system, but with the change of venue to Pinewood it was necessary to design a new tracking method. After various test shoots both at BBC Television Centre and on location it was decided that sensor based pedestals provided a good and reliable solution.

The Vinten Radamec Quattro SE tracking pedestal is based on the small base studio Quattro with a 250E head and lens sensors. It proved to be accurate enough to cope with a fast moving game and provided very stable tracking data in the same message format as free-d, which was essential as there was not enough time to rewrite the computer program to use a different tracking system. Three pedestals were hired for the series along with external lens sensors, which proved invaluable as the lenses were changed after one day of rehearsal for tighter ones.

Although requiring a home position to set the 0,0 point to match real and virtual worlds, sensor based systems have no drift or jitter even when zoomed in on the tightest lenses. Some wheel slip can occur depending on the operators style of working using the steering ring or if the floor is not clean, however this is obvious and can be corrected easily and quickly by a ‘re-home’ which with practice takes less than 30 seconds. Being standard pedestals the camera operators were ‘at home’ straight away, and were able to deliver complex tracking shots without worrying about any tracking limitations.

Series Producer Rupert Harris says: “We were delighted with the impact of the mixed reality set which provided us with a dramatic and dynamic stage for all the zook action. We took a huge number of technical and creative risks over the course of the project but the talent of the technical team and their wealth of experience from the three series gave us complete confidence that our ambitious plans could be realised.”

He continues: “Unlike the previous three series which had elected to keep the virtual set to a minimum to preserve the mixed reality feel, we decided to go for a much bigger CGI game space for the fourth series, with giant boulders rolling down ramps high above the contestants heads to really immerse the viewers in the Bamzooki experience. Furthermore we wanted as much of the game-play as possible to be live and interactive. Creative decisions like these reduced the margin for error with the camera tracking system and virtual renderers significantly. But we succeeded in completing an extremely tight filming schedule on time and on budget and are thrilled with the outcome.”

Series Four - Bamzooki Street Rules started transmission on BBC One in November 2009 and continues through to February 2010.

For further information, please contact:
Georgie Hollett, Head of Communications, BBC Studios and Post Production
Tel: +44 (0)20 8624 9495
Mobile : +44 (0) 783484 5612
Email : georgie.hollett@bbc.co.uk

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