Piero went to air for the
first time during BBC's Match of the Day, on Saturday 25th September
2004, and has subsequently also been used for other sports, for example
during the RBS Six Nations Rugby Championship in 2005. An HD version
was used for the first time in the BBC's World Cup coverage in 2006.
Red Bee have also sold systems to Sky Italia, TV Globo (Brazil) and
Hong Kong i-Cable.
The system initially relied on a camera head equipped
with sensors to measure the pan, tilt and zoom of the camera and lens. BBC
Outside Broadcasts developed methods to relay this data back to
the studio or Outside Broadcast vehicle along with the accompanying
video. The
video and data may then either be recorded for later processing or
fed directly into a PC for processing live.
As a part of our work in the MATRIS project,
we developed a method to measure the camera position, orientation, and
field-of-view in real-time, by tracking lines on the pitch. As long as
at least three line or curve segments are visible in the image, the camera
pose can be computed. The method was subsequently incorporated into the
Piero system, and was first used on-air on 10th September 2005. This
image-based camera tracking method is now used for majority of Piero
graphics. It has also been licensed to RT Software Ltd
and is used in their Tog Sports system.
The whole system (including camera tracking and graphics generation)
runs on a single PC.
The operator has a console with a graphical user interface, which provides
the ability to control video footage and review incidents from new camera
angles. The operator can try different animated camera moves, apply graphic
treatments and record them for broadcast as appropriate.
In order to generate a virtual view of the action, the
players are segmented from the pitch using a chroma-key
technique, and the 3D location of each player is computed using an
assumption based on height, for example that the bottom part of the
keyed region (usually the feet) is in contact with the ground plane.
The video image of each player is then mapped onto a plane at the corresponding
3D position, with a transparency determined by the chroma-key output.
A virtual stadium model is also added, before rendering the scene from
the chosen viewpoint.
The software is written in Java and C++, using the OpenGL
API on the Linux operating system. The hardware is a standard PC and
graphics card and an SDI video I/O card.
Several current projects at BBC R&D may provide future
enhancements to Piero. For example, our work on virtual
view generation from multiple cameras in the
iview project will extend the range of virtual
camera movement that is possible, and give improved results in areas
of occlusion.
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iview
