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3DTV: From Stadium To Living Room

On Wednesday, 19th May 2010, Nine Network Australia and SBS Corporation began the first free-to-air 3D television broadcast in the world. We take a look at the technology involved in getting 3DTV live from the sports field to your home.

By Nicholas Vinen

Australia’s Channel Nine and SBS (Special Broadcasting Service) are collaborating to broadcast live, in high-definition 3D, the three State of Origin rugby league matches (produced by Nine) and 15 World Cup soccer games (produced by FIFA) between May 26 and July 12 this year. This has been timed to coincide with the recent Australian consumer launch of 3D-capable high-definition television sets.

These broadcasts are possible due to a two month experimental broadcast license covering transmitters in Sydney (Gore Hill), Melbourne (Mt Dandenong), Brisbane (Mt Coot-Tha), Adelaide (Mt Lofty), Perth (Bickley), Newcastle (Cooks Hill & Charlestown) and Wollongong (Knights Hill). These broadcasts are made on a variety of channels but in all cases the trial is available on digital channel 40.

Some areas will unfortunately be left out due to the limited number and range of the transmitters being used for the trial. One of the purposes of the trial is to assess consumer interest when major live sports events are made available.

Making such broadcasts involves new technology virtually every step along the way – from the cameras at the game, to the processing and broadcasting equipment at Channel Nine’s headquarters and ending with the reception and display of 3DTV in viewers’ homes.

To assist with these new challenges at the production end, a technical team was brought in from California. The Burbank-based company “3ality” (pronounced “three-ality”) have provided 3DTV production equipment and a great deal of expertise, putting the Channel Nine team on a crash-course in 3D television recording and production.

3D cameras

We have already covered 3D camera technology extensively in “3D TV Is Here At Last!” (April 2010) and “Breakthrough Aussie Innovation: Making 3D Movies” (June 2010). 3D cameras for TV broadcasting are similar in concept to those used in shooting movies. The only real difference is in the image resolution – movies are shown on larger screens and demand more pixels, even compared with Full HD (1920x1080 at 50/60Hz, known as 1080p).

However, for the State of Origin rugby league match on the May 26, one innovative camera made its appearance: a wireless, hand-held, broadcast quality 3D rig and there are only a handful in existence. It consists of a pair of “lipstick” cameras mounted side-by-side to simulate the interocular distance and gives viewers the impression that they are standing on the sidelines, either looking at the match itself or else at the players on the bench.

Because the experience of watching 3D sport is so different from what we are used to, the camera work is tailored to suit the experience. The 3ality team have trained the camera crews in new techniques optimised for 3D sport coverage.

Viewers watching the games in 3D will notice fewer cuts and zooms than we are used to on regular TV. There are also fewer close-ups. This is because with 3D TV, it is much easier to follow the action with a wider perspective. The players and the ball are very well defined on the screen and since our brains are already wired to decode depth information, following the action is intuitive.

As a result, wider, longer shots tend to be used which are better able to show the action within a larger context. In fact, watching sport on 3DTV is much more akin to being at the game than is a regular TV broadcast.

However, this isn’t the only reason for changing the shooting technique. The other reason is that rapid cuts and zooms can be very jarring when viewed in 3D, especially if the convergence distance changes dramatically between shots.

Therefore, every 3D camera has an additional operator whose sole job is to control the convergence distance for that camera. This is managed by a new production position, a “stereographer”, who is in charge of ensuring that cuts between cameras are only made at the point when their convergence is close enough to avoid a jarring transition.

Camera convergence can be adjusted mechanically but 3ality’s system also involves digital processing for finer control. It is even possible to adjust convergence with digital processing only (eg, with a Sony MPE-200 Stereo Processor) but a combined approach is best.

3ality have developed rigs using two different mechanical systems. One solution is to mount the cameras side-by-side with one fixed and the other moving closer to or further from it (while automatically adjusting zoom and focus).

The other method involves beam-splitting using a piece of precision semi-mirrored glass similar to that used in telescopes. In this case the right camera is mounted horizontally and the left camera vertically. Beam-splitting rigs can simulate much smaller interocular distances (virtually down to zero) so they work much better in scenes with objects close to the camera.

Click for larger image
Nine NRL SOO1 On-Air Production Gallery, taken at the first State-Of-Origin match held in Sydney on May 26. Each of the monitors depicts the live individual camera output, with the Director "calling the shots" as required.

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