A new 3D TV technology does away with the need for special glasses -and remains responsive enough to handle live transmissions.
So-called autostereoscopic displays use special optical foils to create two different images for the left and right eyes. To allow different viewing positions – for instance, when the viewer moves his head – they need up to ten different views of an image.
As conventional stereo productions only have two views, however, the captured images have to be converted before transmission, which means depth information needs to be extracted from them. To do this reliably, more than the usual two cameras are needed.
The new MUSCADE technology from the Fraunhofer Institute uses four - but this makes the already complex stereo production extremely intricate and expensive. "It can take days to calibrate four cameras to each other," says the Institute's Frederik Zilly.
But the team's now created a four-camera assistance system which will reduce this timeframe to as little as half an hour.
"The development is based on our STAN assistance system, which has already proved its value in conventional stereo productions. But with four cameras calibration is much more complicated," says Zilly.
This is because all positions and angles of the cameras must be set exactly the same so that the optical axes are parallel, all lenses have the same focal length and all focal points are on a common stereo basis.
To speed up the process, the scientists have developed a feature detector which recognizes identical objects in the image on all cameras. Using their position, the assistance system then calibrates the individual cameras to each other.
After calibration, small inaccuracies remain, which need to be corrected electronically, for example by using a digital zoom. This last correction stage can now be carried out by the new assistance system in real time – making even live transmissions possible.
The team's now working on an efficient video encoding system for compressing the huge volume of data from four cameras, so that the content can be transmitted over existing broadcasting infrastructure.