Research scientists from the Fraunhofer Institute for Telecommunications are optimizing the technologies that make it possible to watch TV in 3D without technical aids such as 3D glasses. A new four-camera system will even be able to handle live transmissions.
“The breakthrough for 3D television will only come when you don’t need glasses. Wearing them is just too uncomfortable and tiresome,” said Frederik Zilly from the Fraunhofer Institute for Telecommunications in Berlin. Research scientists are working with 12 partners in the MUSCADE project on technologies that will make it possible to watch 3D TV without glasses.
For this to happen, autostereoscopic displays are needed, which are coated with special optical foils. They create two different images for the left and right eye, which is the basic principle of 3D vision. To allow different viewing positions – for instance, when the viewer moves his head – these displays use five to ten different views of an image. In the future, this number will be considerably higher. As conventional stereo productions only have two views, the captured images have to be converted before transmission, with depth information extracted from them. In order to reliably determine depth information, more than the usual two cameras must be used. But it can take days to calibrate four cameras.
The researchers are working on a four-camera assistance system that will reduce this timeframe to about 30 to 60 minutes. But with four cameras, calibration is much more complicated. 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 achieve this, the researchers have developed a feature detector that recognizes identical objects in the image on all cameras. Using their position, the assistance system then calibrates the individual cameras to each other.
But even after calibration small inaccuracies remain. These occur if lenses with fixed focal lengths are used, which in most cases are subject to small fluctuations. Such residual faults can only be corrected electronically using a digital zoom. This last correction stage is carried out by the new assistance system in real time, enabling even live transmissions.
