When you go to see a 3D movie at the cinema you pay your premium, put on your funny glasses and sit back to enjoy it without really wondering how the whole effect is created until afterwards. But now the first wave of 3D TVs are arriving to bring a whole new depth to home entertainment and 3D technology could move from being an occasional spectacle to a common part of everyday life.
There are two main types of 3D TV technology on the market today, although both are based on digital techniques and both require the wearing of glasses in order to create the effect. To produce the illusion that an image on a flat surface possesses three dimensional depth it is necessary to show the left eye one image and the right eye a slightly different one, mimicking the manner in which we perceive depth in the real three dimensional space which we occupy. To shoot live action footage in 3D it is necessary to have two cameras mounted side by side and then to display the resultant footage using one of the two following techniques.
The first 3D TV technology produces the 3D effect by polarising the images for the left and right eye and then using passive glasses with lenses that blot out the appropriate polarised image so that the left eye sees only the left image and vice versa. This means that the glasses can be very cheaply produced and the ones you use in the cinema are essentially based on the same principle. The consumer market is largely devoid of this type of 3D TV, with these reserved for use on commercial premises such as in pubs, where having cheap, easily replaceable glasses is a boon.
The second 3D TV technology uses something called alternate frame sequencing. This is slightly more complex, but the result is arguably more pleasing and consistent. Here the viewer wears active shutter glasses which are synchronised to the television. When the image for the left eye is displayed, the glasses are instructed to close the lens on the right eye in a fraction of a second and so forth. Because of this the content is displayed at twice the frame rate of standard content, requiring that active frame sequencing 3D TVs have minimum refresh rates of at least 120Hz to keep up with the pace. Without proper synchronisation this system falls apart. The glasses are expensive and it may be necessary to purchase a separate synchronisation attachment for a television even if it is rated as 3D-ready, because only the top of the line models possess integrated synchronisation devices.
The major problem with the two current 3D TV technologies is that they both require each and every viewer to wear a set of glasses, often over their own prescription pair, in order to produce the effect. This makes 3D TV ownership even more costly than it already is. Electronics firms are already developing glasses-free 3D display technologies and the first widely available example of such capabilities will arrive when games console manufacturer Nintendo launches the 3DS handheld in 2011. The main limitation of glasses-free 3D is that the viewer must be in a particular position to experience the effect, which is fine for a single user handheld console, but more problematic for the TV market and development and innovation is ongoing.