The main reason given in consumer research on the subject is the need to wear special glasses when viewing 3D TV. While some find wearing the glasses uncomfortable, there is the added issue of expense when it comes to the kind of 3D technology currently marketed at the home. At the moment, many domestic 3D TV sets require the use of 'active shutter' glasses, the cost of which can quickly add up if you want to be able to watch programmes together as a group.
The development of passive 3D TV - which requires only cheaper, 'passive' glasses to be worn - is being pushed as a solution to the cost issues of active shutter glasses, but the fact remains that special specs still have to be worn. While this can be a bit of an annoyance to those with good sight, it can be more of an issue to those that need to wear glasses to watch TV. This seemingly trivial issue has in fact been identified by industry analysts as the primary factor that will stop the mainstream uptake of 3D TV, which has lead to an increasing emphasis on developing 3D TV that can work without glasses.
The technical term for delivering this effect is autostereoscopy. There are several possible technological approaches that can achieve this glasses-free 3D effect, but at the moment each works by playing with the binocular vision of the eyes. Put simply, each eye needs to receive a slightly different image for the brain to be tricked into 'seeing' a 3D image displayed on a screen that is effectively 2D, or in other words, flat.
The two main methods developed so far are called parallax barrier and lenticular technology. Parallax barrier replaces the filtering function carried out by special 3D glasses through the use of slits at the front of the screen, which ensure that right and left eye pick up different images. The problem with this solution is that the viewer needs to sit in a fixed position. Lenticular technology uses screens similar to the ridged rulers you will have seen at school, where the images appear to move when the ruler is tilted. At the moment, the cost of producing lenticular screens is prohibitive. All in all, you can rest assured that your HDTV will not be obsolete for some time! For more information on the future of 3D TV, try looking at: http://www.lgblog.co.uk/2010/06/a-3d-future-without-glasses/.