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Mar 28

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3/28/2011 9:19 AM  RssIcon


James Doddington is Chief Technical Officer for Three Media Associates.

Following the success of movies such as Avatar and Toy Story 3 there is a movement to bring stereoscopic 3D to television. There are now channels dedicated to 3D, but while many of the technical issues have already been addressed, there is still a long way to go before it can be regarded as a practical proposition.

A search through the scientific journals found more than 240 papers and commentaries on 3D, many of them based on work completed as part of military simulation systems. They suggest that, for a significant part of the audience, there are intractable challenges.

It is well known that a significant part of the audience simply cannot appreciate stereo 3D content, either because of deficiencies in one eye or because their brains struggle to process it. A further 10-15% of the audience will have distinct physiological symptoms as a result of watching 3D, most typically headaches, which can progress to migraines.

About 10% of the audience can be expected to have symptoms similar to motion sickness. This is thought to be because of the conflict between vergence – the angle between the eyes, which is what gives stereoscopic 3D imagery its sense of depth – and accommodation, the change of focus point of the eyes, which varies in real life but not when all the images are on the plane of the screen.

Even more seriously, there is anecdotal evidence – from respected sources, but not scientifically proven – that this disorientation can lead to the triggering of schizophrenia, and even to the development of mental disorders wherein one were previously diagnosed. This is thought to be because the illusion of depth creates a conflict in the perception of what is ‘real’. That is likely to be a bigger issue in the home than in the cinema where there is nowhere to look but at the screen.

If given these concerns , you want to pursue stereoscopic 3D television, how can you do it as well as possible?

Comments so far have focused chiefly on the pictures, and rules such as no fast cuts, no crossing the line, and no big zooms are well known. What is less frequently commented upon is the importance of audio.

SMPTE research attempted to quantify its importance and suggested that, “44-48% of the viewing experience was enhanced by the audio”. Given that the 3D illusion is fragile anyway, it makes sense to use any hooks you can get, and the accurate placement of sounds to match the visual elements is one additional tool.

The challenge is that, even with good attention to detail in 5.1 or even better, surround sound, the producer has no control over what happens in the home. Users may not set up a home cinema correctly, or sit in the ideal spot every time, and for broadcast television they may not even turn on the system at all, relying on the integral (stereo) speakers in the television set.

In terms of the television set, there is a real risk of a standards war that could hinder the prospects of 3D in the home. Consumer electronics manufacturers are faced with either the choice of sequential frame displays (which can be added to modern televisions for virtually no cost but to be viewed with expensive active glasses) or polarized displays that add an additional $1k to the manufacturing cost, but which use glasses an order of magnitude less expensive. Auto stereoscopy is a long way off at the moment.

The solution most choose is sequential frame displays with often none, or at most two pairs of active glasses, with the box. If each manufacturer uses a different protocol for synchronization that means you cannot take your glasses to watch a friend’s television. Looking at it the other way, inviting a few friends around to watch the big match might involve you buying US$100 of beer and US$1,000 of new 3D glasses. And of those eight friends, one is likely to have a migraine and one motion sickness…

In conclusion, then, stereoscopic 3D television in the home is inevitably an illusion that will be hard to maintain. The screen is not completely immersive so there will be real world 3D objects in the visual field that will stress image processing in the brain. Good, accurately placed audio helps to a very large degree, but this is hard to do in production and even then there is no control over its reproduction in the home.

There are medical issues, as well as the purely optical ones with viewers who cannot see the illusion at all. And there are social disadvantages: many people do not feel comfortable with the idea of wearing ‘geek’ glasses in the home. If you tune in to a 3D channel everyone has to wear the glasses, whether they want to or not.

Finally, there is the question of cost. CE manufacturers have an interest in making 3D the new premium product, of course, because it allows them to restore the healthy margins that have been eroded as flat panel televisions have become commodity items. The need for glasses is an insoluble issue, though, and economies of scale will only have a limited impact on prices.

Given all these concerns – and the fact that it is still only a small fraction of the audience that is watching HD, as opposed to owning an HD-ready television, and the fact that the 3D cinema audience declines with every new 3D blockbuster film – we see stereoscopic 3D television remaining very much a niche product. Take up will be slow, and the business case for broadcasters will be difficult to make.

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