3DTV – What to believe

December 06, 2010
For an informed view on connected entertainment in the UK & Ireland, visit Cue Entertainment 

Depending on where you saw the story, it has been a good or bad week for stereoscopic 3DTV. 

Close one eye and you learn that 3DTV is “selling faster than HDTV” (Futuresource Consulting). Close the other and you read that, “Disappointing 3DTV sales loom for holiday season” (Broadcast Engineering). Close both eyes and you realise that most of us are still completely in the dark as far as 3D technology is concerned and that this applies as much to those people working in the industry as it does to the confused consumer.

Shoppers are skilled at rapid cost-benefit analysis when confronted with new technology, although they do not always understand what is inside the box. Flat screens and connected television sets passed the test; for the moment, 3DTV and 3D Blu-ray have failed it.

Although this is a simplistic assessment, spending money on big-ticket consumer electronic products in times of hardship must provide instant gratification 24/7. The possibility of football and feature films in 3D at some time in the future is poor recompense for handing over the best part of £1,000.

With the money saved, potential customers can buy a bigger TV than the folks next door and still have enough left over for a night out at the local 3D cinema. There has to be a reason to motivate investment in a 3D home system: a bundled copy of “Avatar” or “Toy Story 3” is scarcely enough.

Experience shows that a critical mass of content must be available before a new format captures public enthusiasm. When flat screens first appeared, content was available already from broadcast TV, satellite, cable or packaged media. Wide-screen 16x9 tube TV sets the size and weight of small armchair had become too big for the average living room. Even though the picture quality of early flat panels was inferior, there was good reason to swap the bulky box for a screen slim enough to hang on the wall. Consumers had no doubt that content would be there to fill whatever sized screen they could afford.

As flat screens increased steadily in height and width, the depth reduced dramatically and culminated in the prototype OLED TVs of today with have screens that measure just a few millimetres thick. These screens make a fashion statement about the owner that any visitor to the home can see and you don’t need a dorky pair of glasses to appreciate them.

If you believe everything you read, you will know that auto-stereoscopic screens are just around the corner. These miracles of glasses-free technology will soon be in every store at affordable prices, just waiting for customers to take them home and show them off to their friends … or maybe not. The announcement this week that Apple has patented a device that gives a “stereoscopic optical effect” without glasses will probably lead to queues outside Apple stores by next weekend.

Sony Training Services produces an authoritative guide to stereoscopic creation, which is the source of some of the data reproduced here. We learn that the current approach to 3D combines images from two linked cameras spaced about 65mm apart and serve as the virtual eyes of the viewer. In the home, 3D glasses ensure that the left eye sees the image from the left camera and the right eye sees the image from the right camera. Our brain uses the small differences between the left and right picture to calculate which objects are close and which are further away. It is this so-called “depth clue” that creates the impression of a third dimension, known as stereopsis. Stereopsis exploits our binocular (two-eyed) vision in order to create this illusion and only those with sight in both eyes perceive the effect.

Stereopsis is not the only depth cue that we use to judge how near or far things are from us. Eight separate visual elements combine to create true 3D vision, including perspective, relative movement and the effects of light and shade. People with poor or no vision in one eye can still use many of these depth clues to judge relative distances but they are excluded from the stereoscopic TV experience.

For glasses-free technology to work effectively, screens must do more than create the illusion of depth, otherwise they are little better than the “lenticular” 3D picture cards that once came free with packets of bubblegum. A New York company, 3D Fusion, claims to have a “broadcast quality glasses-free screen that will one day replace conventional 2D television” and it is available now.

The company founder is Stephen Blumenthal, an ex-TV repairman, who believes that the left/right stereoscopic approach to 3DTV is fundamentally wrong. A single high-definition video is transmitted as now, together with a second low-resolution “depth metadata” (DMD) image containing information about the distance of each object from the original camera lens.

Existing viewers see a normal HDTV picture, while the mathematical combination of the two signals in the 3D Fusion TV produces nine different views through its lenticular screen and re-creates the depth cues of the original scene without the need for glasses. Binocular vision is not required (though it helps) since a slight movement of the head will provide some of the information that the brain needs to create the 3D illusion.

In October, Blumenthal gave a working demonstration of his glasses-free solution displaying live-action 3D. There is no doubt that it works although some technical issues remain. The company is not alone in exploiting the DMD concept, which would also allow viewers to adjust the depth of the 3D effect themselves, using a remote control. Benefits would accrue at the acquisition stage too and reduce the need for the very accurate alignment of two cameras at each point of view. The scramble at the start of this year to set standards for 3DTV appears suddenly to be a little unwise.

The sports network ESPN committed to a full year trial of 3D but after six months there are doubts about the potential return on investment. At the recent Sports Broadcast Europe conference, Senior Director of Technology Jonathan Pannaman said, “We have to make production efficiencies to make it work. We’ve also got to get more eyeballs looking at 3D to get some idea of acceptance in the marketplace.”

ESPN hopes to identify a way to deliver 3D for little more than the cost of 2D, which is a challenge given their current film-based approach that requires one technical operator for each camera. The company says it has sought ideas from all suppliers and will conduct “a major study into depth analysis and DMD”.

The effective display in 3D of subtitles and captions for the hearing-impaired is a hot topic currently in the US, where closed captions have been compulsory for many years. One commentator wrote, “Subtitles are simply a part of the picture, there is no need for new technology to transmit or display them.” Actually, the addition of text to a 3D image is a challenging task that few have mastered.

Using DMD to control the placement of text in 3D space resolves many of the issues that arise when the action is a long way behind or in front of the plane of the screen. Unfortunately, the PS3, the most widely adopted 3D Blu-ray playback device, does not support this feature and subtitles appear in a single plane. In the rush to set standards, some devices were left behind.

So who do you believe: the enthusiasts in Consumer Electronics companies who have invested hundreds of millions in hardware and attracted no more than a million customers for 3D in the US so far this year? Or the naysayers who believe that it is all right to invest in content acquisition but we should wait for glasses-free screens?

The success of connected TV, especially in North America, could prove decisive. The “2D + DMD” solution requires far less bandwidth than some other proposals, and bandwidth is at a premium when it comes to broadband delivery. Subscription 3D VOD on IPTV could well be the next big thing. 

Remember, you read it here first.