3DTV

3D television (3DTV) is a class of television that conveys depth perception to the viewer by presenting a separate image to each eye, most often using stereoscopic 3D techniques. The format reached the consumer market in 2010 and was promoted heavily by every major television maker for several years before demand collapsed. By January 2017 the last two manufacturers still building 3D sets, Sony and LG, had dropped the feature, ending 3D television as a mass-market product.

Most 3D televisions required the viewer to wear glasses, either battery-powered active-shutter glasses or simpler passive polarized glasses, to separate the left-eye and right-eye images. A smaller number of glasses-free (autostereoscopic) sets used optical layers such as a parallax barrier or lenticular lenses. The same two-view stereoscopic principle that 3D televisions used to create the illusion of depth underlies the displays inside modern virtual reality head-mounted displays, and the rise of consumer VR overlapped with 3DTV's decline. Commentators in the VR and broader technology press have repeatedly used 3D television as a cautionary comparison for VR's commercial prospects.

Background

The technique behind 3D television predates the medium itself. Binocular depth perception relies on each eye seeing a slightly different view of a scene, a property exploited by the stereoscope that Charles Wheatstone described in 1838. Stereoscopic moving images were demonstrated for television as early as 1928 by John Logie Baird, and experimental 3D broadcasts and anaglyph (red-and-cyan) transmissions appeared at intervals over the following decades, but none became a lasting consumer product.

The modern wave of 3D television was driven by cinema. James Cameron's film Avatar, released in December 2009, became the highest-grossing film up to that point and earned far more in 3D and IMAX showings than in standard 2D, which renewed industry interest in selling 3D as a premium home feature. Cameron himself campaigned for 3D in the home, forming a venture with cinematographer Vince Pace to push 3D into episodic television, sports, and advertising.

How it works

A 3D television creates the impression of depth by delivering a different image to each of the viewer's eyes, so that the brain fuses the pair into a single scene with apparent depth, the same effect as ordinary stereoscopic 3D viewing. The sets divided into three broad approaches, two of which required glasses.

In an active-shutter system the screen alternates rapidly between the full left-eye and right-eye frames, while battery-powered glasses contain liquid-crystal shutters that darken each lens in time with the display, so each eye sees only its intended frames. The alternation runs fast enough, commonly cited at around 120 times per second, that the viewer perceives a continuous image. Active glasses send the full panel resolution to each eye but are heavier, need batteries, must stay synchronized with the set, and were generally not interchangeable between brands. Active 3D was the choice of Samsung, Sony, and Panasonic.

In a passive (polarized) system the television displays both eye images at once on alternating lines, with a film-patterned retarder bonded to the panel giving adjacent lines opposite polarization. Inexpensive polarized glasses, similar to those used in cinemas, then route each set of lines to the correct eye. Passive glasses are cheap, light, battery-free, and cross-compatible, but on a 1080-line set each eye receives only about 540 lines of vertical resolution. Passive 3D was favoured by LG and Vizio.

A third approach, autostereoscopic (glasses-free) display, placed an optical layer such as a parallax barrier or lenticular lenses over the screen so that the left-eye and right-eye images reached the viewer's eyes directly. Glasses-free displays worked only within narrow viewing zones and at particular distances; the most successful consumer device using the principle was not a television but Nintendo's handheld 3DS games console of 2011, whose parallax-barrier screen produced its optimal effect only for a viewer centred at roughly average eye separation. Glasses-free 3D televisions remained rare and expensive throughout the period.

Rise and fall

3D-capable sets from Samsung and Panasonic reached buyers in the months after CES 2010, most of them using active-shutter glasses; passive sets from makers such as LG followed within a year or two. Shipments climbed quickly. According to DisplaySearch, worldwide 3D television shipments rose from 2.26 million units in 2010 to 24.14 million in 2011 and a peak of 41.45 million in 2012.

The decline that followed was rapid. The number of 3D viewers began falling in late 2013, and broadcasters retreated from the format: DirecTV wound down its dedicated 3D programming, the BBC suspended its 3D output in July 2013 citing a "lack of public appetite", and ESPN closed its ESPN 3D channel in 2013 for lack of demand. Vizio dropped 3D from its sets around 2013-2014, and Samsung stopped including the feature after the 2016 model year. In January 2017 the two remaining holdouts, Sony and LG, confirmed they would offer no 3D sets in their 2017 ranges, which removed 3D television from the market entirely. LG's Tim Alessi said the company's research showed 3D was "not a top buying consideration" and that "actual usage was not high", and that LG would redirect its effort toward features such as high dynamic range (HDR) that had "much more universal appeal". Sony likewise cited current market trends in deciding not to support 3D for its 2017 models.

The reasons commonly given for the collapse include a persistent shortage of 3D content for the home, the inconvenience and cost of glasses, eye strain and headaches reported by some viewers, and the arrival of 4K and HDR as the new premium selling points for televisions.

3D television timeline

Year	Event
2009	Avatar released in December, reviving cinema and industry interest in 3D
2010	First consumer 3D sets ship after CES; worldwide shipments about 2.26 million
2011	Shipments rise to about 24.14 million; Nintendo 3DS brings glasses-free 3D to a handheld
2012	Shipments peak at about 41.45 million units
2013	Viewer numbers begin to fall; ESPN 3D and BBC 3D programming end
2016	Samsung's last 3D sets; production largely limited to a few premium models
2017	Sony and LG drop 3D from their ranges, ending mass-market 3DTV

Relevance to virtual and augmented reality

3D television and consumer virtual reality use the same underlying display principle. A 3D set, like a VR head-mounted display, works by showing each eye a separate view so that binocular disparity produces a sense of depth. Writing about stereoscopy in IEEE Technology and Society Magazine, Pawel Rotter described a head-mounted display as a device whose user "wears a device with two small displays, one for each eye" together with magnifying lenses, the same two-view stereoscopic arrangement that 3D televisions applied to a single shared screen. In that sense 3D television belongs to the same stereoscopic-3D lineage, running from the Victorian stereoscope through 3D cinema, that the VR revival of the 2010s also drew on.

The timing of the two technologies overlapped. 3D television was failing in the same years that the Oculus Rift and other consumer VR headsets were being launched, which led commentators to ask whether VR would repeat 3DTV's trajectory. In a January 2016 IEEE Spectrum piece headlined "How VR Can Avoid the Fate of 3D TV", Stephen Cass argued that 3D television failed chiefly because there was never enough compelling content to justify the format, and that VR's prospects depended on whether it could deliver content that felt genuinely new rather than on the stereoscopic effect alone. Pawel Rotter, writing in IEEE Technology and Society Magazine, made a more sceptical comparison: he treated a stereoscopic screen as "a substitute for virtual reality" and suggested that the same reluctance to be drawn out of a shared physical room that limited 3D television could also limit home VR adoption.

A further point of contact is the vergence-accommodation conflict, a known source of viewer fatigue in stereoscopic systems, in which the eyes converge on a virtual object at one apparent distance while still focusing on the fixed screen plane. Rotter cited this conflict among the comfort problems of 3D viewing, and it remains an active concern for VR and augmented-reality head-mounted displays, motivating research into varifocal and light-field displays.