A composite of 3D images

Mobile 3D displays search for a breakthrough

Smartphone makers are trying to squeeze the third dimension into their flat slabs, but is it worth the struggle?

Cinemas showed close to 50 films in 3D form last year. Since its first boom period in the Hollywood movies of the early 1950s, 3D has gone in and out of fashion, but the latest resurgence in the idea of trying to emulate the way the real world looks is leaking out to other areas, such as TV and mobile.

The problem is that, although people will accept wearing 3D specs in the darkened environment of an Imax cinema, they are not going to be acceptable in most other places. Even in the home, 3D TVs that require users to wear stereoscopic glasses have not captivated many consumers. The problem is potentially even worse when trying to bring 3D content, such as games and navigation assistance, to people on the move. The industry has realised it needs screens that can display 3D scenes without demanding glasses to create a convincing stereoscopic image. Convincing consumers they are worthwhile is another matter.

Smartphones released with 3D-capable displays have appeared on the market. Sharp, which has experimented with portable 3D for a number of years on its laptop computers launched the Aquos in 2012, although that was after the unveiling of the HTC Evo 3D in 2011. Neither phone was a big seller.

Jon Peddie, president of Jon Peddie Research, says: "The problem was, and probably still is, poor brightness, as you lose up to 50 per cent when the 3D screen is on. Also the standard of 3D content available has been poor. So far the majority of the content is games, and they aren't very good games."

Researchers and other manufacturers are experimenting with 3D, but Paul Gray, director of European research at DisplaySearch, is not convinced that they need to bother: "There have been several 3D phones that have not seen high-volume sales as 3D incurs a resolution penalty, and the expectation is for a bright, pin-sharp display, whereas 3D will look grainy, dim and demand more power."

California-based Snail Games claimed it would be one of those to change that at the International CES tradeshow in Las Vegas at the start of 2015. The company revealed its new W3D gaming smartphone, which includes physical gaming controls, similar to those found on the PlayStation Vita, and a screen that simulates 3D behaviour on a conventional LCD. The Android 'phablet' device - midway between a phone and tablet - has the added feature of eye-tracking technology to provide users with glasses-free 3D effects on the screen.

Similar to techniques used on the Nintendo 3DS, by tracking the user's gaze, software can dynamically render content so that it appears to move within a 3D space without the need to split the screen using tiny lenses to direct the light so that each eye sees a different images. The first version was launched in China at the start of the year and the company says it has plans to roll it out in the US and Europe later this year.

Amazon's 3D Fire phone employed a similar approach, although with a focus on 3D-assisted navigation and browsing. Despite a big launch, the design failed to excite much consumer interest. Many tech reviews gave it a middle-of-the-road three-star rating with many commenting on how odd some of the rendering appears, especially when looking at menus.

But some researchers and manufacturers believe that if the quality of the 3D experience on mobiles can be improved it will actually generate a big demand that goes beyond using it just for movies and gaming.

Creating true 3D

In 2014, a team of researchers from the Universities of Manitoba, Toulouse and Bristol wrote a paper that described ways to present 3D on mobile devices in the best way possible.

The research involved using 3D capabilities with apps for interior design and mapping to look at the possibilities for future mobile designs and also to identify the possible barriers to introducing 3D as standard, based on how users interact with the device.

In order to enable manufacturers to develop the technologies that deliver an improved true-3D mobile experience the team identified that first they need to know several things: the ideal angular position, size and distance of the 3D projection relative to the mobile device the image is being viewed on; the projection limits on visual search and direct interaction; and how to coordinate the mobile device and true-3D views.

To find the answers they were looking for the team created a mobile multi-display true-3D prototype in an immersive environment made up of a projection wall and floor and carried out a number of experiments within it. The first was to identify the optimum display properties and the second, touch and interaction. The results then informed the design of the 3D interior design and mapping apps and revealed the parameters that would provide mobile true-3D displays that provide users with a convincing experience.

Revealing these answers is all very well but is 3D capability on mobile devices a feature that people actually want? Tina Teng, a senior analyst of smartphones at DisplaySearch, doesn't necessarily think it is. "When you look at the barriers to implementing 3D mobile devices there are definite questions about whether the 3D effect is a feature that would guarantee more sales," she says, "and there are also questions about whether consumers are comfortable looking at 3D glass and not feeling disoriented or sick."

Depth techniques

Whether it's a feature that people want and will enable manufacturers to shift them in large volumes or not, many companies are still focused on developing 3D mobile devices and accessories. Singapore-based Nanoveu has created a thin-film product, EyeFly3D, which it claims delivers distortion-free 2D/3D video, photos and games on smartphones and tablets. The EyeFly 3D screen is covered in microscopic lenses less than one thousandth of a millimetre in size that the company claims deliver a true-3D experience without suffering from the resolution issues of previous designs smartphones have been known for. The company has developed a range of apps and 3D content to make use of the microlens overlay - organising the pixel display to take account of which eye is most likely to see each one when passed through its associated lens.

Also in 2014 the Chinese firm Takee released what it's claiming is the world's first 'holographic phone', picking up an innovation award from the 2015 CES organisers. Rather than projecting a hologram, the Takee 1 tracks both eyes in order to generate images on an LCD that for a viewer close to the screen will appear to be stereoscopic.

A research team based in California has built a prototype 3D display that uses a closer match to actual holography. In principle, it could be used to create videos that seem to emerge from within a tablet, mobile phone or wrist watch and can be viewed from a range of angles.

Physicist David Fattal, who led the team at Hewlett Packard's Palo Alto research lab, has since set up a spin-off company, LEIA, named after Princess Leia of 'Star Wars' for the point where she appears as a holographic recording in the film. The key to the approach is backlighting.

Backlighting is big news in the 3D world and it's how it will deliver the quality experience that we've come to expect from digital technologies and how LEIA's proposed holograms will become a reality. It's all about the pixels and viewing angles. According to a paper published by Fattal and colleagues in the journal Nature last year, backlit multi-view 3D displays can project the correct perspectives of a 3D image in many spatial directions simultaneously to give a 3D stereoscopic experience without the need for special glasses or eye-tracking.

One of the reasons why 3D phones have not been that impressive so far is because none of the leading multi-view 3D solutions is particularly well suited to mobile devices, as they need a combination of a thin, portable form factor with a high spatial resolution and a wide full-parallax view zone, for short viewing distance from potentially steep angles.

The multi-directional diffractive backlight technology that Fattal and his team have developed allows the rendering of high-resolution, full-parallax 3D images in a very wide view zone - up to 180 degrees in principle - with an observation distance of up to a metre.

The system works by diverting the photons from light-emitting diodes (LEDs) in the backlight through a flat transparent light guide that quickly scans across the viewing range. A shutter modulates the light from the diode as the light guide scans, so that each discrete direction gets a specific intensity of light. As a result, the image shown at each angle is slightly different. As with a conventional 2D display, the light beams from red, green and blue LEDs are steered independently so they combine into a full-colour image at each viewing angle.

To illustrate the capabilities of this technology, Fattal's team used simple ink masks and a high-resolution commercial LCD unit to demonstrate both passive and active modulation with a 64-view backlight. The light guide ran at 30 frames per second and provided 64 viewing angles. The 3D images had a spatial resolution of 88 pixels per inch over a view zone of 90 degrees.

Finding a market

Despite the issues that have plagued 3D phones to date, it seems technology is on the way that can deliver 3D visualisation on the move without glasses. But the market may remain the biggest obstacle. In IT, for example, 3D has not been a success when it comes to user interfaces, at least so far.

Gray says: "For smartphone and tablet applications there seem to be few user-interface problems that actually require 3D."

Teng adds that the mobile market itself brings its own problems: "It's more challenging than having 3D TV."

As manufacturers have discovered, 3D TV has not yet been a raging success. But maybe when the manufacturers get it right and produce a phone that does deliver a truly quality 3D experience, we will all end up wanting one, or thinking that we need one. After all, it's really not that long ago that Apple reinvigorated the smartphone segment with user-interface changes that had eluded its predecessors.

If 3D on the move becomes a desirable reality, how long will it be before we come to expect, and demand, a 3D experience with all our devices? Realistically, if we're having an immersive experience on our phones and tablets then we're definitely going to expect it on our TVs aren't we?

The analysts remain doubtful. Gray says: "We are seeing a decline in 3D as a feature in TV shipments. The experience simply wasn't good enough, there is little content to watch and what content generation there was is also declining."

It seems that 3D TV is not currently on the radar for the big manufacturers either, as all the TV talk at CES 2015 was about High Dynamic Range, which uses more colours, more light and more contrast to create ultra-realistic imagery. Surely once we've got used to that we'll be expecting more again and 3D is the route that we'll have to go down?

Gray thinks not: "All in all I am pretty sceptical about its chances. The only chance for stereo vision at present is VR goggles where 3D and depth perception add significantly to some game playability. Even then I suspect that will be a niche gaming market."

So far, consumer opinion on 3D has not been very positive. 3D TV displays that don't use glasses are not of an acceptable quality for consumer product usage. In the case of TVs, the need to sit within a defined viewing zone is problematic, and any movement while viewing causes a noticeable image distortion.

Peddie agrees with Gray: "I think it will be a long time before 3D TVs become the norm, if ever. The compromises on viewing angle, brightness, and content designed to actually make good use of depth, not just pushing things out at you, are significant hurdles to overcome. And then there is content. If there was compelling content, viewers would put up with a lot of other factors - remember, we were quite happy watching small-screen 2D flickering black and white TV because the content was so exciting."

There have also been mutterings in online reviews that the likes of Samsung, LG and Sony really need to concentrate on getting their smart TVs up to scratch before they try and get the 3D element right. The kind of criticisms that have been levelled at 3D phones around lack of image resolution and clarity are the same ones that people are making about smart TVs.

If we look at the rate of progress made in the past few years, it doesn't seem unrealistic to expect that we could see the next few deliver major advances. Someone will always keep on trying until they get it right and someone out there will always be the first to buy it and lead the way. Let's not forget that analysts and market researchers said the Sony Walkman wouldn't find a market.

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