3D Video Primer: Part 1

How it began - the History of 3D Cinema

The stereoscopic era of motion pictures began in the late 1890s, when British film pioneer William Friese-Greene filed a patent for a 3D movie process. In his process, two films are projected side by side on a screen and the film is viewed through a stereoscope. In 1900, American inventor Frederick Eugene Ives patented a stereo camera rig which featured two lenses coupled together, and throughout the 1920s and 30s innovation was swift. The 1930s also saw the birth of polarized 3D, which remains the standard even now, more than 80 years later.

In the late 1960s, so-called 'Space-Vision 3D' was developed. In a 'space-vision' system, two images are printed one above the other, in a single frame of film and projected through a single projector fitted with a special polarizing lens. Careful synchronization of left and right channels became unnecessary (early on, badly synchronized 3D films were a huge cause of audience complaints), and footage could be presented in widescreen.

The arrival of IMAX in the 1980s revitalized 3D fimmaking, and until the dawn of the 21st century, 3D lived mostly in the special attractions realm, fuelled by IMAX's expanding 3D network. In 2003, James Cameron's Ghosts of the Abyss was released as the first full-length 3D IMAX feature filmed with the HD Reality Camera System.

In 2009, Cameron's 3D epic Avatar was released to great critical and audience acclaim, and heralded a whole raft of new 3D releases. More than 40 3D movies are scheduled to be released in 2011 – an unprecedented number in the history of 3D cinema, and the same number or more are projected for release in 2012.

Watching in 3D - Glasses on, or Glasses off?

Think 3D and you probably think of cardboard glasses with one green lens and one red. These are anaglyph 3D glasses, and belong to the earliest days of 3D filmmaking. Even during the first '3D craze' of the 30s through to the 1950s though, the anaglyph method was hardly used at all in theatres. For more than 80 years, the most popular way of viewing 3D has been using polarizing systems.

Polarized 3D has been the standard for color 3D video for decades. A major downside to polarized 3D systems is that the glasses block out quite a lot of light, reducing brightness. The footage has to be projected at a high brightness level to compensate, with the result that tonal range and color saturation is reduced.

The third glasses-based 3D viewing method is the so-called 'eclipse', or 'shuttering' system, where left and right channels are projected alternately on the same screen, and LCD 'shutters' in special lenses block each eye in turn, in sync with the display. Some light is blocked, but tonal range is wider and colors are more natural in a shuttering 3D system compared to polarization, and almost all 3D televisions use shuttering technology. There are downsides to shuttering though – the glasses are powered by batteries, so they are heavier and bulkier than polarizing glasses, and because of the technology built into them they are also far more expensive (for the moment). 

'Classic' 3D glasses are used to view anaglyph 3D film and images, which are perceived as monochrome. As such, anaglyph 3D works well enough with black and white images and footage, but can't provide a full-color 3D experience.
In a polarizing 3D system, two images are superimposed through different, mutually orthogonal (at 90 degrees to one another) polarizing filters. For the sake of clarity, this image shows two separate projectors, each fitted with its own filter.

The viewer wears inexpensive glasses that also have mutually orthogonal polarizing filters over each eye, with the result that the left eye only sees the left channel, and the right, the right. The brain then obediently combines the two images into one 3D picture.

Unlike anaglyph and polarizing 3D, where the left/right images are viewed simultaneously, in an eclipse, or shuttering system, they alternate rapidly so that the screen only ever shows a single channel at a time. To create a 3D experience, the viewer wears LCD glasses that 'shutter' each eye continuously and very quickly, in sync with the screen projection so that the brain is fooled into seeing a single unified 3D image.

Glasses off (Autostereo)

For obvious reasons, glasses-free, or 'autostereo' 3D is the holy grail of 3D imaging. Currently, there are two primary forms of autostereo displays on the market - lenticular and parallax barrier. Sony and JVC both use parallax-barrier screens on their 3D camcorders, and Sony offers an optional lenticular screen for some of its Vaio Laptops. 

In a lenticular 3D screen, images are displayed with the left and right channels interlaced in alternating vertical strips. Lens arrays are overlaid vertically on the display, which magnify the left and right channel 'strips' in opposing directions, so that at the correct viewing distance, the viewer's left eye sees only the left channel picture, and the right eye, the right, making a 3D image.
The principle behind parallax barrier screens is very similar. In a parallax-barrier screen, instead of lenses, physical barriers block the left/right channels when the viewer's eyes are aligned correctly with the screen.

One of the downsides of both lenticular and parallax-barrier screens is obvious if you've ever received a 3D postcard – if you move your head, or get too close or far away from the screen, the effect breaks down. Displays like this work reasonably well in portable devices like the Nintendo 3DS and Sony's TD10 because their screens are small, but scaling up is very expensive. Another issue is that both lenticular and parallax-barrier screens reduce overall image resolution, which has unpleasant consequences for the image quality of 2D footage. To compensate, any future big-screen autostereo TVs will need to have a much greater resolution than today's HD models.

3D Cinema: Go Out, or Stay at Home?

In the past, watching a movie in 3D meant heading out to the local cinema, but these days consumers have a choice. If you go shopping for a new TV, you'll see plenty of models that boast '3D compatibility', and as well as a growing number of 3D Blu-ray releases, 3D content is also available on several television channels worldwide. At the time of writing, the number of 3D channels is still small (15 channels globally, of which five are available in the US, and two in the UK) but if industry analysts are correct availability of 3D content will grow considerably in the months and years ahead.

This process will take time though, and right now, most 3D movies are watched in the traditional way – in movie theatres. But there are indications that consumers might not be quite so in love with 3D as the film industry has hoped they might be, and arguably needs them to be. According to Box Office Mojo and BTIG Research Estimates, 3D ticket sales flattened out in the first quarter of 2011. In 2010, 3D ticket sales totaled about 67 percent of the total box office revenue. As of early summer 2011, they were at 64.5 percent, a drop compared to the 2009-2010 increase of more than 5 percent.

After its release in 2009, James Cameron's 3D epic, 'Avatar' became one of the highest-grossing movies ever, eventually earning more than $2.6 billion at the end of its first theatrical release, and has been credited by many industry analysts with reinvigorating 3D filmmaking. A combination of computer-generated footage and live action, Avatar was filmed using stereoscopic cameras.

Price is certainly a factor. The cost of cinema tickets continues to rise, and watching a 3D release only bumps the price up further. Nick Dager, an analyst with the Gerson Lehrman Group as well and editor and publisher of Digital Cinema Report and IndieFilm3D feels that audiences have been simply been burned too many times by inferior 3D content. "Consumers are turning away from 3D movies when they don't believe that it adds anything to the story".

He could be right. It is certainly true that in the wake of the massive success of James Cameron's 'Avatar' - the movie credited by many analysts with reinvigorating 3D cinema - a lot of studios have found out the hard way that simply making a movie in 3D is not enough to guarantee huge takings at the box office. It is probably no coincidence that the 3D movies which garner the best critical reception (like Avatar, and DreamWorks' Kung Fu Panda 2) tend to be those that boast the healthiest 3D ticket sales compared to conventional 2D.

Despite some sobering figures, Andy Bubala, Sony Electronic's Camcorder Business Director is bullish. "We're going to be sitting around in 30 years trying to remember what 2D looked like" he confidently predicts. Whether or not he's right remains to be seen, but television and camcorder manufacturers, as well as film studios, are certainly banking on the enormous potential of the new technology.

In Part 2 of this article we'll be looking at consumer-level 3D video and stills, and the success (or not) of the major electronics manufacturers in getting 3D into consumers' homes.

Click here to read Part 2 of our 3D Video Primer 

Barnaby Britton is Editor of dpreview.com. Valentina Valentini is a freelance journalist based in Los Angeles. You can see more of her work at her website, www.valentinavalentini.com