TECHNOLOGY FEATURE VIDEO GUIDE >>>>>>>>>>>>
MAIN DIGITAL 3D SYSTEMS RealD
A passive circular polarisation system, developed by American author, filmmaker, and inventor Lenny Lipton. RealD operates with only one projector, which alternates between the left eye frame and the right eye frame. Each frame is projected three times at a high rate to produce a continuous image. Glasses with Polaroid lenses have to be worn and the picture must be projected on a silver screen.
Dolby 3D
Developed in conjunction with Infitec, a division of Daimler, this is based on spectral filtering. Special filters have to be installed on the projectors, which work from a Dolby server. Dolby 3D also uses passive glasses but, unlike those for RealD, these are based on anaglyph interference filter
3D using the Reality Camera System designed by Vince Pace to Cameron’s specifications. The two later co-founded the Cameron Pace Group (CPG), a leading provider of 3D technology. Cameron’s Avatar (2009)
probably marks the zenith of the new 3D boom, which saw a proliferation of digital systems (see box above). Because they are digital, today’s 3D technologies stabilise the pictures, solving the problem of images that should be viewed by the left eye being seen by the right and vice versa.
As in the past these
systems require people to wear glasses to get the 3D effect. There are two main forms of 3D glasses: passive – based on polarising lenses to interpret the stereoscopic information – and active, or eclipse, which use battery- powered liquid crystal shutters to imperceptivity block each eye alternately so they receive the correct image data. From the ’50s to the ’70s
3D films were usually shot using two cameras, either at right angles to each other and focusing off a half-silvered
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mirror or facing each other with two mirrors arranged at 45-degree angles to the axes of the lenses, which produced the respective right and left eye images. Modern camera rigs are either side-by-side or mirrored. The second arrangement is also known as a beam splitter; one camera shoots straight on while a second points down from above, with a mirror splitting the beams from the subject to get the left and right eye information.
The initial novelty and optimism surrounding 3D cinema has faded over the past two to three years. Television broadcasters were also initially enthusiastic about 3D for the home but that mood has also changed. Sky is still promoting its 3D service but ESPN has pulled out of the technology and the BBC recently announced that it would not be producing any more stereoscopic programmes for at least three years.
REFERENCES The Complete Film Dictionary second edition by Ira Kongigsberg, Penguin Reference 1997
systems – a modern equivalent of the process used for 1950s 3D. This uses different wavelengths of red, green, and blue for each eye and can be shown on a matte white screen rather than a more expensive silver screen.
XpanD 3D
Launched in 2005, this format uses active shutter glasses and infrared technology and is aimed at both theatrical and domestic viewing. In cinemas, XpanD 3D can be projected onto matte white screens but as the glasses are powered by batteries, the cost of implementation is increased, which applies to the home as well.
IMAX 3D
This is shot using separate camera lenses to represent the left and right eyes. Images from each lens feed separate rolls of film, which,
when projected simultaneously, create 3D images on a 2D screen. Viewers watch wearing headsets with left and right liquid crystal lenses.
MasterImage 3D A polarised 3D system working with a projector connected to a spinning polarised filter. This contains alternating segments of circularly polarised material and is mounted on the front of the projector lens. The filter is synchronised to the projected images, with each frame having a polarisation perpendicular to the one that preceded it. The images are watched using polarised glasses.
Other systems include the non-specific Digital 3D standard and the seemingly marginalised Panavision 3D passive system, which uses Omega 3D filters.
>>>>>>>>>>> GLASS-LESS 3D
Perhaps the biggest problem people have with 3D is the need to wear glasses in order to watch it. Glasses-free technology, properly known as autostereoscopy, could revive interest in 3D. Two technologies have been used for autostereoscopy: the lenticular lens or a parallax barrier.
Both operate by showing two, or more, images on the viewing surface in thin, alternating strips. A full picture is created by either the lenticular lens bending the images, or the parallax barrier blocking one of the two strips of the image. The drawback is that to get the full 3D effect a viewer has to be sitting within a very specific, small field of vision almost perpendicular to the screen so their eyes see the correct image corresponding to either left or right. The images are beamed on to a high-gain, corrugated screen, which reflects light at acute angles.
Lenticular technology has made more inroads into
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domestic photography and digital home movies through camera products like the Fujifilm FinePix Real 3D than professional cinema and broadcasting. Leading TV manufacturers have been developing glass- less sets, with Philips now working with Dolby to extend its 3D system for glass-less operation. Dolby says its 3D process is agnostic in terms of delivery and can work with any stereoscopic optics and displays. The basis of the
system is a multiview auto- conversion method that renders the picture and produces it with the correct estimation of depth. During NAB 2013 Dolby and Philips signed an agreement with the Cameron Pace Group (CPG) to integrate Dolby 3D into CPG’s video production chain. The companies stated their belief that glass-less 3D for the home can be improved by using autostereoscopy in the Dolby 3D format.
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