The Technology

For 3D to become truly ubiquitous, it needs to become more widely available. This requires a major investment from cinema chains worldwide, and to make things more complex there's not just one but four different theatrical 3D technologies on the market, each demanding a different version of the film, different projection technologies, different 3D glasses and - in some cases - a different screen.

The first, and currently the most established, is RealD. RealD uses a single 2K resolution DLP projector with an optical modulator, known as the Z-Screen, sitting in front of the lens. With the movie running at 144fps, the Z-Screen polarises images for the left eye and right eye in opposite circular states; the left-eye signal is polarised in an anti-clockwise direction, while the right-eye signal is polarised clockwise. This light is projected onto a special silver screen, and from there it is reflected into the viewer's eyes through glasses with circular polarised lenses. These separate the left eye and right eye signals and create the stereoscopic image. With each eye getting an effective frame rate of 72fps, the image seems smooth and continuous, and as circular polarisation is more forgiving than the old fashioned horizontal/vertical polarisation, it's easier to get a clear image, whatever angle you sit at.

The second contender is IMAX 3D. This was originally an analogue format which used dual sychronised projectors and polarised lenses, just like the old 3D films of the fifties, but with the benefits of the high-resolution 70mm frame and rock-solid mechanics that make it possible to show IMAX films so large and with such clarity. However, IMAX 3D is now going digital, with a system based on dual 2K projectors using Texas Instruments DLP chips.

The third system comes from one of the biggest names in cinema technology: Dolby. Like RealD, Dolby 3D uses a DLP projector running at a frame rate of 144fps, but Dolby3D uses a specially designed colour filter technology, with the 'interference wheel' dividing the light into six colour bands. One set of shorter wavelengths representing the red, green and blue portions of the image are sent to one eye, while one set of red, green and blue images with longer wavelengths is sent to the other. Coloured glasses filter out the light being sent to the other eye, but without affecting the colour balance in any perceptible way. This instantly rules out one of the major issues with the old anaglyphic 3D technology.

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