RealD Cinema is a digital 3D stereoscopic projection technology which does not require two projectors

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By Srivenkat Bulemoni, Filmmaking Techniques

 

RealD Cinema is a digital 3D stereoscopic projection technology which does not require two projectors, unlike some older 3D stereoscopic projection technology. A high-resolution digital projector using Texas Instruments' DLP Cinema technology is used.

 

Technology

The RealD 3-D system is based on the push-pull electro-optical modulator called the ZScreen invented by Lenny Lipton, an American inventor.

 

The technique that RealD uses is comparable to the traditional method of 3-D imaging which uses linearly polarized glasses. The traditional method works by projecting two differently linearly polarized images onto the same screen, polarized at +45° and -45° from the horizontal, which are then filtered by linearly polarized glasses worn by the audience. This type of 3-D imaging requires two projectors, and suffers from visible double-imaging if the head is tilted to the side which places the glasses at an inappropriate angle.

 

RealD however uses a single projector that alternately projects the right-eye frame and left-eye frame, and circularly polarizes these frames, clockwise for the right-eye and counterclockwise for the left-eye, using a liquid-crystal screen placed in front of the projector lens. Circularly polarized glasses make sure each eye sees only "its own" picture, even if the head is tilted. The very high framerate, which is 72 frames per second per eye, makes sure the image looks continuous. In RealD Cinema, each frame is projected three times to reduce flicker, as the source video is usually 24 frames per second. The result is a seamless 3-D picture that seems to extend behind and in front of the screen itself.

 

Films featured using Real D

The first film released using this format was 2005's Chicken Little. For this release, the computer-animated film was re-rendered in 3-D by Industrial Light and Magic and exhibited on RealD Cinema Systems using Dolby Digital Cinema servers.

 

The 3D version of Chicken Little has so far earned about 2.5 times as much per screen as the flat version. When the movie was first shown in 2005, fewer than 100 theaters around the US were equipped to show the movie in 3D. These statistics are difficult to correlate on their own given the many unknown factors involved.

 

Also, a stereoscopic 3D version of the film Monster House was released in approximately 200 theaters equipped for RealD Cinema. In October 2006 and again in October 2007 The Nightmare Before Christmas was re-released in this technique as well.

 

Meet the Robinsons was released March 30th, 2007, in both traditional "flat" and "3D" versions of the film. The film was converted to stereo by Digital Domain. Some estimate over 700 screens for the 3D release of the film. That would make this release the largest up to that date using the RealD system.

 

Beowulf, directed by Robert Zemeckis, released in November 2007 is another film that uses the RealD 3D technology. Beowulf opened on close to 900 RealD screens. RealD at that point had passed its stated milestone of 1,000 global RealD screens installed for the release of Beowulf.

 

Hannah Montana & Miley Cyrus: The Best of Both Worlds Concert was released on February 1st, 2008, and marks another in the Disney stable of 3D films. Hannah Montana & Miley Cyrus: Best of Both Worlds Concert was only shown on digital 3D screens, 97% of which are RealD 3D screens, and brought in $31 million in its opening weekend, virtually all of which was generated in RealD theaters. (Disney Digital 3D films do not exhibit in IMAX 3D theaters, which utilize an analog technology).

 

U2 3D, U2's concert film based on the Vertigo Tour, debuted in RealD in 2008. The film was exhibited in both IMAX 3D and RealD Cinema.