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RealD Cinema is a digital stereoscopic projection technology made and sold by RealD Inc. It is currently the most widely used technology for watching 3-D films in theatres.^[1]

Technology

Two pairs of RealD glasses demonstrating the polarization effect

Looking into a mirror with just one eye, the lens over the open eye will always appear darkly tinted in the reflection. In this photo, a mirror is between the background and foreground images of the glasses.

RealD 3D cinema technology uses circularly polarized light to produce stereoscopic image projection. Circular polarization technology has the advantage over linear polarization methods in that viewers are able to tilt their head and look about the theater naturally without seeing double or darkened images.^[2] Despite this advantage, any significant head tilt will result in incorrect parallax and prevent the brain from correctly fusing the stereoscopic images.

Because RealD 3D cinema technology utilizes a single projector solution, it suffers from two primary disadvantages. First, the system causes "significant light loss"; RealD estimates the viewer sees about 35% of the light when viewing RealD 3D when compared to a similarly projected 2D image on a standard white screen.^[2]

The high-resolution, digital cinema grade video projector alternately projects right-eye frames and left-eye frames 144 times per second.^[2] The projector is either a Texas Instruments' Digital Light Processing device or Sony's reflective LCOS (Liquid crystal on silicon). A push-pull electro-optical liquid crystal modulator called a ZScreen is placed immediately in front of the projector lens to alternately polarize each frame. It circularly polarizes the frames clockwise for the right eye and counterclockwise for the left eye. The audience wears spectacles with oppositely circularly polarized lenses to ensure each eye sees only its designated frame, even if the head is tilted. In RealD Cinema, each frame is projected three times to reduce flicker, a system called triple flash. The source video is usually produced at 24 frames per second per eye (total 48 frames/s), which may result in subtle ghosting and stuttering on horizontal camera movements. A silver screen is used to maintain the light polarization upon reflection and to reduce reflection loss to counter the inherent losses by the polarization filters. The result is a 3D picture that seems to extend behind and in front of the screen itself.^[3]

Viewing comfort

3D systems for movies using polarized light cause a loss of screen brightness due to the inherent filter absorption. The polarization filter in front of the projector blocks half of the projected light, reducing screen brightness. However, as half of all other ambient and reflected light in the theater is also reduced by the viewing lenses, the perceived contrast does not suffer excessively.^{[citation needed]} The overall effect is that of wearing a pair of slightly darkened glasses in a standard movie theater, which could be compensated for by using brighter projector lamps.

Some viewers of 3D movies complain of headaches or nausea during or even after viewing.^[4]^[5] Those problems can be caused by the viewer tilting his or her head, making it harder for the brain to fuse the two images (due to parallax mismatch between the eyes and the cameras). It can also be caused by rapid transitions in the movie between scenes of very different depth. Directors and editors of 3D movies consequently try to avoid such transitions.^[6]

Other systems that use circular polarization

Samsung will be using RealD technology in its upcoming HDTVs.^[3]. At IBC 2011 in Amsterdam RAI several companies, including Sony, Panasonic, JVC & LG (among others) highlighted their upcoming 3D stereoscopic product portfolios for both the professional and consumer markets to use the same polarization technique as RealD 3D Cinema uses for stereoscopy. These highlighted products cover everything from recording, projecting, viewing and digital display technologies to live, recorded and pre- and post production facilities and soft- and hardware based product to facilitate 3D content creation. Their systems are interpretable, and compatible with existing, passive RealD 3D glasses.^{[citation needed]}

References

^ Verrier, Richard (2009-03-26). "3-D technology firm RealD has starring role at movie theaters". Los Angeles Times. Retrieved 2011-02-05.
^ ^a ^b ^c Cowan, Matt. "Real D 3D Theatrical System" (PDF). European Digital Cinema Forum. Retrieved 2009-03-28. Cite error: The named reference "overview" was defined multiple times with different content (see the help page).
^ ^a ^b Cowan, Matt. "Presentations (technical)". RealD Media Room downloadable files. Retrieved 2009-03-28. Cite error: The named reference "reald" was defined multiple times with different content (see the help page).
^ Watt, Nick (2009-12-19). "Will 'Avatar' Make Viewers Nauseous? The 3D Effects in Blockbuster Movie 'Avatar' Are Claimed to Be 'Vomit Inducing'". ABC news.
^ "How to avoid getting a 3D headache while watching Avatar". Shadowlocked. 2009-12-21.
^ Needleman, Rafe (2009-06-18). "3D means new rules for directors".

External links

RealD website
RealD Cinema page
RealD Theater Locator
Dolby Digital 3D vs Real D / Master image systems Video Technology Blog
Who is Lenny Lipton? About Inventor and Chief technical officer of RealD through 2008

[1] Verrier, Richard (2009-03-26). "3-D technology firm RealD has starring role at movie theaters". Los Angeles Times. Retrieved 2011-02-05.

[overview-2] Cowan, Matt. "Real D 3D Theatrical System" (PDF). European Digital Cinema Forum. Retrieved 2009-03-28. Cite error: The named reference "overview" was defined multiple times with different content (see the help page).

[reald-3] Cowan, Matt. "Presentations (technical)". RealD Media Room downloadable files. Retrieved 2009-03-28. Cite error: The named reference "reald" was defined multiple times with different content (see the help page).

[4] Watt, Nick (2009-12-19). "Will 'Avatar' Make Viewers Nauseous? The 3D Effects in Blockbuster Movie 'Avatar' Are Claimed to Be 'Vomit Inducing'". ABC news.

[5] "How to avoid getting a 3D headache while watching Avatar". Shadowlocked. 2009-12-21.

[6] Needleman, Rafe (2009-06-18). "3D means new rules for directors".

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@@ Line 10: / Line 10: @@
 |accessdate=2009-03-28|last=Cowan|first=Matt|work=European Digital Cinema Forum}}</ref> Despite this advantage, any significant head tilt will result in incorrect parallax and prevent the brain from correctly fusing the stereoscopic images.
-Because RealD 3D cinema technology utilizes a single projector solution, it suffers from two primary disadvantages.  First, the system causes "significant light loss"; RealD estimates the viewer sees about 35% of the light when viewing RealD 3D when compared to a similarly projected 2D image on a standard white screen.<ref name=overview>{{cite web|url=http://www.edcf.net/edcf_docs/real-d.pdf|title=Real D 3D Theatrical System|accessdate=2009-03-28|last=Cowan|first=Matt|work=European Digital Cinema Forum}}</ref>  The single projector solution also results in a halving of horizontal resolution.  For example, [[Sony]]'s 4K SXRD imaging device, which projects a 4K 2D image, will produce a 2K-per-eye 3D image.<ref name=resolution>{{cite web|url=http://www.reald.com/content/cinemaProducts.aspx?pageID=13|title=Creating the RealD 3D Experience - XLS Cinema System|accessdate=2011-05-22}}</ref>
+Because RealD 3D cinema technology utilizes a single projector solution, it suffers from two primary disadvantages.  First, the system causes "significant light loss"; RealD estimates the viewer sees about 35% of the light when viewing RealD 3D when compared to a similarly projected 2D image on a standard white screen.<ref name=overview>{{cite web|url=http://www.edcf.net/edcf_docs/real-d.pdf|title=Real D 3D Theatrical System|accessdate=2009-03-28|last=Cowan|first=Matt|work=European Digital Cinema Forum}}</ref>
 The high-resolution, [[digital cinema]] grade [[video projector]] alternately projects right-eye frames and left-eye frames 144 times per second.<ref name=overview>{{cite web|url=http://www.edcf.net/edcf_docs/real-d.pdf|title=Real D 3D Theatrical System|accessdate=2009-03-28|last=Cowan|first=Matt|work=European Digital Cinema Forum}}</ref> The projector is either a [[Texas Instruments]]' [[Digital Light Processing]] device or [[Sony]]'s  reflective LCOS ([[Liquid crystal on silicon]]). A push-pull [[Electro-optics|electro-optical]] [[liquid crystal]] modulator called a [[ZScreen]] is placed immediately in front of the projector lens to alternately polarize each frame. It circularly polarizes the frames clockwise for the right eye and counterclockwise for the left eye. The audience wears spectacles with [[Stereoscopy#Circularly polarized glasses|oppositely circularly polarized lenses]] to ensure each eye sees only its designated frame, even if the head is tilted. In RealD Cinema, each frame is projected three times to reduce flicker, a system called triple flash. The source video is usually produced at 24 frames per second per eye (total 48 frames/s), which may result in subtle [[motion blur|ghosting]] and stuttering on horizontal camera movements. A [[silver screen]] is used to maintain the light polarization upon reflection and to reduce reflection loss to counter the inherent losses by the polarization filters. The result is a 3D picture that seems to extend behind and in front of the screen itself.<ref name=reald>{{cite web|url=http://www.reald.com/Content/Presentations.aspx|title=Presentations (technical)|accessdate=2009-03-28|last=Cowan|first=Matt|work= RealD Media Room downloadable files}}</ref>