Differences Between IMAX, RealD 3D, and Dolby Digital 3D Theaters

Watching a movie in a 3D theater typically uses any of the three popular theatrical 3D systems: IMAX, RealD 3D, or Dolby Digital 3D. They are currently the leading competitors offering theater owners the technical system required to build a new 3D theater or convert an existing 2D theater into a 3D one. Each 3D system may have differences, but all of them have one thing in common: they require the viewers to wear 3D glasses to see a movie with three-dimensional depth.

IMAX

IMAX is a film-based motion picture format that generally offers greater image resolution compared to conventional film systems. Using its own proprietary cinema projection standards distinct of its large-size and curved screen, IMAX can show a 2D or 3D presentation by either upconverting the content into IMAX format or shooting the film using the IMAX system.

The illusion of 3D depth comes from a projection that uses linear polarization of the movie's left and right images (each image meant for each eye). The polarization makes it possible to cancel out one of the two images seen by the viewer so one eye only sees the actual image meant for it. However, the problem with linear polarization is that the person can maximize the 3D view only at a certain angle. This means that too much head movements can affect the quality of 3D image seen on screen.

Newer developments now provide digital options using IMAX technology. The IMAX Digital Theatre System is a projection standard that showcases audio-visual content either in 2D or 3D format using DCI or IMAX digital format. However, this offers a much lower resolution compared to what the normal IMAX film format offers.

RealD 3D

RealD 3D uses digital stereoscopic projection technology with a circular polarizing system. Although an IMAX screen is beneficial to the audience because of its larger screen, its linear polarization is inferior to circular polarization technology because the latter allows viewers to move their heads any time when watching the movie without really affecting the quality of 3D images seen on screen.

Glasses used in RealD 3D are not expensive to produce. However, the theater requires a special type of silver screen that can keep up with the polarization needs of the stereoscopic images being projected. The challenge on this type of screen is that it can possibly produce reflection issues on the viewer, which is not a concern when watching movies on white screens. Unlike IMAX and Dolby Digital 3D theaters that can project both 2D and 3D content, a RealD 3D theater is solely meant for 3D digital projection because of the specific projector and projection screen requirements its theatrical set-up needs.

Dolby Digital 3D

Dolby Digital 3D also uses a digital stereoscopic projection technology with circular polarizing system. It requires a special type of 3D glasses with special multi-coated lenses, which make it more expensive and fragile compared to the ones used in RealD 3D. The projection screen required in a Dolby Digital 3D system is actually the same as the one used for a standard 2D digital projection screen. This solves the silver screen reflection issues encountered in a RealD 3D theater.

Even the standard 2D digital cinema projector used in Dolby Digital Cinema systems can be used for 3D projection by simply adding an accessory called a rotating filter assembly to the projector. This is inserted in between the projector's lamp and picture element. The rotating filter wheel assembly simply retracts when showing a 2D presentation. This provides the theater the flexibility to showcase both 2D and 3D content.