RealD 3D theater technology is a
polarized 3D system that uses
circularly polarized light to produce
stereoscopic image projection. The advantage of circular polarization over
linear polarization is that viewers are able to tilt their head and look about the theater naturally without seeing double or darkened images. However, as with other systems, any significant head tilt will result in incorrect
parallax and stop the brain from correctly connecting the stereoscopic images. The high-resolution,
digital cinema grade
video projector alternately projects right-eye frames and left-eye frames, switching between them 144 times per second. The audience wears
circularly polarized glasses that have oppositely
polarized lenses that ensures each eye sees only its designated frame. 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 some of the significant light loss due to polarization filter absorption. The result is a 3D picture that seems to extend behind and in front of the screen itself. ==History==