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3D stereoscopic film projection system

Aug 21, 2018

The 3D  stereoscopic film projection system uses ordinary polarized dual-machine  3D technology to play the source of the 3D format. There  are three 3D experiences for dual-camera screening, followed by IMAX  3D, normal polarized dual-machine 3D, and Dolby 3D dual-machine. Because IMAX 3D is generally very expensive, the effect of Dolby 3D dual-machine is still limited. Therefore, "Ordinary polarized dual-machine 3D" has become the most cost-effective 3D experience!

Polarized mode
RealD  3D technology is typical of this method. The 3D chip source is a format  with a frame rate of 48fps, and the left and right eye images are 24  frames each. The projection mode of RealD 3D is to change the picture of  3 times of 48fps to 144fps, that is, Each frame of the picture is displayed three times quickly. The  light emitted by the projector is polarized in different polarization  directions by a "Z screen" mounted on the front of the lens. There are  two polarization directions and are synchronized with the frame  switching of the projector to ensure the left and right eyes. The  polarization direction of the light corresponding to the picture is  maintained at 90 degrees orthogonally, and the 3D effect can be  exhibited by the metal screen and the polarized glasses. RealD 3D uses circularly polarized light.
RealD  3D glasses are simple and inexpensive, and comfortable to wear, but all  projections using the principle of polarized light require a metal  screen, increasing the investment in the theater. In  terms of effect, RealD 3D works well, 3D feels very strong, the picture  is basically no flickering, and color reproduction is more accurate. The  weakness is reflected in the fact that the light attenuation is large  and the brightness of the picture is low, which leads to low contrast.  In particular, some theaters reduce the brightness of the projector bulb  in order to save operating costs, so that the brightness of 3D movies  is even worse in stand-alone screening.

Polarized single-machine dual lens
Mainly  used in the Sony 4K projector, this projector has two lenses that can  project left and right eye images at the same time, so it is called a  no-timer projector. The general brightness of such  projectors is relatively high, and the actual viewing is not even worse  than the sum of the two projectors. Integrating RealD 3D technology on Sony 4K projectors seems to be a strategic partnership between the two companies. Since  there is no time difference, the flickering of the screen will be  completely eliminated, and the other principles are not much different  from ordinary RealD 3D. I haven't seen the actual  effect yet, but in principle, as long as the brightness problem is  solved, there should be no essential difference between this method and  the dual-machine show. So the effect is worth looking forward to.

Polarized mode
3.1 IMAX 3D
IMAX Digital is springing up due to lower cost and IMAX's signature  sign, the shrinking version of the IMAX experience, and IMAX 3D is an  important magic weapon to make IMAX Digital superior to ordinary  theaters.
IMAX  3D uses two special projectors to display the left and right eye images  respectively. Through the polarizing filter, the light from the left  and right eye images becomes linearly polarized light in the opposite  direction, and then through the reflection of the metal screen, enters  the polarized glasses worn by the audience, and finally forms 3D. Vision. IMAX  glasses are thin but large in size and comfortable to wear. The biggest  feature is that the 3D picture is extremely bright, almost as bright as  2D. The 3D image is very strong and very stable, and the 3D scene is close to the eye, which seems to be within reach. The colors are really true, and it is really much better than the 3D effect of ordinary theaters. There is almost no crosstalk between the left and right eyes, and there is no 3D picture ghosting, color bleed and flickering. IMAX  3D does not have any pressure on the human eye. It does not cause  discomfort to the eyes because of long-term light. However, some people  will feel dizzy because of the particularly strong 3D intrusion, which  also illustrates the charm of the IMAX 3D experience.

3.2 ordinary dual-machine 3D (shadow 3D stereoscopic film projection system)
The  difference between the 3D stereoscopic film projection system and the  ordinary dual-machine 3D and IMAX is that circularly polarized light is  used, and other aspects are similar. The benefits  are also obvious. The advantages of IMAX3D are also inherited in the  common dual-machine 3D, but it saves a lot of cost and brings benefits  to the audience. However, the effect of ordinary  dual-machine 3D is still not as shocking as IMAX3D, mainly due to  factors such as screen size, brightness, and the layout of the movie  theater. Because the ordinary dual-machine 3D  projection system is not like the IMAX Digital system, all aspects of  the theater are limited by a set of strict standards, so there will be a  big difference in the viewing experience of the ordinary dual-machine  3D studio. But the normal dual-machine 3D with polarized mode is still the closest approach to the IMAX 3D experience. It is also a way that the author is most optimistic and recommended.

Dolby 3D stand-alone
Dolby  3D is a 3D technology that uses a slightly different color of light to  distinguish left and right eye images. With 3D glasses with special  filter coating, it can achieve the purpose of distinguishing left and  right eye images. This principle is the same as the oldest red and blue glasses 3D, but more advanced. The  biggest advantage is that since no polarized light is used, there is no  need to use a metal screen (the role of the metal screen is to change  the polarization direction of the light after reflecting the polarized  light), thereby saving the investment in the theater. However, it is more complicated in glasses, and the glasses must be coated with a precise filter coating at a high cost. Fortunately, the glasses are still very thin and comfortable to wear. This is also the reason why the price of the Dolby 3D cinema glasses is higher after the damage.
This  type of projection also uses a 3x frame rate output similar to RealD  3D. The difference is that a color wheel with a rotation speed  synchronized with the frame rate of the projector is added to the  projector's optical path. The color wheel can pass 6 colors,  corresponding to red 1 green. 1 Blue 1 and Red 2 Green 2 Blue 2, Red 1 and Red 2 are both red but the spectra are slightly different. This allows the left and right eye images to be distinguished by proper filtering. Obviously, there are also left and right eye time differences when shooting in a single machine. However, in actual viewing, the flickering is not obvious. Although  this kind of projection method has lower cost, the disadvantages are  also obvious. The first is that the picture is darker, and because the  colors of the left and right eyes are inconsistent, the color  reproduction of the 3D picture is not accurate, and sometimes it is  sometimes brought to the eyes of some sensitive people. Come to feel uncomfortable. In general, the effect is not as good as the stand-alone projection system of RealD 3D.

Dolby 3D dual machine
Due  to the use of two projectors, the brightness will be much higher, but  there are still inherent drawbacks in color reproduction. However,  the overall viewing experience will be much better after the screen is  lit, and it is also a recommended screening method.

Xpand 3D
This technology uses active glasses to switch left and right eye images using liquid crystal lenses. Because  the glasses are heavy, the wearing is not very comfortable, and the  screen will have a strong flickering feeling due to the time-sharing  relationship. Since the active glasses need a  synchronization signal, it is generally required that the viewer's  sitting posture is relatively positive, so that the synchronization  signal can be properly accepted, otherwise the picture will lose the 3D  effect. And this type of projection is most likely to occur, crosstalk between left and right eye images. Because  there is only a single-player display, the brightness is not high. In  the end, the effect is often very poor, and the date will be more tired. It is the least recommended 3D experience.