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Polarizing glasses is yet another image separation method. Human eyes are not sensitive to light polarization, so if one and the same display device is used to simultaneously show pictures for the left and right eyes with different polarization and if you wear glasses with differently oriented polarizers instead of lenses, your eyes won’t notice anything wrong, but will see each its own picture. Polarizers are rather cheap, so the glasses are about as cheap as anaglyphic glasses but do not affect color reproduction.

It is rather easy to produce visual content for such glasses in a cinema house. You take two projectors working simultaneously with polarizers in front of each. And there is a metallized screen that does not change the polarization of the reflected light. One projector is displaying a film with the visual content for the left eye and the other projector, for the right eye. The visitors put on the provided eyeglasses and watch a 3D movie. This is the technology employed at IMAX movie theaters.

It is, however, problematic to use this technology at home because one projector is already quite a costly thing. Therefore the developers have to invent some other ways of utilizing light polarization. Two methods have already been discussed in our earlier reviews.

Zalman is offering Trimon series monitors that have a special film over the screen that makes the odd and even-numbered lines of the screen have different polarization. As a result, if you put on polarizing glasses, your left eye will see some lines while your right eye will see the other lines. Then, it is only necessary to produce two interleaved pictures and show them simultaneously in order to produce the stereoscopic effect.

The highs of this technology are obvious: cheap glasses (which means you can buy a few pairs to watch movies with all your family), normal color reproduction, reasonable price of the whole system, and the opportunity to use the same monitor for everyday work. Alas, Zalman did not manage to make its Trimon suitable for the latter application. When in 2D mode the Trimon is an ordinary 1680x1050 monitor but the additional polarizing film is quite visible: the screen seems to be crossed with thin horizontal lines, which doesn’t look nice. Moreover, the monitor works at only half the vertical resolution in 3D mode (each eye sees a 1680x525 picture) while the viewing angles are rather limited.

And most importantly, this technology is Zalman’s property. So far you can only choose one of two available models differing in screen size. And the Trimon series monitors are far from perfect in terms of design and setup, which is quite a serious drawback, too.

The developers from iZ3D offer another version of this technology: a monitor with two sandwich-like matrixes. The bottom matrix produces the combined picture for both left and right eyes while the top, simpler, matrix rotates the polarization plane, to give each eye the necessary share of light. The iZ3D monitor must be used with a pair of cheap passive glasses with polarizers.

As opposed to Zalman’s Trimon, the iZ3D works at full 1680x1050 resolution in each mode. It does not have horizontal lines on the screen and its viewing angles are considerably wider. Therefore I thought it a more promising technology than the Trimon. However, the iZ3D has drawbacks of its own. The manufacturing cost of such monitors is high due to the double matrix, and the second matrix worsens image sharpness in 2D mode a little. And most importantly, this technology is only supported by two models manufactured by one firm, making your shopping choice very limited.

Thus, one of the most important drawbacks of the stereoscopic monitors from Zalman and iZ3D is of the marketing rather than technical nature. Choosing one of these technologies, you will have to buy a monitor from the corresponding firm irrespective of whether you like it or not. Considering the unassuming design and low setup quality of the products from both companies, it means you face the choice between playing games in true 3D and working at a really good monitor.

But even back at the end of the last century there was a technology that could produce a high-quality stereoscopic picture on almost any monitor. Its most well-known implementation was the 3D Revelator eyeglasses from ELSA that had liquid-crystal shutters instead of lenses. The shutters could change their opaqueness, getting darker or lighter as commanded.

The point of the technology is simple enough. The monitor is working with a refresh rate of 120Hz, outputting frames for the left and right eyes alternately. Then, the user can put on the LC-shutter glasses whose shutters are closed alternately. As a result, each eye will see 60 frames per second.

Being the most notable implementation, the ELSA 3D Revelator did not really take off. This device was unhandy and had a lot of hardware and software problems. It did not support the then-popular 3D accelerators from 3dfx and were officially meant for video cards made by ELSA itself.

In the following years this technology was almost forgotten. CRT monitors died out like dinosaurs (they did have something in common in terms of size and weight) whereas new LCD monitors could not support a refresh rate higher than 60Hz. (each eye would only see a refresh rate of 30Hz in the LC-shutter glasses, which resulted in a strong flicker).

This situation has changed but recently. LCD monitors have evolved, making it possible to use a refresh rate of 120Hz. In a recent review I have discussed the 120Hz Samsung SyncMaster 2233RZ model and liked it very much.

Today, I will describe the new LC-shutter eyeglasses from Nvidia which are to be used with 120Hz monitors and GeForce graphics cards. But as opposed to the technologies from Zalman, iZ3D and ELSA, these can be any 120Hz monitors and any graphics cards with Nvidia GPUs.

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