Until recently one could only be skeptical about the existing technologies of creating a three-dimensional stereoscopic image at home. There have been but a few such products from a couple of firms. Selling at high prices, they have only been popular among a very limited number of customers. This is about to change, however, as major firms have got an interest in stereoscopy. We have recently posted a review of the 120Hz Samsung SyncMaster 2233RZ monitor and today I am going to share with you my experience of using the Nvidia GeForce 3D Vision stereo-glasses that monitor is designed to support.
Different Approaches to Stereoscopy
The principle of stereoscopic vision is simple but hard to implement on the technical level. It is only necessary to show each eye a different picture as if the eyes were looking at the object from different points of view. The rest will be constructed and calculated by the human brain.
However, it is not so simple to implement this idea. There are currently a number of various ways to show the left and right eyes different pictures and I am sure there will be more such technologies in the future.
As opposed to audio equipment, you will not achieve a stereoscopic effect if you place two monitors in front of you. The eyes both normally focus in one point of the real space, so it is hard to look at the left and right monitors with your left and right eye, respectively. Well, you can force your eyes to focus in some point of space so that the images displayed by the monitors coincided, but this method requires training and will not work at all for some people. Moreover, it strains the eyes and thus can only be used for viewing special stereoscopic pictures. You can try this method at home using pictures from the Web, for example from here (this resource also offers a brief explanation of two viewing methods). Although there are even special glasses offered for making such stereoscopic viewing easier, the method is not appealing at all. Besides, it requires as many as two monitors!
It would be logical, however, to just place two displays in front of the eyes. This is the principle that virtual reality helmets are based on. A VR-helmet includes massive glasses with small screens instead of lenses – one screen for each eye. An optical system is mounted in front of the screens to visually move the image away from the eyes – the user does not have to learn to focus his sight on the top of his own nose.
This system is ideal in separating the left- and right-eye frames because the two screens are absolutely independent from each other but such VR eyeglasses are very complex technically. The tiny screen has to have a good resolution (because the eye perceives it as a large screen viewed from a distance of 2-3 meters, so image graininess is quite conspicuous) while the electronics must be compact and light. Otherwise, the user’s neck will hurt under the load after watching a 2-hour movie or the glasses will slip down from his head under their own weight. As a result, VR glasses are expensive. You won’t even get a resolution of 640x480 for $200. And a pair of 1024x768 or higher VR-glasses will cost you a few thousand dollars. With such parameters, these devices are good for DVD-quality movies, not quite suitable for games, and totally unsuitable for office applications. They can only be interesting as an addition to a portable video player for watching movies when on a plane or something, but it is yet too early to buy one for home: junior models have low image quality whereas senior models come at an unreasonably high price.
Vuzix VR920 VR-glasses: 640x480 resolution for $400
But as there are developments in electronics and, especially, in LCD and OLED panels, VR glasses will get cheaper. Perhaps we will eventually see models with a high enough resolution (at least 1280x800 if not Full-HD) for reasonable money.
The third and far more popular method of stereoscopy is in the use of anaglyphic glasses whose lenses are color filters – red and blue, usually.
An image prepared for such glasses seems to double without them. But in the glasses each eye will see its particular picture because the red lens does not pass blue light and the blue lens does not pass red light. This is enough for the brain to construct a true 3D image.
The good point of the anaglyphic technology is in the use of one display for showing both pictures, in the rather simple preprocessing of visual content, and in the low price of the glasses. Made from a piece of cardboard and a couple of celluloid light filters, the glasses are cheap and can be even included with a cinema ticket or DVD disc without affecting the total price much. This made the anaglyphic technology widely popular in cinema houses that show 3D movies.
Of course, color accuracy suffers through the color separation of the left and right frames. Anaglyphic glasses cannot produce saturated colors because one eye does not see blue while the other eye, red. And both eyes do not see green well. Moreover, diopter correction of one of the lenses is necessary for looking at a monitor. Otherwise, the left and right eyes will see the picture in different color and focus somewhat differently, reducing the sharpness of the image. To sum up, this technology is simple but cannot reach perfection.