by Oleg Artamonov
04/13/2009 | 01:20 PM
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.
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.
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.
The glasses are shipped in a medium-size box painted Nvidia’s corporate colors. You can see the left part of the device through the transparent window. It looks like regular glasses with a large frame.
The box has an original folding design. Opening it up, you can find a pair of 3D glasses, a transmitter for synchronizing them with a computer, and a set of replaceable caps for the tips of the frame.
The glasses have a normal design and you can even wear them outside without being made fun of. The sides are rather too wide, but you can hardly suspect the glasses to have any electronics at first sight. When turned off, the lenses let pass about half the light, but I don’t recommend you to use your GeForce 3D Vision as sunglasses. Direct sunlight is harmful for the liquid crystals the lenses are made from. For you not to forget to take the glasses off before going out, they are equipped with a protective mechanism: the lenses begin to blink after a while when you don’t use the glasses.
All the electronics is located in the small excrescence on the inner left side. The glasses do not require a wire connection when working. They are powered by an integrated lithium-ion battery and receive the sync signal from the IR transmitter.
An On/Off button and a Power/Battery indicator are located on the top of the frame. The glasses shut down automatically after a few minutes of being idle. They blink with the lenses before doing that in order to remind you that you should take them off.
A standard mini-USB connector is used for recharging the battery. Theoretically, this interface might be used to update the device’s firmware, but Nvidia’s folks have told me that the firmware won’t be updated unless really necessary. Recharging takes 3 hours. The battery life is specified to be 40 hours (I did not have an opportunity to check this out myself).
The glasses are light. Its electronics does not feel as a weight when you wear them. An obvious disadvantage is that you cannot combine them with ordinary glasses for eyesight correction. The passive polarizing glasses from Zalman and iZ3D can be designed as clip-on lenses, but Nvidia’s glasses require a frame with electronics.
This problem can be partially solved by the nose pads included into the kit (three pads of different sizes). I wore them together with my ordinary glasses when using the GeForce 3D Vision and did not find them to be much uncomfortable, yet I did think about contact lenses.
The 3D glasses must be synchronized with the computer to dim the left or right lens simultaneously with the monitor’s change of the frames. This is done by means of an infrared transmitter that is guaranteed to work at a distance of 5 meters. It looks like a small black plastic pyramid. The transmitter must be located in direct view of the glasses.
The computer and glasses have a unidirectional connection, so you can use as many 3D glasses as you want with only one transmitter – all of the glasses will receive the same signal. It is yet impossible to buy the glasses apart from the transmitter, but Nvidia has promised to provide this opportunity in the future.
The transmitter has a mini-USB connector for connecting to the computer, a 3D Sync In socket for TV-sets that support GeForce 3D Vision technology (Mitsubishi’s DLP models are listed as such; you don’t need this socket when using the glasses with an ordinary monitor), and a wheel for on-the-fly adjustment of 3D depth. Although you can change various parameters, including the depth of 3D space, with hot buttons, the wheel is handier: you don’t have to remember the hot buttons, and the latter may not work in some games.
The GeForce 3D Vision needs an LCD monitor that supports a refresh rate of 120Hz (there are two such models available as yet: Samsung SyncMaster 2233RZ and ViewSonic VX2265wm), a DLP TV-set from Mitsubishi (the model list is available at Nvidia’s website), other 3D-ready DLP TV-sets or a DepthQ projector. I have little doubt that the list of compatible display equipment will get much longer in the following months, and this is one of the strong aspects of the GeForce 3D Vision technology.
Unfortunately, many modern LCD TV-sets that are specified to have a refresh rate of 120Hz can only receive 60 frames per second from a computer and are not compatible with the GeForce 3D Vision as the consequence. Hopefully, this drawback will be soon corrected by the manufacturers. At least, they’ve got a good incentive to do that now.
The stereoscopic technology is compatible with all more or less advanced gaming graphics cards from Nvidia, starting from the 8800 GT and 9600 GT. This is because you won’t be able to get enough speed on weaker graphics cards – the graphics load grows twofold when you enable stereo mode. Both single- and dual-chip cards are supported including SLI configurations with two cards.
There are no other critical hardware requirements.
The GeForce 3D Vision comes with an individual stereo driver that is currently version 182.46. The driver is meant for Windows Vista. Windows XP is not supported officially. The driver works in both 32-bit and 64-bit versions of the OS.
Currently 3D applications can work with the glasses in full screen mode only but Nvidia has promised to extend such support to windowed mode.
When the driver is installed, Nvidia’s Control Panel acquires a new tab for the stereoscopic mode. There you can set the depth of the 3D space (which can also be adjusted by the wheel on the IR-transmitter) and select the monitor to use. The driver also supports anaglyphic glasses I described at the beginning of the review. Of course, you don’t need a 120Hz monitor for such glasses.
You can change the stereo mode settings within a game by means of hot buttons. If the 3D space looks uncomfortable or you have problems focusing your eyes or moving them between the objects, or your eyes feel tired in 15-20 minutes of play, you should try to adjust the settings.
You can enable a laser sight in the supported games. The ordinary sight usually does not work well with a true 3D picture and can be anywhere when you turn the stereoscopic mode on, making it hard to aim accurately.
The list of officially supported games can be found in a separate window. The quality of the stereo effect is indicated in a three-value scale, and there are comments for some specific games. If a game is not on the list, you can still try to use the stereo mode in it. It just has not yet been tested and evaluated by Nvidia.
Nvidia being one of the two major GPU makers, I hope that game developers will surely take the stereo technology into consideration while working on their new projects.
So far, the quality of this mode depends on how correctly the distances and proportions of the 3D scene are implemented in the specific game.
Games based on the Source engine (developed by Valve Software) and Cry Engine (by Crytek) have a correct 3D scene. The effect is impressive in Left 4 Dead as the buildings, objects and characters all become so real that you want to reach out and touch them. As a single drawback, there were odd artifacts in bright spots of light when I was walking with a flashlight.
There was an odd effect in Prince of Persia. Although this game has the highest compatibility level in Nvidia’s list, I did not feel much of stereoscopy in it because of the specific contours around the characters. The brain perceives the characters as just drawn rather than three-dimensional. You can focus on the picture to see the third dimension, but as soon as you relax, the game world becomes flat again.
The perception of the stereo mode in strategies depends on the specific game, too. If there are some labels attached to the units (for example, labels showing the unit size in Heroes of Might and Magic), they prove to be hanging somewhere between you and the unit, which is inconvenient. The game developer obviously did not think of any stereo modes and did not assign a specific depth for such labels. If there is nothing like that in the game, the game world looks just splendid. You get a feeling that there is a tiny real world in front of you, with tiny factories and tiny tanks. Sometimes I caught myself wanting just to take a tank with my fingers and move it on the map where it was needed.
I did not notice any doubling or ghosting of the image resulting from the left eye seeing the residue of the right-eye image (this effect could be seen on the iZ3D monitor and was really irritating).
It is assumed that the lenses in shutter glasses are switched alternately. When one becomes transparent, the other is opaque, and vice versa. Such a swift switching is no problem for the simple liquid-crystal shutters, but may be a problem for LCD monitors. As I found in my test, the 120Hz SyncMaster 2233RZ took an average 3 milliseconds to switch between halftones. It means that if the lenses switched instantaneously, one eye would see the fading-out remains of the picture meant for the other eye for an average of 3 milliseconds. And there are also RTC artifacts that take even more time to disappear.
To check out Nvidia’s solution of the problem I measured the process of lens switching by placing a photo sensor connected to an oscilloscope on one side of it and a light source on the other side of the lens. The high level of signal in the oscillogram corresponds to the period of time when the lens is translucent.
As you can see, the lens is translucent only 2 milliseconds out of each 16.7 milliseconds. That is, most of the time both lenses of the 3D glasses are shut and the monitor has 6.3 milliseconds (because the frames go at a rate of 120Hz, i.e. one frame each 8.3 milliseconds) to change the picture.
Unfortunately, such a low on-off time ratio (with a short period of translucence and a long period of opaqueness) leads to a 60Hz flicker. The perception of the flicker depends on the particular person. Some people may take no notice of it while others will have sore eyes, but the flicker is indeed perceptible.
Flickering is less conspicuous in dynamic visual content such as games and movies (we watch CRT TV-sets at 50Hz, for example), and the glasses turn off when you leave a 3D application. Here, in our labs, the opinions differed. I could see the flickering well enough as soon as I looked away from the monitor at a light wall and sometimes noticed it in games, but my colleague did not see any flicker at all.
To reduce the flicker, Nvidia recommends setting the maximum brightness on your monitor in games (the backlight lamps do not flicker then, which can save you from possible pulsations of brightness due to the overlapping of the two frequencies) and try to avoid daylight lamps with electromagnetic ballast that flicker at the double frequency of the mains.
Besides, the glasses reduce the intensity of light greatly, making the surroundings dim. Therefore the monitor must have a good brightness. The SyncMaster 2233RZ ensures over 300 nits, however, so this was not a problem. The glasses reduce the brightness of the ambient light, too. So you can play normally even under good daylight.
Nvidia’s 3D glasses do not have a negative effect on the monitor’s color reproduction or viewing angles.
The main reason why I have nearly no doubt about the future success of the GeForce 3D Vision glasses is that they are compatible with graphics cards and monitors from different manufacturers. As opposed to the competing technologies such as Zalman Trimon and iZ3D, you don’t have to compromise, choosing a monitor out of two models that only differ with screen size and have unassuming exterior design. Even today, the two major monitor makers Samsung and ViewSonic have provided GeForce 3D Vision compatible products. It means that Nvidia has found an understanding among first-tier manufacturers and we will surely see such monitors from other brands, especially as there is nothing technically complex about them.
And contrary to the products from Zalman and iZ3D, you don’t even have to buy such a monitor especially for stereo glasses. As you know from our previous review, the Samsung SyncMaster 2233RZ is quite an interesting monitor in itself for gamers as well as ordinary users. Besides the compatibility with stereo glasses, its 120Hz refresh rate ensures excellent smoothness of motion and considerably reduced visual artifacts together with a fast response time.
So, it is quite possible that in a few years many users will use GeForce 3D Vision compatible monitors without any stereoscopic glasses. It’s like with sound controllers that are currently integrated into every mainboard. You may not think about sound when purchasing a mainboard. But when you need to listen to music later on, you will only have to plug your speakers in. And the speaker set maker sells only speakers rather than some “hardware-based music playback system” that would make you upgrade/replace half of your computer.
And finally, the GeForce 3D Vision is compatible not only with monitors but also with TV-sets and even projectors. Although there are few such models available today, the manufacturers will be able to introduce stereo mode support quite easily. 120Hz LCD monitors have been produced for a long while already, and it only takes a small modernization of their electronics. Just imagine a true 3D picture on a 40- or 50-inch screen – what competing technology could match it?
The stereoscopic glasses are only available from Nvidia today, but it is not this company’s policy to promote ready-made solutions under its own brand. Therefore, I guess that the production and sales of the glasses will be offered to third parties for a licensing fee.
As for the quality of stereo mode support in different games, Nvidia’s position in the gaming world makes me optimistic. The company has an influence on game developers and experience of collaborating with them.
And what about the price factor? Well, the recommended price of the glasses is $200. A 22-inch monitor from Samsung will cost $400 more. This is about the same money as you are asked to pay for the competing products from iZ3D and Zalman but the latter are obviously inferior in their monitors’ exterior design and setup quality. So, Nvidia does not look advantageous in one case only: if you want to buy a few pairs of glasses. Even when the 3D glasses begin to sell apart from the transmitter, they will hardly be priced lower than $150.