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Double your refresh, double your fun

Posted by Jon Peddie on January 9th 2009 | Discuss
Categories: Hardware Review
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The stereopsis experience

To get a flicker-free stereoscopic image, you have to have 120 Hz refresh with a single screen, and it doesn’t matter if it’s a single LCD, plasma, DLP, ventricular display, or a CRT. Anything less is a compromise that will cause eye fatigue and send you away, probably not to return.

So, as CRTs faded from the desktop of gamers, and too few had a high-speed DLP projector, the concept of stereovision for games languished, with the notable exception of IZ3D’s dual-plane LCD design. In addition to IZ3D, Zalman has offered a custom display which offers a passive solution.

Then, you have to trick your eyes into seeing alternative images. That’s typically done with glasses, or with prisms.

And when it’s done correctly it’s called stereopsis (from stereo meaning solidity, and opsis meaning vision or sight). And it produces the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. It’s the different perspectives of our two eyes that lead to slight relative displacements of objects (disparities) in the two monocular views of scene. And that makes it possible for most of us to use these disparities for depth-estimation, and to merge both monocular views into a fused cyclopean view of the scene—this is done in the brain, not the optical pluming. However, correct and fast estimation of disparities is a difficult problem. Besides disparities, various additional image variations occur between the left and right view of a scene. Differences might be caused by occlusions of objects, specular reflections, which move independently of the surfaces of objects, sensor noise, and various other causes and, in the case of a synthetically generated scene, views of objects that don’t exist.

Experiments have gone on for over two and half decades in computer generated stereopsis, and the reason that’s true is because no one has really come up with a foolproof means of tricking our eyes and brain into believing the images generated on a flat 2D screen really represent a scene with depth—but boy-oh-boy are we getting close.

By far the most successful technique to date has been shutter glasses. They have, and are used in CAD, molecular modeling, subterranean geophysical examination, medical diagnosis, airfoil analysis, design and style reviews, and battle scene management to name a few applications. And now, with the introduction of LCD monitors that can refresh 120 times a second, shutter glasses can be applied to 3D FPS games—3D in 3D, yessirree.

Nvidia’s GeForce 3D Vision

Just before the holidays, we were able to get our hands on a new 22-inch 120 Hz Samsung 2233RZ monitor and Nvidia’s shutter glasses and transmitter. Nvidia first showed this rig as a prototype at the Nvision conference in San Jose in late August, and it was an instant hit even in its prototype form. Since then, the company has gone into production on the glasses and the IR transmitter, special divers, and the evaluation and testing of hundreds of games. This is, in typical Nvidia fashion, a complete product and maybe one of the company’s first truly consumer products that you will be able to find at retail outlets as well as online.

Physics yes, SLI?

We installed 3D Vision on a Nehalem system with three Nvidia AIBs in SLI running 64-bit Vista, and there was no indication that SLI was being used. However, the 3D Vision drivers control panel does indicate that PhysX is enabled. Nvidia says GeForce 3D Vision supports any single- or dual-GPU SLI configuration.

Nvidia says that, given the fact that three-way and Quad-SLI configurations are not currently supported, you would need to remove one GPU (and appropriate SLI bridge) to have GeForce 3D Vision work correctly. Also, not all GPUs can be used—only the big 8800s (Ultra, GTX, GTS, and GT), or the big 9800s, and all of the GTX 200 series AIBs.

The first thing you have to do is to unload the current Nvidia driver, which, in our case, was the latest one used for benchmarking. Then the setup is pretty straightforward: load the driver, plug in the transmitter, put on the glasses, do some on-screen checks to make sure things (and you) are working correctly, and then, let the games begin.

The shutter glasses are stylish, with a hint of Nvidia green at the tips, and a mini USB connector for battery recharging. The shutters are very fast (<5ms) so there’s no ghosting due to them (ghosting is when portions of the left image are seen with the right eye) and they are reasonably lightweight, no heaver than a pair of sun glasses, and probably lighter than a pair of prescription glasses. Because they are just shutters, they are not resolution-dependent.

Opening up the Nvidia control panel, we looked in the “compatible games” list. It’s quite long—over a couple of hundred games. Nvidia says GeForce 3D Vision uses game profiles similar to their SLI profiles and that’s why they have so many games. So we clicked on “Show only installed games.” I didn’t see Call of Duty World at War, but it was in the larger list, so I selected it from the large list. The control panel gives you advice about the game, including how playable it is.

So we tried about a half dozen games, specifically: Bioshock, Call of Duty World at War, Crysis Warhead, Fallout 3, FarCry2, Spore, and Stalker Clear Sky. We had different experiences with each game, most of it good, some of it annoying—FarCry2 being the most difficult—the results are very much game-dependent and setup-dependent.

The glasses are controlled by a small IR transmitter. When a game is loaded that is recognized by the driver (from the list shown above) the transmitter’s green light comes on. To get the glasses synched up, you press a small unobtrusive button at the top of the frame, and when there is a link, a small green light at the top of the frame lights up.

While you are playing games, the field of view of the IR sensor is quite wide and can be almost anywhere.

When you start a game, some hints about how to set it up appear on the lower right-hand corner of the screen.

I started out with Call of Duty World at War and it was an interesting and exciting experience. However, after about 30 minutes I found the glasses to be annoying, felt a little nauseous, and decided to switch games. Later I learned that I missed the importance of the dial in the back of the IR transmitter, which can adjust the depth of view. That makes all the difference in the world in terms of eye strain and image quality. However, in playing the game I noticed a few places where the image was not resolved and/or had a shimmer to it which preventing seeing it—bad when in a fire fight.

Next, I tried Fallout 3. It ran well but the sighting for firing the weapons was unreliable, so I had to shoot to the left and right and hope to make a hit. Fallout 3 is a console game modified for the PC and has arcade-like qualities to it. Enemies take five to 10 hits before they go down. With inaccurate sighting, it can take more shots (depleting ammo). However, the imagery looked excellent. Adjusting the depth helps get the gun sights lined up with where the shot goes. The stars in the night scenes seemed to float in front of me.

Stalker Clear Sky offers five types of rendering: enhanced full dynamic lighting, DX10 dynamic lighting, object lighting, full dynamic lighting, and static lighting. The stereo view only works with static lighting. You cannot get a stable image using the other modes but not much is lost using static lighting.

Spore has simple 3D models, almost no lighting, some shadows, and no reflections. It is a game designed to play on almost any platform. With that said, it ran fine in stereo and did provide some enhancement to the game. However, the moons are not in the background and float out in the scene, regardless of the depth setting dialed in.

Bioshock, as always, was a pleasure. The depth had to be turned all the way down and almost all rendering features muted, but it played well and the stereo did make it more interesting.

In the case of Crysis Warhead, The cursor position on the startup menus are way offset so you have to go hunting around the screen to get the game started. I never did find out how to access the controls for setting resolution and other parameters. On some screens, there are two small red circles next to each other which can (depending upon the screen) represent the cursor’s active area.

Inside the game, fire looks like it’s floating in space, and the image is highly pixilated and has left-right jitter when moving. It’s good when stationary. It’s not easy or fun to play.

I tried it with the glasses and sensor disconnected to see if I could get the game setup, and it still behaved poorly, shaking right and left at about 5-10 Hz, I couldn’t get full-screen operation.

I Loaded FarCry 2 and it was extremely slow and unplayable. I uninstalled, reloaded, and got it to run—but not full screen—even though 1680 x 1050 res was selected. 3D Vision never sensed the program. I uninstalled and, after removing one of the AIBs, reinstalled and then downloaded an upgrade from Ubisoft. Then things started to work, and work very well, stereo vision really made a difference in the game play.

What do we think?

It’s really game dependent and it will take a while (like a year or two) before the game developers get proper stereo built into games. In the mean time, Nvidia will continue to offer patches and hope for the best. Overall, we had a favorable to very favorable reaction to Nvidia’s 3D Vision.

The 22-inch 120 Hz monitor, which is otherwise unremarkable, will sell for around $399 at retail. Other companies, like LG, Viewsonic, and, Mitsubishi are expected to join the market and 120 Hz will eventually become the standard.

This is clearly going to be the new way games are played. The investment isn’t too high, and will come down over time. The early game patches look good and give “good enough” to great results. The game developers will now seek differentiation on how well their stereo is—YAF—yet another feature, like adding on-line capability, they’ll have to provide.

Epilog—stereo benchmark

One thing that is clear (no pun) from all this is that there has to be, and I predict soon will be, a stereovision benchmark. That’s going to be difficult. Of course, frame rate can be measured in stereo mode, that’s easy. But coming up with an objective analysis of the picture quality is the same problem you have with video—different eyes see different things in an image. We might be able to put up a test scene and measure the depth of elements in it, but how do we measure ghosting and stereo rectification that tries to create warps of images where no information existed before the stereopsis? That will be difficult, and yet it must be done if we are to have some sense of what to expect in the products we’ll buy for stereovision.