Stereo3D Technology Explained
But first a question .. what do you think when you read about this particular topic called 'stereo'?
A new Dolby Digital feature?
Another new feature like FSAA or TileBasedRendering?
Let us make it a little paradox and need to forget instantly as this is what it is NOT.
The term Stereo3D means nothing less than to bring the third dimension to your 3d games and applications for real. To understand what exactly you experience when you put on those goggles you need to understand the technology and what it does to the brain.
Stereo technology is adding that other dimension of realism to the brain. Face it, we all want to be in a 'virtual reality', would it be good to play Tomb Raider with the optical illusion you are in that 3D scene ? This is what the technology is about and exactly what it is trying to do.
The idea of stereoscopy is nothing new, it was always a wish of the consumer to not only have 2-dimensional pictures, but to keep a kind of 3rd dimension, to make pictures look more realistic.
Back in the 19th century, when the first photographers were made, the people began to think about stereoscopic pictures.
So they developed stereo cameras and viewers. At this link for example you can find photographers dated at 1886.
The idea is based on the humans biology:
We have 2 eyes which both deliver 2 slightly different pictures of the same situation. The further an object is away, the less these 2 pictures will differ and the other way round, the nearer an object, the more different these two pictures will be.
So the only thing we need is some hardware (a stereo viewer, 3d glasses, ... whatever) that gives us these two "slightly different pictures". Take a good look at the image below:
This figure gives a good example,
how the 2 pictures get combined in our brain.
Stereo3D on the pc - main differences
True "holographic" systems (like in StarTrek or Perry Rhodan stories) to show you Stereo don't exist yet (or are at least not available to the public, who knows).
Today the most common way of bringing Stereo to the pc (or the TV) is based on this idea:
The usual monitors of today will display two different pictures: one for the right and one for the left eye.
These two pictures must show the situation from slightly different positions, just like it is in reality.
So in addition to new software (Stereo driver) you will need some kind of hardware (e.g. Stereoglasses).
Now let us take a look at some 3D Stereo technologies for the PC as there are several platforms to choose from :
(no name anaglyphic glasses)
These are based on the idea of splitting an image into 2 pictures by taking only the red colors of a picture for the left and the green color for the right eye. (It is also common to use other colors, like blue or yellow)
Second, as you can see at the screenshot below, both sub pictures show the scene from different perspectives.
Third, both sub pictures are overlaid, drawn at the monitor at the same time, so the picture you see in the screenshot does show exactly how the displayed picture on the monitor will look like.
At this place you can try to get anaglyphic glasses for free.
Generally they cost about $1. (you also make your own of course). This however is not a preferred technology for the PC and especially PC gaming.
- LCD Shutterglasses
Stereo3D with shutterglasses is realized in the way that 50% of the number of rendered pictures will be used for the left, and the other 50% for the right eye. The technique called "time-sequential multiplexing" will then alternately display left- and right-eye images every time the computer refreshes (draws) the screen.
Synchronized to these altering images the shutterglasses will work. They have 2 LCDs, one directly in front of each eye. Each LCD can block one eye's view onto the screen. When an image for the left eye is drawn on the monitor, the LCD of the right eye will block the right eye's view and the other way round.
If this is repeated fast enough (faster than can be perceived), and if the synchronization can be kept, then this will make you think you're seeing true 3D.
The price for technology like this is relatively cheap: $15 up to $200. Tip: of course you can also get used ones at eBay...
It is a bit difficult to show you a picture on how this would look on your monitor because both kinds of pictures are not drawn overlayed.
There are several techniques that can be used by shutterglasses (Page-Flipping, Line-Blanking, Interlacing, Sync-Doubling) which will not be reflected here.
(This is the "hi-Res 800" from Cybermind)
I think this is what you might have expected as "Virtual Relity Device" (in contrast to the 3d-glasses).
These helmets have 2 small screens (most common used are TFTs/LCDs) in front of the eyes: one for the left and one for the right. By showing (you might have expected that) 2 slightly different pictures on each monitor, the user will experience a 3D feeling.
This is a very expensive method. VR-Helmets mostly are expensive hardware thus making them only affordable for professional users and not us gamers - but prices are dropping, you can get the "hi-Res 900" for about $3000 for example.
- True 3D Displays - The most beautiful technology of them all is true Stereo without additional hardware on that head of yours.
(Dresden3D's 'D4D' 18.1" 3D-display)
These autostereoscopic devices also use the way to show the eyes two different pictures, but this is done in a completely different way. There is a very nice video that shows you how it works in a simple and understandable way: Click here.
Over at Stereo3D.com you can find a review on that device.
The vertically interlaced stereo-image goes through a prism-mask which is aligned according to the users position provided by an eye-tracker on top of the screen. In later versions the eye-tracker will also be used to allow some limited headtracking for looking around objects.
The price of these devices are...ehm... high. Very high.
Conclusion - to use or not to use?
The most interesting techniques for gamers are the anaglyphic and shutterglasses.
Shutterglasses have one main disadvantage: the so-called "ghost effect". Even though the LCD should block one eye's view on the monitor you can see "ghost images" of the monitor. This can be caused by either the LCD not blocking the view 100% but perhaps 95%, so that 5% of the light that is sent out by your monitor can reach your "blocked" eye. Or the LCD does not block your view fast enough, so that the wrong eye can see the image on the monitor for a short time. If this ghost effect takes overhand then the whole stereo feeling gets messed up. So it's the manufacturers task to keep the ghost effect non-existent.
Anaglyphic glasses are ultra cheap, sometimes you even can get them for free with several magazines. But in most cases you will see the application in wrong colors.
I think the other two stereo techniques are not comparable here.
Both the VR-Helmets and the 3D-displays are very expensive.
They are something for CAD works and the military (esp. VR-Helmets in this case).
Even though it would be a great thing to have one of these two for gaming, there's another problem: Generally VR Helmets and 3D Displays do not have global Direct3D or OpenGL support, which makes it difficult to play games at the pc :)
But without any doubt, the VR-Helmets would give you the most realistic 3d experience (because your whole field of view is covered by the 2 displays).
Recommendations - I don't want to recommend you the anaglyphic or the shutterglasses, I recommend to try both of them if you want to experience Stereo3D.
VR-Helmets and 3D displays are too expensive and don't support today's games, so better wait some years, perhaps one day somebody writes a unified Stereo driver for all kinds of stereo techniques...
"To stereo or not to stereo" - There has been a lot of discussion about the question if stereo gaming really is that great as it is advertised.
This question is difficult to answer because several people swear they'd never had such a great multimedia experience, other say they're very disappointed about it.
A main fact to know is, the better your pc hardware, the better you can experience the stereo effect.
With a tiny 500MHz processor and perhaps a 15'' monitor at 85Hz your stereo will be at a lousy quality as well as lousy performing.
Hint - You already have stereoglasses? Then you should try this:
Download the Dreamrender Desktop3D, this uses Direct3D to display your Windows desktop...and since the Stereo driver can be turned on with all Direct3D applications you can experience your desktop in Stereo3D!!