Instruction to see the stereoscopic applications

Warning: To see the stereoscopic applications we recommend to use at least the following resources:

- screen resolution: 1024 x 768
- video adapter: 8Mb
- processor: Pentium II or equivalent
- glasses
- BS_Contact_Stereo_70 
- Internet Explorer as browser (IE)

The first step consists in installing a VRML client that allows stereo-vision. We suggest BS_Contact_Stereo.

A free demo version of these softwares can be find in the website: http://www.bitmanagement.de/download/playerdownload.en.html

Once installed BS Contact VRML-X3D perform the following steps:
a) go to --> Windows start menu
b) select --> program
c) select --> BS Contact VRML-X3D
d) select --> Make BS Contact VRML your default viewer in IE
e) go back to the home page of the website
f) click on the virtual application
g) select one of the visualizations
h) click the right mouse button
i) select --> settings
l) select --> stereo
m) select --> red/blue
n) repeat steps i), l), m) in each open VRML window.
Note that the VRML commands of BS Contact VRML viever are attivated using the right mouse button.
Note that if you want to have Cortona as default VRML viewer you need to re-install it.

Summing up, if you are here looking for a quick and inexpensive way to view VRML worlds on a PC, here's a short summary:

1) Dowload/install the BS contact VRML client. This will allow you to fly through any vrml worlds you access through Netscape or IE (they typically have the extension *.wrl or *.wrl.gz). Their web site includes instructions on how to put their viewer into "full-screen" mode; if you have a graphics card which supports stereo (see below), this will put you into stereo mode as well;

2) Check to see if your PC has a graphics card based on the GeForce or Quadro chipset, manufactured by nVidia. If so, go to the nVidia web site and download the latest graphics driver for your system from the "Graphics Driver" menu, and the "Consumer 3D Stereo" utility from their "Games Utilities and Tools" menu. Download/install both and reboot your system. In the control panel, go to Display/Settings/Advanced/"Stereo Properties" tab and choose "enabled" and "anaglyph". Check out nVidia's how-to guide for detailed instructions on stereo viewing. One useful tip, buried in those instructions, is to use Cntrl-F5 and -F6 to adjust the convergence of the left/right images (crucial for a realistic immersive experience).

3) If you want to get full-color, shutterglass stereo, one economical choice is to buy a gamer's card from a company like ASUS. Models with "Deluxe" in the name include stereo abilities and shutterglasses, which you plug into the card. They work great with the BS contact viewer, and the ASUS stereo driver automatically gives you a nice convergence angle, for realistic-looking 3D.

Otherwise you can use economical red/blue glasses setting with right touch of the mouse select setting --> stereo --> red/blue mode

The basic trick here is to render two snapshots of the scene you wish to view, one for your left eye and one for your right. The differences between the two snapshots depend on how far away the viewed object is, and how widely spaced your eyes are, relative to the size of the object. Once you have the two snapshots, you need to deliver each of them to the proper eye.

The old technique for doing this is to produce an oversized postcard with the left eye's view on the left half in the right eye's view on the right half. A simple mechanical device then focuses each snapshot to the proper eye: the stereograph. With some training you can focus the proper image from a stereo pair on the proper eye without any mechanical assistance. Sometimes pairs are rendered with the left eye a view on the right and vice versa; the viewer then crosses his eyes to focus the proper image on the proper eye. Again, this involves some eye strain.

A second technique is to print both the left and right eye's view of a greyscale scene on top of one another, but in different colors. Such pictures are called anaglyphs. Inexpensive glasses with colored filters then screen out the left eye's picture from the right eye and vice versa.

A third technique involves projecting polarized images (different polarization for left versus right eye's view) on a polarization-preserving screen. Passive polarized glasses are then used for stereo viewing. Unlike anaglyphs, this allows full color images. New techniques involving dual, commodity-type DLP projectors (one for each eye's view) have made this approach very affordable; indeed, it has now become an attractive alternative to the shutter glass systems.

Shutter glasses are another powerful device for stereo viewing; still images and animations appear in glorious 3D color on your monitor (as noted above, passive polarized systems offer an inexpensive altenative to shutter glasses in some situations). The shutter glass approach is based on the fact that the computer, like a television set, refreshes the image on the screen many times per second. The computer alternately displays the left eye's view with the right eye's view, while the shutter glasses alternately allow just your left eye to view the screen, then just your right eye, in sync with the images displayed. The synchronization signal is sent to the glasses by wire or through an infrared emitter. If the images are alternated quickly enough (say, 120 times per second), the viewer sees a steady image in stereo. There are basically just three techniques used with shutter glasses:
Frame Flipping -
All available pixels are used to render each eye's image. This requires graphics hardware with enough memory to store both images at once.
Interleaving -
The screen alternately displays the left and right eyes images and view using, say, the even-numbered lines of pixels for the left-eye view, and the odd numbered lines of pixels for the right-eye view. This requires less graphics memory than the frame flipping approach, but results in a lower resolution image for a given monitor.
Synch Doubling -
The computer generates the left eye view on the top half of the screen, and the right eye view on the bottom half of the screen. A synch doubler then spreads out the top half image to fill the entire screen, and does the same with the bottom half image - they are alternately displayed at half the original refresh rate of the monitor. This requires no special graphics hardware within the computer itself, but again results in a lower resolution image than frame flipping. It is rather like interleaving.