Using SG-Toggle for Stereoscopic Image Viewing

SG-Toggle is a simple Windows desktop accessory for enabling and disabling stereo  image
viewing with SimulEyestm glasses. SG-Toggle is available for Windows 3.1 and Windows 95. 

Each version of SG-Toggle activates a SimulEyes Windows driver which sets the monitor into
interlaced  video mode and paints the SimulEyes white line code at the bottom of the screen.  The
white line code is used to trigger the shutters in SimulEyes.  The SimulEyes driver is called
SVR3D.DLL for Windows 3.1 or SVR3D32.DLL for  Windows 95.  These drivers are included
in the ZIP file with SG-Toggle. Either of these DLL drivers must be present in the same working
directory as SG-Toggle  (or copied into the Windows System directory, C:\WINDOWS\SYSTEM).

The SimulEyes drivers for Windows work only for specific chipsets in 256-color modes of
800x600 or 1024x768 resolution. Currently, we support the most popular chipsets and continue
to add support for other chipsets.  As this support is added, you need only replace your current
DLL with the newer versions we will post. (In the future, VESA interlaced modes will become
standardized as part of Windows.)

In the event that your video card is not yet supported by the SVR3D driver, SG-Toggle will
generate an error message.  However, in some cases, you may be able to manually set the video
mode to interlaced through the Windows Control Panel under Display Settings. If this is the case,
then SG-Toggle can still be used to draw the SimulEyes white line code at the bottom of the
display thus enabling stereo image viewing.

Interlaced mode works by first drawing the even-numbered scan lines (0, 2, 4 . . .) on the monitor,
then returning to the top to draw the odd-numbered lines.  The method for viewing stereoscopic
images in interlaced mode is to output left-eye images on the even-numbered scan lines, then the
right-eye images on the odd-numbered scan lines.  In interlaced video mode, the left- and 
right-eye scan lines appear as complete video fields alternating left and right in sync with the
SimulEyes' shutters.

When interlaced video mode is active, white line code also needs to be drawn at the bottom of the
display. This white line code is the registration signal for shuttering SimulEyes in sync with left-
and right-eye views. (Under Windows 95, if your taskbar is displayed at the bottom of the screen,
you may need to move it to another side of the display.)

Stereo images are properly composited when the left-eye view begins as the first even scan line
(or multiple of an even scan line). There is a 50/50 possibility for displaying  the composited
stereo image improperly in a window on the desktop. That is, if the window is positioned or
re-sized such that the left-eye information effectively begins on an odd scan line, then the stereo
information will be inverted. This phenomenon, called "pseudo-stereo", may appear to contain
depth but the observer will have a more difficult time perceiving depth, or not at all, and the
overall perception won't be correct.

To remedy this problem, a registration test image is necessary to initially align a window on the
desktop for use with SG-Toggle.  We have included a test image called TEST.GIF for this
purpose.

Currently under development is a Windows utility which automatically compensates for correct
window positioning. In cases where the left-eye information starts on odd numbered lines instead
of even, the white line code is reversed to match.  This keeps the overall stereo image in the
correct viewing orientation.  This utility called SIM3D is being developed as a Java applet for
viewing stereo images with Windows 95 web browsers like Netscape.  Registered developers can
get this utility by contacting the StereoGraphicsDeveloper Program.

Images in SimulEyes-compatible interlaced format are currently posted at these web sites:

http://www.3d-web.com
http://www.dnai.com/~threed
http://www.community.net/~bad
http://synergy.exploratorium.edu/ceder

For further questions, contact SimulEyes support.


