SIMWEB3D Stereoscopic Image Viewing on the Web
SIMWEB3D is a utility for enabling stereoscopic image viewing on the Web with SimulEyes
glasses. Curently SIMWEB3D is implemented as a Java applet plug-in for Web browsers
like Netscape Navigator on Windows 95. The SIMWEB3D Java applet can be extended to
operate with Web browsers on other computer platforms which support interlaced video
modes and SimulEyes glasses.
Stereoscopic images are viewed through SimulEyes glasses by displaying separate left
and right perspectives to each eye. One method to present images in stereoscopic
format is to use interlaced video mode. By compositing left and right views on alternate
lines, the stereo image pair will be automatically displayed as alternating odd and
even video fields.
Stereo images which are composited in this format need only be posted on Web sites
as single image files. When presented by the Web browser, SIMWEB3D and SimulEyes'
white-line registration code insure correct stereoscopic viewing of the windowed
images.
How it Works
The trick to viewing stereoscopic images in interlaced mode is that the video card
is outputting alternate scan lines to the monitor. That is, even-numbered scan lines
(0, 2, 4...) are output to the monitor, followed by odd-numbered scan lines (1, 3,
5...) Stereo images can then be displayed by compositing a left-eye view on even lines,
and a right-eye view on odd lines. In interlaced video mode, the left- and right-eye
scan lines are output as a complete video fields as seen through 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 properly in sync with left and right eye views. (Under Windows 95, events
may take place where the system taskbar "re-draws" itself to partially obscure the white
line code. If this happens, you may need to drag the taskbar 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). If not accounted for, 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 right eye sees the left-eye's view.
This phenomenon called "psuedo-stereo" contains depth information as in the correct stereo orientation. An observer will have a more difficult time perceiving depth,
or not at all, and overall the perception just "doesn't look right".
The function of the SIMWEB3D applet is to control a separate window from the Web browser.
That way a user may drag the window anywhere on the desktop, and the window will
always be insured to align to appropriate scan line for correct stereoscopic viewing. For example, if the user happens to move the window to an odd line, then the window
will re-move itself to the next even line. (Note Netscape Navigator 2.x users will
not be able to move the Java applet windows.)
SimulEyes drivers
The SIMWEB3D applet needs to activate a platform-specific SimulEyes driver into an
interlaced video mode and paints the SimulEyes white line code at the bottom of the
display screen. The SimulEyes driver for Windows 95 is called SVR3D32.DLL, and must
be present in the Window System directory, C:\WINDOWS\SYSTEM.
The SimulEyes Windows 95 drivers can select interlaced modes only for specific chipsets
in 256-color modes at 1024x768 resolution. Chipsets have been selected based on popularity,
like S3, Cirrus Logic, ATI, and others are added whenever possible in the form of a replacement driver DLL. In the future, VESA interlaced modes will become standardized
as part of Windows.
In the event that the user has a video card which is not supported yet by the SimulEyes
driver, the user may be able to manully set the video mode to interlaced through
the Windows Control Panel for Display Settings. If this is the case, then the driver
can still be used to draw the white-line registration code at the bottom of the display
to activate SimulEyes glasses.
Availability
The SIMWEB3D applet is available for downloading from our ftp site.
ftp://ftp.stereographics.com/java/simweb3d.zip
Stereo images in SimulEyes-ready interlaced format are currently posted at these
sites:
ftp://ftp.stereographics.com/java/stereo.html
http://www.concentric.net/~bruced
For further questions, contact
se-supt@crystaleye.com