3. Set Up Procedure The system requirements were described in this page. Connect your monitors, keyboard, mouse and splitters. Make sure that Twinview (i.e. the graphics card has two outputs)works and for now set up the desktop for horizontal span (described below in Section 3.1.1). Applications for the Geowall require either 'Clone mode ' or 'Horizontal span' on the graphics output. 3.1.1 Set up Display Modes Here is a brief description on how to get horizontal span on Windows and Linux for the Nvidia cards. Windows 2000/XP:
3. Click OK. Linux: 1. The /etc/X11/XF86Config-4 file controls how the display should look. Please look at the README file that Nvidia provides. The following is a chunk out of this file relevant to setting up Twinview. Section "Screen" Subsection "Display" Option "TwinView" EndSection You can download an example XF86Config-4 file here. This file is configured to run in 'Clone mode' where both your monitors will show the same desktop instead of the desktop being stretched across. Change the 'TwinViewOrientation' to 'RightOf' (or 'LeftOf') ; restart the Xserver and you should see the desktop stretch across the two monitors. Here is a brief description on how to get Clone mode on Windows and Linux for the Nvidia cards. Windows 2000/XP:
Choose the OpenGl settings and enable quad buffered stereo API as shown below in fig 3.3-a. Also choose additional properties and enable stereo in OpenGL and 'Use nView clone mode' as shown in fig 3.3-b .
3. Click OK. Linux: 1. The /etc/X11/XF86Config-4 file controls how the display should look. Please look at the README file that Nvidia provides. The following is a chunk out of this file relevant to setting up Twinview. Section "Screen" Subsection "Display" Option "TwinView" EndSection You can download an example XF86Config-4 file here. This file is configured to run in 'Clone mode' where both your monitors will show the same desktop instead of the desktop being stretched across. Change the 'TwinViewOrientation' to 'RightOf' (or 'LeftOf') ; restart the Xserver and you should see the desktop stretch across the two monitors. 3.2 Set up screen and projectors. This step involves the mounting of projectors and placing the screen. There are two projection techniques:
If immersion isn’t absolutely necessary, and stereoscopic 3D is the main goal, then front projection works effectively. Rear projection systems are a little more cumbersome to set up and more expensive, but the display is more compelling than front projection. Again, there are two ways you can mount the projectors: 1. Ceiling projection. 1. Ceiling Projection In this case the projectors are hung inverted from the ceiling and The projectors are usually hung from a slot in the ceiling to hold them, so that they face the screen.
Mount projectors on a metal (or fire treated wood) shelf 10" x 2 feet, side by side with the lenses as close together as possible, with their horizontal crosshairs aligned and their vertical crosshairs parallel. In this case since both the projectors are inverted as seen from the screen the options in the projectors must be changed to produce inverted images so that they beocme straight when projected on the screen. This can be done by using display controls in the projectors. TIP : When you order projectors from the vendor, remind him
to send you the data backs (look at fig. 3.2.2) for
the projectors. These modules allow for more connections like VGA,
DVI, 2. Table Mounted Projection
TIP : Set the brightness on your projectors to 50%. The bulbs and the polarizers will live longer. 3.3 Split signal from the Graphics card. The signal from the ports of the graphics card are give to two splitters one for each eye. The signal for the right and left image are split up and the two signals from each splitter are given to the monitor and projector respectively i.e the signal from the 2 splitters for the left and right images must be next given as input to the respective projectors. The converter from VGA to DVI if needed needs to be employed. The polarizers need to be setup next in front of the projectors so that the light from the projectors gets polarized. Stick the polarizer on the projector using velcro. In our early experiments we used duct tape or paper clips to fix the polarizers directly on the bulb; it's safer to stick them at least 5 inches out in front of the projector bulb. The pictures below illustrate the step-by-step technique to put polarizers together.
The alignment of the projectors is the most important and time-consuming
part of the assembling process. Download this image as a jpg
or as a ppm.
You can view it with Irfanview
or with Internet Explorer in fullscreen mode on Windows. On Linux
use Viewer
or just use xview (type xview
-fullscreen GeowallAlignnment.jpg)
The projectors are said to be aligned when most of the left and right images geometrically overlap on the screen. It's almost impossible to get every part of the images to overlap perfectly since the projectors do not have shift lenses in them; so concentrate on getting the central portion of the image to overlap. In particular, get the words 'Geowall Alignment', the color bands and at least one of the words 'Focus' to overlap. Vertical disparity between the left and right eye images will hurt the viewer more than horizontal disparity in the alignment;so try to avoid vertical disparity. TIP :You can use the knobs on the stand or the mount to make the projectors throw light on the screen.the projector has adjustments for adjusting the focus and the zoom on screen. Use them to help with the alignment. A list of commonly used Geowall applications is given below. We recommend you start using Immersaview and Viewer(or WallView or Irfanview) first. Later you can experiment with the other software. You can find more detail on each application's URL and on the Geowall home page.
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