Setting Up The X Window System - HP xw3400 User Manual

Setting Up the X Window System

To setup the X11 manually, first you need to setup your /etc/X11/xorg.conf file (or XF86Config) by
starting with the sample config file, xorg.conf.vizcenter1 (click here), that is included with this white
paper. If using Xfree86, make sure you change keyboard driver to kbd driver and /dev/input/mice
to /dev/mouse.
Next, you need to select your resolution. The config file is setup to run the projectors at 1280x1024
at 96 Hz. If this is not the desired resolution and frequency, you need to change this. You'll need to
add a Modeline (unless you can use a standard mode such as 1280x1024). If you want to be
explicit about the resolution and the refresh frequency, just add the modeline generated by the gtf
command.
gtf 1280 1024 96
The output of gtf can be inserted directly into the xorg.conf file in the appropriate "Monitor" section
as below. (See Modelines in the sample file and add your new modeline there)
# Modeline for 1280x1024 projector or monitor with Stereo
# 1280x1024 @ 96.00 Hz (GTF) hsync: 103.87 kHz; pclk: 182.81 MHz
Modeline "1280x1024_96"
1028 1082 -HSync +Vsync
NOTE: Often the output of the gtf command is not optimal for the projectors or monitors that you are
using. You may need to find better timings from the display provider. For our Christie projectors, we
actually needed to use the modeline below to get full coverage of our screens:
# Modeline for 1280x1024 projector or monitor with Stereo
# 1280x1024 @ 96.00 Hz (GTF) hsync: 103.87 kHz; pclk: 182.81 MHz
Modeline "1280x1024_96"
1028 1082 -HSync +Vsync
Now you need to reference this modeline in the appropriate places of your config file. The easy way
to find this is just search on 1280x1024_96 and replace with the name you gave to your modeline.
Make sure that you do not replace the actual Modeline definition of the existing 1280x1024_96, just
references.
You need to be careful to also set the horizontal sync and vertical refresh based on the specs of the
projector. Search on HorizSync, SecondMonitorHorizSync, VertRefresh and
SecondMonitorVertRefresh and change accordingly as indicated below. The projector should provide
these through a mechanism called EDID, so you might try not having any explicit settings for
horizontal sync and vertical refresh as your first step and only add these if needed.
# In Monitor Section
HorizSync 30-120
VertRefresh 56-96
# In Twinview Section
Option "SecondMonitorHorizSync"
Option "SecondMonitorVertRefresh" "56-96"
Now we setup the overlap regions. This assumes that you have projectors that can blend in an
overlap region to provide a smooth transition from one projector image to the next. The way this is
done is that the NVIDIA cards will actually generate the same image on edges of both projectors in
the overlap region that you specify in the xorg.conf file. The projectors will then blend the overlap
region by having each projector intensity decrease linearly from full image intensity to 0 in the
overlap region (edge). In the sample config file, we used 15% of the image for overlap (15% of
1280 = 192 pixels). In order to specify a 192 pixel overlap region in between the left and center
projector, the Twinview option "MetaModes" takes an offset for each left edge. We are using
Twinview to drive the first two projectors. The first offset is +0+0 for the first projector since there is
no blending on the left edge of the left projector. The next offset in the "MetaModes" option is
+1088+0. This may not be intuitive ... but it is NOT an offset from one projector to the other, but
# or whatever your desired settings are
182.81
182.81
1280 1376 1520 1760
1280 1376 1520 1760
"30-120"
1024 1025
1024 1025
8