in January 2004
Demand for Display
Wall Controllers Increases
By John Stark
Presentation and display technologies today are
more closely interwoven with the IT environment than ever
Editor’s Note: This is the
second of two parts. Part 1 appeared
in November 2003.
Presentation and display technologies
today are more closely interwoven with the Information Technology
(IT) environment than ever before. It has never been more
important for AV and IT professionals to work together,
or for AV systems integrators to appreciate the overall
IT context in which their systems will function.
For many organizations, this
close relationship is most visibly on display in a control
room. These facilities come in all sizes and are dedicated
to a wide range of functions, but they all have one thing
in common: a large display, often an entire wall of video
and data displays.
client may decide early in the design and construction project
that he wants a control room with a display wall. All too
often, however, the particulars are left until later, and
the client, architect and contractor all discover they cannot
just buy a display wall off the shelf. Indeed, the process
of choosing equipment and infrastructure for control-room
displays often turns into a fundamental review of the room’s
mission. This review should address a number of basic questions,
whose answers will shape decisions about how the room will
be designed, equipped and used.
Every display wall really
is a multi-part system. The most visible, of course, is
the screen or screens. The real heart of the system, though—and
the key to its success—is the control system that
drives those screens. The choice of a display wall controller
is critically important, and this choice is influenced by
a variety of factors.
In our examination of the
demand for display-all controllers here, I will discuss
some of these factors, and highlight a few of the elements
that must be weighed in answering them.
What Will be Displayed?
This is the most fundamental
question, and the answer will drive the selection of the
appropriate display wall controller and other equipment.
• Video sources: Video sources include television
signals, usually in color and typically available as analog
signals, either composite or S-video (Y/C). The video may
be coming from a TV tuner, a VCR or DVD player, a video
teleconferencing system, or closed-circuit video cameras.
Sometimes only one video signal is needed, such as for a
weather channel. Other applications, notably traffic-management
centers, may have hundreds of video signals.
Several issues arise regarding
the way video is to be displayed: How many video signals
must be displayed at one time? How many on a single projector?
Will the images be upscaled or downscaled and by how much?
What update rate is required? (Video usually refreshes in
• RGB sources: RGB sources are signals that don’t
follow television standards. They usually are scanned progressively.
That is, the entire image is refreshed in a single pass,
rather than the “interlaced” or alternate-line
method used in television. RGB color components are also
different from composite or S-video. Typical RGB sources
are computer outputs, and the resolution can range from
VGA (640x480) to UXGA (1600x1200).
RGB sources can be “captured”
and displayed in a window on the display wall. RGB capture
is a good way to pre- sent the display of a single computer
on the wall for everyone in the room to see. The signal
can be upscaled to make it easier to see (e.g., a 1280x
1024 signal can be zoomed to display over several projectors
on the wall covering, maybe, 2560x2048 pixels).
RGB is kind of a “universal interface” because
virtually any progressive-scan RGB signal can be captured
and displayed. Even an application running on a legacy system
with no interface to modern computers can still display
on the wall. RGB is also useful if the application, for
security reasons, has to be run on a private network and
can’t communicate with the wall controller.
Many of the issues that apply to video also apply to RGB,
along with questions unique to RGB. Does the RGB processor
capture all the VESA standard display formats? Are other
display formats also required? Can custom formats be handled?
How long does it take to lock onto a new signal that is
presented? Can signal acquisition be coordinated with an
• Local applications: Many of the display wall controllers
available today actually are computers in their own right,
with fast Intel processors, lots of main memory, disk-drive
storage, networking capability and general-purpose operating
systems such as Microsoft Windows or Linux. This not only
provides a powerful, intelligent platform for implementing
a highly flexible, feature-rich wall controller but also
means that many applications can be run locally, on the
wall controller itself.
Key questions here are, of course, compatibility with the
operating system and whether there is enough CPU power and
memory/disk storage for the application. Another question
that may not be so obvious is whether the application is
well-behaved when given a large window. If your application
runs fine on a desktop with a window of 800x600 pixels,
what happens when you open a big window on the display wall
with 2000x1500 pixels?
• Network applications: Network applications should
run fine on the display wall controller because most controllers
come with network interfaces. The latest ones have Gigabit
Ethernet NICs for high-speed communications. Once again,
operating system compatibility is a key issue.
Many control rooms operate in a heterogeneous environment
where both Windows and Unix/Linux machines may be present.
A good way to provide interoperability here is with the
X Window System. If the wall controller uses the Linux operating
system, then an X Window user interface will be present
and X applications from other computer servers will easily
display on the wall. However, this provides limited interoperability
with Microsoft Windows applications.
On the other hand, if the display wall controller is based
on the Windows operating system, there will be good interoperability
with other Windows computers on the network. Furthermore,
if the wall controller includes an X Window user interface,
you will also have compatibility with all the Linux, Unix,
Solaris, VMS and other applications implemented to the X
• Network (streaming) video: Streaming video, ubiquitous
these days, is used frequently on desktop PCs and is beginning
to play a major role in control rooms. This is a good example
of an application that has problems scaling to display wall
size. Streaming video typically is low resolution, 320x240
pixels or smaller. Although this can be acceptable on a
desktop monitor when you are viewing it from 18 inches away,
it will not be large enough on a display wall when viewed
from 10 or 20 feet. That means the streaming video must
be upscaled to a larger window size.
Decoding compressed video
is a computer-intensive task that today’s powerful
processors handle with ease. But if you further burden the
processor with the task of
upscaling the decoded video to a large window size, you
won’t achieve real-time operation.
Such upscaling is beyond the
reach of most general-purpose processors and is best handled
by an external device that decodes streaming video to a
standard analog video signal.
• Network RGB capture: Proprietary programs that allow
you to operate one Windows PC from a remote Windows PC via
the network have been around for many years. These programs
work well on a one-to-one basis with small displays, although
they are slow and burden both the network and the processors
of both PCs. They have been used in display wall environments
with limited success.
In a display wall environment,
one big problem involves the burden on the CPU if the display
is upscaled to a large window size. Viable solutions based
on a tool called Virtual Network Computing use open software
to allow cross-platform operation between Windows, Linux
and other operating systems. For the control-room environment,
this not only provides convenient display of network-connected
computers, but also a network-based method of interacting
with the computers themselves. Unfortunately, this position
does not provide ubiquitous access to all systems, because
the technology cannot display in real time or support the
3D and video standards available.
All of these critical questions
about data types and sources are addressed generally by
modern display wall controllers, although their individual
Many control rooms must draw
data from older legacy systems as well as from more recently
implemented networks and applications. The most common pairing
is Windows and UNIX, particularly in organizations that
have moved from a UNIX-based workstation environment to
a more economical Windows PC strategy.
If the installation is predominantly
UNIX based, it’s best to craft a solution that provides
native UNIX tools and interfaces. Windows applications can
be integrated into the X Window environment using a simple
and free tool called a Visual Network Computer (VNC). VNC,
a client/server application that sends graphical screen
content over a network connection, has some drawbacks in
performance and scalability, but may be appropriate for
In a Windows setting, it’s important to choose a Windows-centric
solution and augment it with UNIX tools. X Window content
can be displayed in a Windows environment by using a Windows-based
Blending these distinct environments
is a crucial job, and one that an experienced systems integrator
is ideally qualified to execute.
From Desktop to the Big Wall
Few Windows-based PCs support
screen resolutions of more than 1600x1200 pixels, with most
operat ing at a level below that, typically 1280x1024. In
contrast, a 4x2 array of 1600x1200 pixel screens in a display
wall offers usable “pixel real estate” of 6400x2400.
Many display walls go even larger, sometimes up to 10,000
pixels of horizontal resolution.
Any solution that simply enlarges the desktop display will
actually lose clarity and readability as it gets larger
rather than benefiting from the additional resolution. Moreover,
when a display designed for the desktop is transported to
such a large canvas, it may exhibit artifacts, become unstable
or even crash the computer system—hardly acceptable
in an environment requiring 24/7 availability.
The real benefit of increasing
screen size and resolution is that it becomes possible to
put more detail on the screen. Rather than the same display
eight times larger, the user can see eight different displays
simultaneously, or some other combination of windows and
It is also important to understand the tradeoffs in moving
to a very large display. While a single monitor at 1280x1024
requires about 2.6 megabytes of data for its display, an
eight- or 10-screen wall requires eight or 10 times that
much. Handling all of this data affects drawing speeds,
the ease with which windows can be moved or resized and
One of the ancillary but important
missions for many control-room installations today is marketing.
Telecoms and other companies often use their Network Operations
Center (NOC) to demonstrate the scope of their resources
and the sophistication of their command and control operations.
An impressive appearance is a prime consideration in these
At the opposite extreme are facilities such as those operated
by electric-power companies, where displays provide real-time
data to support critical decisions.
In these settings, the display
wall must be a completely interactive tool, pulling data
quickly from dozens or hundreds of sources, displaying it
in meaningful ways and enabling managers to make fast, sound
decisions—whose results are also displayed quickly
and usefully on the wall.
Control rooms present obvious
security concerns because they so often display critical
information that an organization wants to keep to itself.
A large display wall magnifies these concerns through its
simple visibility. Thus, the first line of defense for the
client is to control access to the room itself. Who is allowed
to be there?
A second, related issue, is
that of identifying and tracing changes. A display wall
is a powerful “anonymizer,” i.e., when a change
appears on the screen, it can be difficult to tell immediately
who made the change, and at which workstation. Part of the
solution, clearly, lies with the organ- ization’s
system of access and editing permissions.
Another option is to make
the display wall itself read-only. Thus, all changes to
data must be done on the appropriate workstations by the
authorized individuals, and receive the correct management
review and approval before being displayed. It is also possible
to allocate certain portions of the wall to specific operators.
Although display technology provides some flexible options,
these critical decisions must be driven by organizational
The critical questions in
planning a control room do not all focus on technology.
The people who will use the room are not mere generators
and consumers of data: They are people.
Will they be able to read a certain size type from their
desk 20 feet away? If you make the type larger, will people
up close be able to read it? Will someone in a corner of
the room, viewing the display wall at an angle of 50 or
60 degrees, be able to see everything clearly? Does your
choice of color enhance readability or detract from it?
Will users interface with
the displays using such familiar tools such as a keyboard
and mouse? Will they see their inputs displayed immediately?
Some of the factors that help
determine the success of a control room, such as color schemes
for the furniture, carpets and walls, are esthetic, and
it may be tempting to call them matters of individual taste.
Yet it is possible to quantify the impact of room esthetics
on functionality and productivity, and an experienced systems
integrator can provide valuable advice in this area.
A Sound Approach
Much of the success or failure
of a project takes shape during the development of the Request
for Proposals. All too often, the first indication that
an RFP is flawed comes at a bidders’ information meeting,
when questions outnumber answers and the project appears
beset by ambiguities and knowledge gaps. Contractors may
decline to bid on poorly defined projects, and clients often
realize how much additional fundamental analysis they need
This disaster can be largely
avoided if the RFP writing process includes someone who
thoroughly understands the entire control-room environment,
and can give adequate attention to all the types of concerns
we’ve outlined here. As a result, when you do issue
your RFP, it will be comprehensive, detailed and realistic.
Clients often visit operational
control rooms suggested by integrators. On such a visit,
the issues we’ve outlined should be a checklist. Find
out what kinds of data and data sources the room accommodates,
and try to see a variety of displays: surveillance video,
broadcast and cable TV, graphics, spreadsheets, videoconferences
and so on.
Try to sit at workstations
at varying angles and distances from the screen and judge
text readability for yourself. Spend enough time to get
a feel for what it is really like to work in this room.
Then apply your evaluation to your own project.
The Correct Controller
Four basic types of display controllers are available today:
• Multiple-screen PC
• Multiple-screen PC with specialized control room
• Multiple-screen, RGB-input-only processor
• Built-to-purpose display wall controller with RGB
and/or video inputs and control-room software.
The simplest of these options
is an off-the-shelf PC with a multiple-screen graphics controller
or multiple graphics cards. Often these systems are adequate
for small installations, but quickly lose relevance when
needs become more complex. Overlooked requirements in the
control room include longevity and vendor support. Systems
installed in control rooms must remain operational, often
for some seven to 10 years. However, this is well beyond
the lifespan of most PC technologies and the interest or
capability of most vendors catering to the off-the-shelf
market. As a result, customers are left with systems that
are not supported, who have nowhere to turn except to discard
the old system for a new one.
By adding a layer of control-room
software, users can enable their PCs to bring in applications
and displays over a network. This approach can also meet
many needs, but lacks the speed and performance necessary
for really critical tasks. Imagine a combat commander waiting
for his screen to refresh before finding out whether an
incoming aircraft is friend or foe! Ad- ditionally, this
solution still suffers from a lack of long-term vendor support,
a risk many users are unwilling to take.
The RGB-input-only processor
typically is a standalone device that displays inputs from
video, TV and computers. It doesn’t provide the ability
to process local applications requiring input from such
devices as workstations and PCs and, depending on the number
of RGB sources that must be displayed, plus the up or down
scaling required, it may be unable to respond in real-time.
Apart from being costly for large complex installations,
these systems do not provide the real-time input and manageability
that a PC infrastructure allows. Instead, users must interact
with custom software that often is designed for the entertainment
industry, rather than a control room.
The fourth option—the “augmented PC” controller—provides
the greatest range of capabilities. Essentially, these are
purpose-built to meet the client’s specific needs,
and they offer the greatest performance, reliability, ease-of-use
and maintenance over the broadest range of requirements.
They can pull data from the greatest number of sources and
display them in movable, scalable windows in near real-time.
The best of these processors
offer 24/7 operation with redundant components and hot-swappable
parts. They are self-monitoring, and alert users to conditions
that may require intervention. Indeed, these display wall
controllers integrate the capabilities of the other categories
while carefully addressing the specific requirements of
the control room. These high performance controllers provide
flexibility, ease-of-use, high-quality display, and long-term
maintenance and support. Moreover, these controllers are
available from a number of reputable manufacturers, giving
integrators and clients a great deal of choice.
Selecting the Best Controller
Today’s AV and presentation technologies, coupled
with increasingly powerful and flexible IT tools, offer
an unprecedented array of options in designing a control
room. The facility truly can be and do whatever the client
wants. Today’s display wall controllers are the key
to these capabilities, and selection of the best one is
critical to the most effective implementation.
An astute integrator will be attuned to the client’s
operational needs, budget or physical space constraints.
Often these decisions will differentiate the exceptional
systems integrator and his or her value added.