A video wall consists of multiple computer monitors, video projector

Video projector

A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other...

s, or television set

Television set

A television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...

s tiled together contiguously or overlapped in order to form one large screen. Typical display technologies include LCD panels

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

, LED arrays

LED display

An LED display is a flat panel display, which uses light-emitting diodes as a video display. An LED panel is a small display, or a component of a larger display. They are typically used outdoors in store signs and billboards, and in recent years have also become commonly used in destination signs...

, DLP tiles, and rear projection screens

Rear-projection television

Rear-projection television or RPTV is a type of large-screen television display technology. Up until the mid-2000s, most of the relatively affordable consumer large screen TVs up to used rear-projection technology...

.

Screens specifically designed for use in video walls usually have narrow bezel

Bezel

Bezel may refer to:* Bezel setting, or bezel, the rim which encompasses and fastens a jewel, watch crystal, lens or other object* The sloping facets of the crown of a cut gem such as in diamond cutting...

s in order to minimize mullion

Mullion

A mullion is a vertical structural element which divides adjacent window units. The primary purpose of the mullion is as a structural support to an arch or lintel above the window opening. Its secondary purpose may be as a rigid support to the glazing of the window...

 - the gap between active display areas - and are built with long-term serviceability in mind. Such screens often contain the hardware necessary to stack similar screens together, along with connections to daisy chain

Daisy chain (electrical engineering)

In electrical and electronic engineering a daisy chain is a wiring scheme in which multiple devices are wired together in sequence or in a ring...

 power, video, and command signals between screens. A command signal may, for example, power all screens in the video wall on or off, or calibrate the brightness of a single screen after bulb replacement.

Reasons for using a video wall instead of a single large screen can include the ability to customize tile layouts, greater screen area per unit cost, and greater pixel density per unit cost, due to the economics

Economics

Economics is the social science that analyzes the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek from + , hence "rules of the house"...

 of manufacturing single screens which are unusual in shape, size, or resolution

Display resolution

The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...

.

Video walls are sometimes found in control room

Control room

A control room is a room serving as an operations centre where a facility or service can be monitored and controlled. Examples include:*in television production, the master control is the technical hub of a broadcast operation common among most over-the-air television stations, television networks...

s, stadium

Stadium

A modern stadium is a place or venue for outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a structure designed to allow spectators to stand or sit and view the event.)Pausanias noted that for about half a century the only event...

s, and other large public venues, such as Oakland International Airport's

Oakland International Airport

Oakland International Airport , also known as Metropolitan Oakland International Airport, is a public airport located south of the central business district of Oakland, a city in Alameda County, California, United States...

 baggage claim

Baggage claim

In airport terminals, a baggage claim area is an area where arriving passengers claim checked-in baggage after disembarking from an airline flight. The alternative term baggage reclaim is used to mean the same thing at many airports outside the USA In airport terminals, a baggage claim area is an...

, where patrons are expected to observe the display at long distances. Video walls can also benefit smaller venues when patrons may view the screens both up close and at a distance, respectively necessitating both high pixel density and large size. For example, the 100-inch video wall located in the main lobby of the Lafayette Library and Learning Center

Lafayette Library and Learning Center

The Lafayette Library and Learning Center is a library and learning center in Lafayette, California that opened in 2009. The Lafayette Library and Learning Center is also home to the Glenn Seaborg Learning Consortium, a partnership with the region’s leading arts, culture, and educational...

 has enough size for the distant passerby to view photos while also providing the nearby observer enough resolution to read about upcoming events.

Simple video walls can be driven from multi-monitor video cards, however more complex arrangements may require specialized video processors, specifically designed to manage and drive large video walls. There is also new software-centric video wall technology that uses ordinary PCs, displays and networking equipment.

Latest Advancements

Researchers around the U.S. have been advancing video wall technology in recent years.

Jason Leigh and others at the Electronic Visualization Laboratory, University of Illinois, Chicago, developed SAGE, the Scalable Adaptive Graphics Environment, allowing the seamless display of various networked applications over an LDW system. Different visualization applications such as 3D rendering, remote desktop, video streams, and 2D maps, stream their rendered pixels to a virtual high-resolution frame buffer on the LDW. Using a high-bandwidth network, remote visualization applications can feed the streams of the data into SAGE. The user interface of SAGE, which works as a separate display node, allows users to relocate and resize the visualization stream in a form of window, which can be found in a conventional graphical user interface. Depending on the location and size of the visualization stream window on the LDW, SAGE reroutes the stream to respective display nodes.

Chromium is an OpenGL system for interactive rendering on graphics clusters. By providing a modified OpenGL library, Chromium can run OpenGL-based applications on a LDW with minimal or no changes. One clear advantage of Chromium is utilizing each rendering cluster and achieving high resolution visualization over a LDW. Chromium streams OpenGL commands from the `app' node to other display nodes of a LDW. The modified OpenGL library in system handles transferring OpenGL commands to necessary nodes based on their viewport and tile coordinates.

David Hughes and others from SGI developed Media Fusion, an architecture designed to exploit the potential of a scalable shared memory and manage multiple visual streams of pixel data into 3D environments. It provides data management solution and interaction in immersive visualization environments. Its focus is streaming pixels across heterogeneous network over the Visual Area Network(VAN) similar to SAGE. However, it is designed for a small number of large displays. Since it relies on a relatively small resolution for the display, pixel data can be streamed under the fundamental limit of the network bandwidth.

Based on video wall display technology developed at University of California, Irvine’s California Institute for Telecommunications and Information Technology (Calit2), Hiperwall, Inc. was formed to commercialize a video wall system that offers advanced software functionality and interface with standard PCs, monitors and Ethernet network.

The system displays still images up to 1GB resolution or larger, HD videos, live HD video streams and PC applications. Multiple feeds can be displayed on the wall simultaneously and users can reposition and resize each feed in much the same way they move and resize windows on a PC desktop. Each feed can be scaled up for viewing on several monitors or the entire wall instantly depending upon the user’s discretion.

External links

• Penn State's High Resolution Display Wall
• Setting up a Video Wall with NMM - Using Open Source software for setting up a software-based video wall