Technique used for creating large video displays, without a video projector

A video wall is a special multi-monitor setup that consists of multiple computer monitors, video projectors, or television sets tiled together contiguously or overlapped in order to form one large screen. Typical display technologies include LCD panels, Direct View LED arrays, blended projection screens, Laser Phosphor Displays, and rear projection cubes. Jumbotron technology was also previously used. Diamond Vision was historically similar to Jumbotron in that they both used cathode-ray tube (CRT) technology, but with slight differences between the two. Early Diamond vision displays used separate flood gun CRTs, one per subpixel. Later Diamond vision displays and all Jumbotrons used field-replaceable modules containing several flood gun CRTs each, one per subpixel, that had common connections shared across all CRTs in a module; the module was connected through a single weather-sealed connector.[1][2][3][4][5][6][7][8] Eventually these cathode-ray tube-based technologies were replaced by LED arrays.

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Screens specifically designed for use in video walls usually have narrow bezels in order to minimize the gap between active display areas, and are built with long-term serviceability in mind.[9] Such screens often contain the hardware necessary to stack similar screens together, along with connections to daisy chain power, video, and command signals between screens.[10] 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 (in Projection-based screens).

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

Video walls are sometimes found in control rooms, stadiums, and other large public venues. Examples include the video wall in Oakland International Airport's baggage claim,[11] where patrons are expected to observe the display at long distances, and the 100 screen video wall at McCarran International Airport, which serves as an advertising platform for the 40 million passengers passing through airport annually.[12] 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 has enough size for the distant passerby to view photos while also providing the nearby observer enough resolution to read about upcoming events.[13]

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.[9] Software-based video wall technology that uses ordinary PCs, displays and networking equipment can also be used for video wall deployments.[14][15]

The largest video wall as of was located at the backstretch of the Charlotte Motor Speedway motorsport track. Developed by Panasonic, it measures 200 by 80 feet (61 by 24 m) and uses LED technology. The Texas Motor Speedway installed an even larger screen in , measuring 218 by 125 feet (66 by 38 m).[16]

Video walls are not limited to a single purpose but are now being used in dozens of different applications.

Controllers

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A video wall controller (sometimes called “processor”) is a device that splits a single image into parts to be displayed on individual screens. Video wall controllers can be divided into groups:

1. Hardware-based controllers.
2. Software-based PC & video-card controllers.

Hardware-based controllers are electronic devices built for specific purpose. They usually are built on array of video processing chipsets and do not have an operating system. The advantage of using a hardware video wall controller is high performance and reliability. Disadvantages include high cost and the lack of flexibility.

The most simple example of video wall controller is single input multiple outputs scaler. It accepts one video input and splits the image into parts corresponding to displays in the video wall.[17]

Most of professional video wall displays also have built-in controller (sometimes called an integrated video matrix processor or splitter). This matrix splitter allows to “stretch” the image from a single video input across all the displays within the whole video wall (typically arranged in a linear matrix, e.g., 2x2, 4x4, etc.). These types of displays typically have loop-through output (usually DVI) that allows installers to daisy-chain all displays and feed them with the same input. Typically setup is done via the remote control and the on-screen display. It is a fairly simple method to build a video wall but it has some disadvantages. First of all, it is impossible to use full pixel resolution of the video wall because the resolution cannot be bigger than the resolution of the input signal. It is also not possible to display multiple inputs at the same time.[18]

Software-based PC & video-card controllers is a computer running an operating system (e.g., Windows, Linux, Mac) in a PC or server equipped with special multiple-output graphic cards and optionally with video capture input cards. These video wall controllers are often built on industrial-grade chassis due to the reliability requirements of control rooms and situational centers. Though this approach is typically more expensive, the advantage of a software-based video wall controller vs the hardware splitter is that it can launch applications like maps, VoIP client (to display IP cameras), SCADA clients, Digital Signage software that can directly utilize the full resolution of the video wall. That is why software-based controllers are widely used in control rooms and high-end Digital Signage.[19] The performance of the software controller depends on both the quality of graphic cards and management software. There are a number of multi-head (multiple output) graphic cards commercially available. Most of general purpose multi-output cards manufactured by AMD (Eyefinity technology), NVidia (Mosaic technology) support up to 6-12 genlocked outputs.[citation needed] General purpose cards also do not have optimizations for displaying multiple video streams from capture cards. To achieve larger number of displays or high video input performance one needs to use specialized graphic cards (e.g. Datapath Limited, Matrox Graphics, Jupiter Systems).[20][21][22][23] Video wall controllers typically support bezel correction (outside frame of monitor) to correct for any bezel with LED displays or overlap the images to blend edges with projectors.

Matrix, grid and artistic layouts

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The integrated video wall scalers are often limited to matrix grid layouts (e.g., 2x2, 3x3, 4x4, etc.) of identical displays. Here the aspect ratio remains the same but the source-image is scaled across the number of displays in the matrix. More advanced controllers enable grid layouts of any configuration (e.g., 1x5, 2x8, etc.) where the aspect ratio of the video wall can be very different from that of individual displays. Others enable displays to be placed anywhere within the canvas, but are limited to portrait or landscape orientation. The most advanced video wall controllers enable full artistic control of the displays, enabling a heterogeneous mix of different displays as well as 360deg multi-angle rotation of any individual display within the video wall canvas.

Multiple simultaneous sources

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Advanced video wall controllers will allow you to output multiple sources to groups of displays within the video wall and change these zones at will even during live playback. The more basic scalers only allow you to output a single source to the entire video wall.

Network video wall

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Some video wall controllers can reside in the server room and communicate with their "graphics cards" over the network. This configuration offers advantages in terms of flexibility. Often this is achieved via a traditional video wall controller (with multiple graphics cards) in the server room with a "sender" device attached to each graphics output and a "receiver" attached to each display. These sender/receiver devices are either via Cat5e/Cat6 cable extension or via a more flexible and powerful "video over IP" that can be routed through traditional network switches. Even more advanced is a pure network video wall where the server does not require any video cards and communicates directly over the network with the receiver devices.[24]

Windows-based Network video walls are the most common in the market and will allow a much better functionality.[25]

A network configuration allows video walls to be synchronized with individual digital signs. This means that video walls of different sizes and configurations, as well as individual digital displays can all show the same content at the same time, referred to as 'mirroring'.[citation needed]

Transparent video walls

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Transparent video walls combine transparent LCD screens with a video wall controller to display video and still images on a large transparent surface. Transparent displays are available from a variety of companies and are common in retail and other environments that want to add digital signage to their window displays or in store promotions. Bezel-less transparent displays can be combined using certain video wall controllers to turn the individual displays into a video wall to cover a significantly larger surface.[26]

Rendering clusters

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• 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 a large display wall (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.[27]
• 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.[28]
• 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.[29] The system displays high-resolution still images, 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.[14]

See also

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• Multi-image
• Multi-monitor
• Video sculpture
• VESA

Video wall vs. projector: Pros and cons, how to choose

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When you’re choosing between a video wall or a projector, it can be tough to decide which one is beneficial for your business, is the most cost-effective and is the most efficient for your uses. However, this doesn’t need to be a difficult choice and can instead be an opportunity to reflect on your business requirements and help you identify the best technology to meet your business goals. 

Both video walls and projectors come with significant presentation benefits and can help improve interactivity and engagement levels. But it's best to choose just one technology to ensure you don’t confuse operations, as this may impact presentation and conference quality.

To ensure you do this, we’ve created this comprehensive guide to video walls vs projectors, including the pros and cons, with a guide on how to choose the best solution for your company. 

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With this guide, you’ll be in a better place to make an informed decision about your presentation technology requirements.

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What types do video walls have? How does the technology work?

Before we get into the specifics of projects vs video walls it’s integral that we first define what a video wall is. 

A video wall is a collection of monitors that work together as a coherent screen, using video wall technology like processors, matrix switchers and controllers to coordinate imagery and ensure that pictures are displayed on the correct screen. 

These video walls are capable of displaying multiple snippets of information from a centralized platform, making them ideal for presentations and conferences where it’s necessary to distribute a high volume of information. 

The size of the video wall can vary depending on the user’s requirements. Some video walls are as small as 4x4, while others go all the way up to 144 x 72 in size. They’re very scalable and multi-functional, making them ideal for businesses with many presentation needs, as companies can use a video wall for conferencing, trade shows, presentations, office operations and much more!

AV enthusiasts and business professionals can use a few types of video walls. It’s important to remember, however, that different video walls may be more suited to specific uses, so consider your primary usage requirements when assessing the following three types. Here’s a guide to the three types of video walls: 

1. LED video walls

LED video walls are one of the most common types of video walls and are primarily used in advertising and display scenarios due to their bright and detailed displays. LED walls are capable of creating these bright and highly detailed displays by using many tiny LED lights. Many places worldwide make use of LED video walls, including Picadilly Circus in London and Times Square in Manhattan, New York. 

Their bright and eye-catching display makes them ideal for companies needing digital signage to advertise their business, as they ensure that customers won’t miss your advertisement.  

The reason why businesses tend to use these displays is, unlike other types of video walls, each pixel (or LED light) emits its own light, ensuring that all parts of the video wall are visible. We also tend to see LED video walls in places such as museums to depict images and video footage or in shop windows to attract customers.  

Like all things, there are some pros and cons to using LED video walls. Here are some examples: 

Pros

• Low energy use - One of the significant benefits of LED video walls is that they tend to use much less energy than standard video walls. This can lower your operational costs significantly. 
• Environmentally friendly - As LED lights use less energy, companies can decrease their reliance on fossil fuels and reduce their carbon footprint, which is better for the environment and also your company profile. 
• Long life-span - LED lights tend to last significantly longer than LCD or rear projected cube walls, meaning users spend less on costly repairs or replacements. 

Cons

• More expensive - Despite the positives, LED walls tend to have a much higher upfront cost than LCD walls. However, the operating costs are much lower, meaning users get better value for money.  
• Thinner - LED walls also tend to be much thinner, which can make them break easily due to fragility. This may make them less transportable than other video wall options.
• Age and temperature can impact light quality - As LEDs age, they can cause color shift, which may impact quality. Similarly, the temperature can have an impact on LEDs, so if you’re using your LED video wall in colder climates, this may impact performance.  

2. LCD video walls

LCD video walls are the most common type of video wall on the market due to their accessibility. These consist of multiple LCD panels put together to create the illusion of a single wall. It’s not uncommon for LCD walls to be used in offices, broadcasting environments, mission control centers and control rooms due to their versatility and easy accessibility. Depending on the type of LCD video wall you invest in, the quality can differ. 

Some LCD video walls that have a lower upfront cost may have wider bezels, whereas more expensive options tend to include thinner bezels to give a more seamless look to a video wall. Despite their versatility, there are some pros and cons you will need to consider before you decide to invest in an LCD video wall. Here's a brief guide to their pros and cons: 

Pros 

• Lower upfront cost - LCD video walls tend to be the least expensive option on the market for consumers. That means companies can save some money when investing in video wall technology, giving them more opportunities to invest in video wall technology. 
• Sturdier option -  LCD video walls can be much sturdier options than LED walls, making them ideal for transportation and longer usage. 
• Easy availability - LCD video walls may be much more available than other video wall types, as LCD panels are easy to come by for most major technology brands.  

Cons

• Inefficient energy consumption - One of the most significant downsides to using an LCD video wall is that they tend to use a lot of energy to operate. This increases a company’s reliance on fossil fuels and other polluting energy sources, which can contribute to environmental damage. 
• More expensive operational cost - Alongside environmental damage, high energy usage is also associated with increased energy bills. As the wholesale price of gas increases and the energy market remains unstable across Europe, using an LCD video wall can be an inefficient use of company funds. 
• Harsh bezels that impact quality - As LCD walls are much cheaper options, they tend to use less seamless monitors, resulting in harsh bezels (borders) interrupting video quality. This can impact engagement if you’re presenting to an audience and disrupt the flow of your video display.

3. Rear-projection video walls

Rear-projection video walls differ significantly from other video wall options. Rear projection walls, also known as rear projection cubes are used across industries and are known for their usage in control rooms. Extremely narrow bezels and high video quality make them a reliable option for companies.

This method differs from the other two options as they use projection behind the screen instead of in front. This significantly reduces the impacts of shadowing and improves image quality. We tend to see rear-projection video walls in large entertainment settings such as sporting venues or in music events due to their very large screen capacity. Here’s a guide to some of the pros and cons that users may experience with this video wall: 

Pros 

• Reduces shadowing - Due to the placement of the projector, rear projection video walls significantly reduce the impact of shadowing and fading, making the screen’s visuals look more sinuous and high-quality. 
• Thin bezels - Unlike LCD walls, rear-projected cube walls tend to have thinner bezels, increasing production quality. 
• Provides a more professional look - If you’re a company that is very conscious of image, then a rear projection cube wall is beneficial. This is because they look very professional, making you seem knowledgeable and invested in AV technology and production value.

Cons 

• Technology can be harder to access due to the placement - As projectors are situated behind the screen, it can be difficult to conduct any repairs or maintenance once it’s in place, especially if you’re presenting in an inaccessible environment once the screen is up. 
• Requires a very powerful projector - To ensure that your audience members can see what’s happening on the screen, a rear-projected cube wall requires a very powerful projector which may be more costly. 
• Needs larger projection space -  Unlike front projection, rear projection requires a much larger surface area to display a full image, making it more difficult to create a rear-projection video wall that’s suitable for smaller spaces. 

What is a projector? How does it work? 

A projector is a device that uses beams of light and lenses to display images on a video wall or blank screen. This technology works by shining a powerful light through a lens. Standard lamp based projectors operate by using colored lenses, filters and a color-wheel to display images. However, there are a few types of projectors. 

One of the most common ones that we see in cinemas, education settings and conferences is an LED projector. This projector uses green, red and blue LED bulbs to create something known as ‘white light’. This is then filtered through a lens and is displayed across a screen through beams of light. Projectors are some of the most versatile display technologies out there and are easily accessible. Despite this, there are some pros and cons. Here’s a guide to the perks and disadvantages of projectors: 

Pros

• Space saving - Unlike large video walls, projectors are primarily a single box, meaning they save more space which may be beneficial for smaller offices. 
• Inexpensive - It’s very easy to find cheap yet high-quality projectors for your business, making it good for companies wanting to cut down costs. 
• Highly adaptable -  As projectors are transportable, they’re highly adaptable to changing presentation requirements. 

Cons 

• Requires a dark room - One of the biggest drawbacks to using a projector is that they require a dark room to operate, which can make it harder for people to conduct other tasks while watching presentations, such as taking notes. 
• Creates shadowing easily - The most obvious downside is that upfront projection is easily interrupted by people walking in front of the beams of light, resulting in shadowing.
• Integrated projectors can require lengthy installation - If you’re using a projector as part of an interactive whiteboard, this can require a lengthy installation process with costly maintenance demands.

Video wall vs. projector: How to choose? Which is the better solution for your company?

The solution you choose for your company will typically depend on your individual usage requirements. You should consider your business needs before you decide to invest in either option. Ask yourself questions about your audience requirements, goals for engagement and budget, as this will help to guide your decision. 

The best solution for your company will depend on your needs. For example, if you’re looking to produce engaging displays with high levels of interactivity and high information volume distribution, then a video wall may be better for your company. However, for companies looking to improve operations on a budget and require a transportable solution, then a projector may be better for you. 

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