A Guide to the Key Components
All video walls comprise of three basic components:
- Modular Displays
- Controller Hardware
- Control Software
Modular Display Technologies:
For the past 20+ years DLP®-based rear projection cubes, in 50” to 80” diagonal individual component screen size, were the dominant display technology used to create video walls in control rooms and command centers. Lamp/illumination technology advanced, resolution increased, mullions got thinner, and prices fell over time. However, their physical depth and rear access for maintenance resulted in a minimum practical six feet overall space requirement behind the screen, typically much more for very large video walls that would require a motorized scissor lift for maintenance access to upper rows. They also typically had a somewhat constrained viewing angle, especially vertically, and the thin mullions between screens were a visual distraction.
Current projection cubes are marketed as ‘laser’. This is simply the illumination technology used. They use the same Texas Instruments DLP® micro-mirror imaging chips as all projection cubes sold since the 1990s.
Today, only one company still sells projection cubes, and the technology is fast disappearing from the market, displaced by two newer technologies that have one overwhelming advantage: a total installed depth typically measured in inches, increasingly with wall-mounted front serviceability.
For the past 10 years, 55” diagonal LCD panels have been used in smaller control rooms. Over time their suitability for display of static graphics and lifespan for 24/7 applications have significantly improved, as has the ‘mullion’ (live pixel-to-live pixel distance from screen to screen) to as little as 0.88mm today: almost seamless. They are also attractively priced for a given overall display area. However, they have two disadvantages: their overall lifespan is relatively short compared with the other display technologies and frequent model changes makes large LCD walls impractical since, in the case of panel failure (typically the screen itself), old and new model panels won’t match or typically even fit.
LED display is the future of control room display. It is bright, very high contrast, and completely seamless, with near perfect uniformity of brightness and a very wide horizontal and vertical viewing angle. It also has an effective lifespan that is more than double that of LCD and the small individual tiles can be easily replaced and repaired over its extended life. The only constraint on its universal adoption is its cost, which unlike other technologies is directly related to its pixel pitch (i.e., its pixel density).
Compared with matrixed LCD panels where the pixel pitch is standard and exceeds the visual acuity of viewers in a typical control room, LED cost is a function of pixel pitch, and pixel pitch requirements are a function of minimum viewing distance requirements. If the pixel pitch is too large for the viewing distance, the video wall will look pixelated and the content indistinct.
LED is already price-compatible with the prior projection cube display technology at all but the narrowest pixel pitches, and pricing has been decreasing steadily, though it slowed somewhat with the supply chain constraints relating to the pandemic.
Since LED is the recommended large-scale display medium for control rooms, and the only realistic option for large video walls, a deeper dive into pixel pitch and its related visual acuity and cost is important.
We primarily purchase our LED technology from the world’s largest supplier, due to its quality, price points and product range. It is also available, TAA compliant, with EU manufacture.
Standard (55” HD) LCD matrix panel pixel pitch is: 0.63mm, fine enough for any control room application, with a minimum recommended viewing distance of 7ft.
Indoor LED, known as ‘narrow pixel pitch’ or NPP, suitable for control room applications, typically ranges from 0.6mm to 1.8mm pixel pitch and since cost is a function of pixel pitch – the narrower the pitch, and the greater the pixel density, the higher the cost, it is prudent to select the widest pixel pitch acceptable for the viewing environment, such that even to the closest viewers (typically those sitting in the front row of consoles), all content including detailed graphics and text will look crisp, easily readable and not pixelated.
There is a simple formula, based on a trigonometric function that relates pixel pitch and minimum recommended viewing distance1. This is the same calculation made by Apple when they designate a display Retina, based on the anticipated device screen viewing distance.
- Pixel pitch (mm) multiplied by 11.3 = Minimum Viewing Distance (in feet)2
- Minimum Viewing Distance (in feet)2 divided by 11.3 = Maximum Pixel Pitch (mm)
These are minimum recommended viewing distances for standard NPP LEDs3.
|Pixel Pitch||Minimum Viewing Distance|
For many years video wall controllers have mostly been computer based: typically, vendor branded, white-label servers or rackmount workstations running Windows©, with graphics and peripheral cards supplied by one of two specialty video wall controller card manufacturers. This approach allows controller vendors to sell their products at high mark-ups through resellers.
Activu instead offers major brand servers/workstations and graphics cards, typically Dell and AMD, which we buy (and sell) directly and mark up modestly. The quality is higher, prices much lower and the level of direct service provided by the major brands is so much higher than we or our competitors could ever offer directly (as little as four hours, on-site). We encourage our channel partners to do the same!
With LED there is a separate control unit typically provided by the LED manufacturer that is an interface between the controller’s graphics cards and the LED modules and individual LEDs.
Most controller software is limited to the orchestration of content on video walls. The software runs on the controller and the user interface might run on a separate computer or in a web browser.
Activu’s Vis/ability® platform does a great deal more. Video wall functionality is fully featured, but video walls are just one type of end point and vis/ability can also run on desktops and mobile devices, allowing the sharing of information between people, devices and displays across the organization and beyond with collaborative tools. Vis/ability can also integrate with a client’s information ecosystem to automatically distribute incident-related information to stake-holders and displays across the organization and even between organizations, among other broad functionality.
Paul Noble founded Activu Corporation (formerly Imtech) in New York in 1983, making it the first company to develop and sell video wall technology in the United States. Born in London, Paul attended the London Film School and had an early career in film and television before moving to the United States. He later went on to receive an MBA from Columbia Business School. He can be reached through Activu’s contact form here.
- The methodology behind this is explored in depth in the addendum ‘Visual Acuity Explained’ of my white paper: ‘Control Room Visualization’.
- The factor for meters is 3.7
- This is for the typical control room applications where detailed, static graphics will be displayed. Where only high-definition video will be displayed, a significantly closer viewing distance for any given pixel pitch is very acceptable. Some LED manufacturers use this more permissive use case, to calculate minimum acceptable viewing distance.