Conversely, if a single image is displayed over multiple displays, as in a true video wall application, the pixel capacity of each display is summed. As an example, four displays with individual resolution capacities of 1024 x 768 arranged in a two-by-two configuration would provide a resolution capacity of 2048 x 1536. Therefore, a UXGA (1600 x 1200 pixels) graphics-standard computer image could be reproduced as a single image with no degradation of the original signal. Viewing distances from the operator to the screens, along with angle of view on both the horizontal and vertical planes, are other considerations in the placement of screens, as are reflective or direct screen materials and optical characteristics. As with any display device, special attention must be given to location and proximity to extraneous light-producing devices, which can cause screen glare and in severe cases completely wash out a projected or displayed image.
As previously mentioned, the processing components that enable us to display multiple images on a single screen or in the context of a virtual video wall can take on various levels of sophistication and offer a wide range of flexibility. Simple CCTV signals to high-resolution, computer-generated graphic signals can be accommodated by the electronics available and can be mixed and matched on a single screen or multiple screens as the application or need requires.
Standard equipment interface control protocols for automation processing have also been introduced to allow computer-generated images, such as alarm and access control monitoring, fire monitoring and virtual floor plans, to be automatically selected and displayed upon an exclusive alarm event or condition. Displays and processing components featuring redundant lamps and power supplies, hot swapping components and extended life expectancies have already been developed for mission-critical 24/7 applications and proven in the market in numerous utility and network monitoring command-and-control centers. Software-switching programs have been developed to allow screen image relocation of critical displayed information at the touch of a button, touch screen or mouse click without any need for hardware reconfiguring.
As you can see, there are many questions you must answer in order to determine the best overall display concept for your monitoring needs. There are certainly inherent advantages and disadvantages to each of the display technologies mentioned here. No single technology or display technique is appropriate to support all monitoring applications or environments. The visual material content, signal types and properties of images, physical environment, viewing angles, component useful life span, screen image burn-in, refresh rates, pixel burn-in, electrical power requirements, heat generation and costs are only a sampling of the issues that must be analyzed and evaluated.
A carefully planned approach must be established, taking into account many of the above-mentioned factors and dynamics, before implementation. One must assess operational impact versus cost of implementing such surveillance system displays. The costs associated with implementing these high-tech display devices and processing electronics can be quite high. However, the costs associated with not implementing them may be even higher.
Mr. Phillip Schramm is a consultant with Sako & Associates Inc. Located in the Arlington Heights/Chicago office, Mr. Schramm has 30 years of project experience in the design of facilities for audio-visual and communication systems as well as systems designs themselves. To learn more about SAKO and their services, visit www.sakosecurity.com.