The Enhanced Video Surveillance System: A Long-Awaited Tool
April 2004
Security Technology & Design Magazine
The capabilities of CCTV systems have increased dramatically in the last five years, as has the ability of the security practitioner to design effective, cost-efficient video systems. The transition from VCRs to DVRs and now to video servers was welcome and useful. However, an honest consultant will admit to continued frustration with video implementation. Even when CCTV systems incorporate the latest in technology, all the issues of human monitoring remain. How many monitors can a security officer watch? How many video images should you put on a single monitor? How reliably can a security officer recognize and act on presented video information? How often should an officer be rotated out of a monitoring post?
Some security departments overcome these issues by painstakingly developing alarm actuation schemes, whereby the monitoring officer is alerted both visually and audibly when an event of concern is detected. Unfortunately, we now must often secure sites that do not accommodate even the craftiest of traditional alarm schemes, thus relegating the video system to an after-the-event forensics tool.
At least two vendors have tackled these problems, developing solutions that take the use of video in a security setting to a higher level. At the core of these products is a software algorithm that mimics the observation, analysis and judgment of the security officer. One vendor describes the process an officer goes through in this way:
Detection: Is there anything there?
Classification: What is it? Car? Boat? Bird? Man?
Location: Where is it?
Identification: Is it an authorized person? Is that person in the correct part of the site? (This is where the officer applies the site-specific policies.)
Response: What action, if any, is warranted based on the presented information?
Video-based motion-detection systems have long held the advantage in detecting movement or changes in the video scene. That advantage has also been the bane of these systems, in that they have in many cases been too sensitive, sounding alarms on everything from a bird flying through the scene to a whitecap on a water surface.
Algorithms have since been developed and applied to decrease these systems' sensitivity through various averaging and filtering techniques to eliminate items that do not represent a threat to the site. Once the system detects an object, it applies various tests in an attempt to classify the object, taking into accounts such characteristics as size, shape, width-to-height ratio and location. If the object fits one of the defined targets, it is marked.
After it has detected and classified the object, the system will track that object as it moves within the site. The system's ability to track these targets varies depending on the design of the CCTV system. The designer has to provide cameras in areas where movement of significant items is likely to occur. Various vendors handle the tracking activity differently. One does it digitally through calibrating fixed CCTV camera fields to GPS coordinates; the other provides a similar function through software-controlled pan/tilt/zoom cameras.
I was recently able to see a presentation that included a live, remote demonstration of one of these products. It deftly highlighted the system's ability to detect, classify, locate and track objects of various sizes and shapes in environments that would have been difficult, if not impossible, to address with previous tools. The primary operator interface was a digitized aerial photo of the site on which the software displayed the information it had derived from an array of cameras. Instead of seeing a picture of a car moving down a section of a roadway, we saw an icon of a car moving on the digitized site map, the path of which was synthesized from the fields of view of several cameras past which the car had traversed. Actual video scenes were available by clicking on the icon.
Systems of this type are finding a ready market among airports and ports. There are particularly useful with large sites, sites with irregular perimeters and sites whose perimeters do not have physical boundaries. As the number of new installations increases, the industry will learn more about how to effectively apply these systems to address real problems. In the meantime, find an opportunity to learn more about this emerging technology. The field will continue to expand.
Randall R. Nason, PE is a corporate vice president and manager of the Security Consulting Group at C.H. Guernsey & Co. His experience spans a broad spectrum of the security profession including threat assessment, vulnerability analysis and master plan development through complete system design and construction management.
Randall Nason, PE
Vice President
Manager, Security
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