Wednesday, December 24, 2008
Using Video for Detecting Perimeter Violations
I have mentioned John Honovich’s web site about video surveillance on a couple of occasions. One of the interesting things about John’s site is that he has a wide variety of industry experts contributing to the site. Yesterday, after receiving my weekly update email from John I went to a recommended discussion by Nick Grange of C3 Shared Services about setting up video analytics for perimeter intrusion detection. False Positives One of the problems with and intrusion detection system is the issue of false positive alerts. You certainly want a system sensitive enough to detect anyone crossing the detection perimeter. Setting the system to be too sensitive, however, results in alarms when there is no penetration, a false positive. Every time there is an alarm there has to be some sort of response. Depending on the distance between the perimeter and the actual security zone this could be a full tactical security team response, sending a roving patrol/guard to check out the situation, or reviewing the video record of the area. Nick noted that his firm tested a variety of video analytic systems at a site and found a wide range of false positives, from a low of 175 to as many 16,000 in the week long tests. Depending on what your alarm response is, 175, or about one per hour, may seem like a lot, but 16,000 is way to many for any security program. I would suspect that the equipment supplier never warned their customers about the potential for high false-positive rates on the 16,000 false-positive system. System Optimization The other good thing about Nick’s short article is the discussion about system optimization. I particularly like his explanation of how his firm selects the distance between cameras in a perimeter surveillance system. The one point that he does not emphasize is that those distances are for optimum situations, flat and clear terrain. If there are ditches or other obstacles those distances may be greatly reduced. Even so the 60m per camera and 3 to 4 hours per camera fine tuning and system adjustments gives you an idea of how long it should take a contractor to set up a system for your facility. Too much longer or shorter in the contract bid ought to be questioned. Nick’s comment about monthly maintenance of the system should also be considered when bidding out such a system. Intrusion Detection Systems There are a wide number of different types of systems that can be used for perimeter intrusion detection. Each of these systems has its strong points and weak points. John’s site concentrates on video systems, so it should not be used as the only source of information about choosing such a system. Unfortunately, I have yet to find a comparable single-point information source for other intrusion detection systems. One point in favor of a video surveillance system is that it provides a video record of the alarm situation. This frequently allows for a rapid determination of most false positives. This reduces the need for sending someone to the site of the alarm for investigation purposes. This is one of the reasons that video systems, without the analytics software, are used as a backstop for other IDS systems. Recommendation This short article by Nick Grange is certainly worth the time to read it. It will not make anyone a video analytics integrator by any means. It will, however, provide some additional information that will allow a facility security officer to be a more intelligent consumer of security services. While you’re there on the site, you might as well browse through the other offerings on John’s web site.