Securing Outdoor Assets with Trusted Alerts
Safeguarding outdoor assets in a reliable and cost-effective manner often comes down to a single requirement – accurate intruder alerts and timely information about the unfolding event. While there are many technologies available for outdoor security, smart cameras with video analytics have emerged as the solution of choice for detecting intruders in real time outdoors. Yet the best technology will be handicapped if the alerts generated cannot be trusted. Repeated false alarms can eventually condition security operators to ignore real intrusions, undermining trust in the perimeter security system. In most cases the shortsighted response is to single out the security force as scapegoats, which ignores the real problem – alert fatigue. After responding to hundreds of perimeter breach alarms that turn out to be nothing more than small animals or windblown branches, even the most conscientious security guards lose confidence in the system and start to ignore its warnings. There is no longer any reason for this situation to exist. This design guide relates how smart video security technology, when properly deployed according to best practices, can cost-effectively protect outdoor assets with high accuracy and low nuisance alerts to help security forces stop intruders before they act. Start with the best detection: Use smart thermal cameras Viable outdoor security must start with a sensing system that is accurate, 24-hours per day. For this reason, conventional wisdom asserts that smart thermal cameras are the best system for detecting intruders outdoors. This is because thermal cameras see heat rather than light, so they are a perfect ‘human detector,’ and will ignore headlights, reflections off water, and other light-based activity, expanding their usefulness from their traditional role as night vision cameras to 24-hour intrusion detection solutions. Smart thermal cameras with built-in video analytic software offers several advantages: They detect in the dark with no need for costly artificial lighting. They work 24 hours/ day. They ignore reflections, shadows, moving headlights, direct sunlight, and other light-based phenomena that can trigger alarms in a visible camera detection system. Because humans give off heat, thermal sensors are far more effective in spotting a person than visible cameras. They detect body heat as far away as 600 meters – a third of a mile. A single thermal camera can protect an area the size of a football field. Proper physical design makes them immune to the effects of weather and other environmental factors. In the past, the higher price for thermal technology limited their use in commercial applications, but as costs continue to fall, many organizations are now able to choose thermal cameras as the foundation for their outdoor detection applications. Geo-registration and detection accuracy Smart thermal cameras are designed to detect movement, but outdoors, everything moves. A smart camera must be able to tell the difference between small objects such as leaves or debris and a person entering a secured area. One of the best ways for a camera to make this determination is through ‘geo-registration’ which provides the actual location and true size of all pixels in the camera’s field of view. Consider how human vision works: Our eyes give us depth perception – we can tell which object is close and which is far. But a ‘one-eyed’ camera can’t, unless it’s geo-registered. For example, a small animal near the camera will look much larger than a man at 300 meters away. (Figure 1) A smart camera needs to ignore the animal at right while alerting on the distant person, even though the animal will cover more of the camera’s field of view. The same approach applies to blowing trash, clouds, and other moving things which are always present outdoors. With a camera that is geo-registered, such non-security related movement will be ignored and will not send alarms. Essentially, geo-registration enables a three-dimensional capability for a smart thermal camera. From this information, geospatial analytic rules can be used to eliminate movement based on size while still detecting human-sized intruders under all conditions. Geo-registered analytics in action: From-to Zones Motion zones are often used by video analytic systems to detect the movement of objects and to send an alert to notify security that an intruder has been detected. By default, any object moving within a motion zone triggers an alarm. However, when used for outdoor applications, motion zones can lead to an abundance of nuisance alerts because they lack the discriminating intelligence to recognize the difference between ‘unimportant’ movement caused by the natural environment and ‘relevant’ movement that represents a security threat. Cameras that are geo-registered can create more intelligent rules called From-To Zones, an important tool for reducing nuisance alerts while maintaining a high probability of detection. Targets detected in a From-To Zone will only trigger an alarm when a specifically sized object – such as a person – moves from one zone into another defined area of the camera’s field of view. Correspondingly, objects that are not detected coming from one zone into the other are ignored. From-To Zones are a very powerful method for reducing unwarranted alarms. Importantly, they can be configured to detect zones that are geo-registered to the ground. This means From-To Zones will only alarm when a person’s feet have been in the ‘From’ and then enter the ‘To’ area, while ignoring detections that only show a part of a person such as their head. This is particularly useful when the security area includes a fence, and you only want to detect pedestrians who have crossed over the perimeter into the security zone. To see how From-To Zones work in the real world, consider an application where you need to detect pedestrians approaching the perimeter, but are not concerned about people leaving the building. With From-To Zones, the camera will only trigger an alert when intruders move towards the facility – ignoring everyone else, and greatly reducing unnecessary alarms. For another example, consider a windy perimeter around an active construction site where trash blows around the scene. Inevitably, the trash will collect along the fence and grow in size…