Achieving Perimeter Security Detection Accuracy
Perimeter security cameras that use video analytics are designed to detect movement, but outdoors, everything moves. Trees and foliage, small animals, and blowing debris can overload security operators with nuisance alerts and undermine trust in the system.
The foundation to accurate detection outdoors is to know the location of a detected object so its size can be determined. This is done with cameras that are calibrated to GPS coordinates of the scene. Such “GPS Analytics” are used for accurate size filters that eliminate movement which does not represent a security concern – like small animals or blowing debris – while detecting human-sized intruders under all conditions.
Accurate size filters are particularly important over expansive areas typical of site perimeters, where small objects close to the camera will look much larger than a person moving off in the distance. For example, a dog at 30 meters from the camera will look much larger than a man at 300 meters from the camera, as you can see in the image below.
A smart camera needs to ignore the dog at right while alerting on the distant person, even though the dog will cover more of the camera’s field of view. Obviously, dogs are not a common perimeter security problem, but blowing trash, birds and small animals, moving clouds, and other moving things are always present the outdoors.
The key is to use cameras that are geo-registered to the scene, so every object’s location and size will be known. Geo-registration also enables a three-dimensional capability for the smart camera to determine the actual size of a moving object anywhere in the field of view. Accordingly, cameras that are geo-registered will detect man-sized objects anywhere within their field of view, and ignore small animals, blowing trash or debris whether near or far from the camera.
Geo-registration provides a number of additional benefits, including the ability to auto-steer PTZ cameras to an alarm’s precise location, and to display detected targets onto a sitemap of the facility to follow an intrusion in real time.