*Perimeter Intrusion Detection

By Tom Polman
3 min

Technical Article | TA-20201002-TP-15

VDG Sense | Video Content Analyses | ObjectR Advanced

There are many high level security and surveillance situations that require continuous perimeter observation. In many cases, the premises protected are large and difficult to oversee, such as power plants, refineries, and military bases. ObjectR Advanced contains the function of Perimeter Intrusion Detection (PID), providing a solution for (large) perimeter video security, helping the security officer to focus on the video streams where his attention is needed. ObjectR Advanced is able to identify the tiniest changes in a scene with the lowest possible false-alarm rate. In this article we will focus on the function Virtual Fencing.

Virtual Fencing

This is a technique that uses a virtual fence in the camera’s image to generate alarms. A virtual fence is a drawn line in the image itself. When an object crosses or touches this line it triggers an alarm. This is mainly used in combination with a real fence, to give an alarm when someone climbs over or cuts his way through this fence and tries to enter the restricted area. Virtual Zones could also be applied, where an alarm is triggered when someone resides within a defined zone for a certain amount of time. For example when this person stays within the vicinity of a fence for a suspicious long period of time.

The possible scenario of someone trying to enter a restricted area and passing a virtual fence could trigger the following actions:

  • The security officer / operator is informed about the camera image, by displaying a large image of the camera stream on screen and / or sending out an alarm.

  • A PTZ camera could be shifted to a defined preset to focus on the area.

  • Extra lights shining on the area are turned on.

  • The event is automatically stored to be easily retrieved for research on a later moment.

In this case, the following rules should be defined in VDG Sense ObjectR:

Lines:
Generate alarm when an object touches or crosses a drawn line.

Zones:
Generate event when an object enters, exits a defined zone, and trigger alarm when an object resides there for a certain amount of time.

Filter Possibilities

Virtual Fencing is a technique that is mainly used outdoors. Weather influences, an unstable environment or other external factors can cause unwanted alarms. There are various filter possibilities available to reduce these to a minimum. For instance, you can filter out small objects, to make sure only objects of a certain size can cause an alarm. Another possibility is to filter on objects being in the image for a minimal amount of time before it can trigger an alarm, for instance to filter out fast moving objects.

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