How to implement leave-behind events in C#
This article shows you how to detect objects placed in a defined zone and triggers an alarm if the object remains in the zone longer than the user-defined time allows. This is a really useful solution to avoid intentionally left baggage for public safety.
Steps of creating leave-behind events
First you have to substract the background to analyze objects in the foreground. Background subtraction is a computational vision process of extracting foreground objects in a particular scene. A foreground object can be described as an object of attention which helps to reduce the amount of data to be processed as well as provides important information to the task under consideration.
Background subtraction is a class of techniques for segmenting out objects of interest in a scene for applications such as surveillance. There are several subtraction algorithms to analyze background and foreground, for example: frame differencing, mean filter, background mixture models.
After that you must recognize and detect blobs (binary large objects) on the camera's view to create unique objects (How to implement object tracking). You should use object classification to separate desired objects such as vehicles or smaller objects (How to implement object classification).
These objects will have a dwell time, which means the length of time each object can spend in the defined zone. When an object remains in the zone longer than the user-defined time it triggers an event and you can handle this alarm by many different ways.
Why is it useful?
For example, a leave behind rule will trigger an alert when a suspicious object or bag is left on the ground. In addition, it can be used for alarm generation when an object has been left in a busy scene (such as a suitcase in an airport or railway station) being otherwise hardly notable. This feature is a key component in avoiding many possibly dangerous situations.
This functionality can also be used to detect illegal parking or vehicles staying too long in certain zones. It can also be used to search recordings for events such as parking violations and blocked freeways.
Below you can find the answers for the most frequently asked questions related to this topic:
How can I get the URL of the camera?
You can get the URL from the producer of the camera. (In the 10th tutorial you can find information on how to create an own IP camera discoverer program.)