Intelligent Laser Trigger for Surveillance

A project with an international police force to help them with longer term surveillance was produced.  Imagine a surveillance operation where a property needs to be viewed for many weeks or days.  This could mean thousands of hours of footage being recorded and somebody having to sit through the recording to look for activity at a particular door.

Video motion detection would be impossible in the example shown as vehicles would be passing on the street between the observation window and the suspects property.

The laser acts as a very clever trigger for the recording to act as a marker.  The range to the door is measured and fixed.  If the door opens from the inside, the range increases and hence somebody is likely to be coming out.  If the range recorded by the laser is between the door distance and the garden entrance, then it is highly likely to be from a person approaching the door  Finally if the laser measures between 0 and the garden entrance distance, then this doesn’t trigger the laser as it is caused by people walking past or vehicles.

Of course if a large vehicle parks outside the suspects house, the laser will not trigger, but the camera cant see activity anyway.  A simple relay in the back of the laser was added to be a simple identifier of activity.  Hence when checking the footage, it was easy to “skip to next event” when watching the recording.