People Counting

Several years ago, many shops would have infrared beams across the entrance to count the number of people passing through.  It helped managers fill in spreadsheets and get nice pretty graphs comparing sales to number of people passing through.  They range from basic (count the number of times the beam is broken and divide by two) to advanced (two beams to detect directionality and only add when the beam is broken for more than a certain time).  They were however inaccurate, and it really didn’t help when shopper’s children spent their time waving their hands infront of the beam.

In terms of surveillance, they require power and the general shop beams weren’t exactly small enough to hide and so again aren’t terribly useful.  There are however a couple of alternatives for monitoring usage of a particular building/room, depending on whether you actually own the property or not.

One client a few years ago kept having their safe cleaned out, clearly by an employee who knew how to access it.  A beeper attached to an infrared beam as described above would have been a simple device to alert people to the safe being accessed, but we wanted to covertly monitor usage.  We therefore installed a small networked webcam and configured it to record whenever activity is detected.  Unfortunately either news about the hidden camera leaked, or the culprit just moved on because the safe remained secure from then onwards.

Occasionally we want to monitor whether a particular door or gate is being used, in order to work out whether it’s safe to spend some time snooping around what’s inside.  Either a webcam or an infrared device could be used, or we could hire the opposite building/room and watch for comings and goings.  There is however a much simpler low-tech way, used mostly when we presume the owner to be unsuspecting of surveillance, it’s called a sticker.

A small sticker, advertising a charity or other worthy cause you’ve just donated to, stuck across the doorway will look as though it’s grafiti-style vandalism or simply a sticker being discarded.  What the user of the door won’t realise however, is that it’s detecting whether the door has been used between your visits.  By opening the door, the sticker gets ripped, and possibly removed.  It obviously doesn’t tell you when or who or how many people used the door, just that it has been used and that you may need to spend more time watching it.