Easy to verify remotely that the counting system is working correctly.
System can be scaled up to include other areas
Privacy – people are not identified
Counts can be integrated with POS systems in real-time
Can measure dwell time and occupancy
Can generate heat maps of popular areas
Handles wide entrances and outdoor counting
Data can be made available via WiFi and the Internet-of-Things
Can be adjusted via software for individual situations – crowds, poor light, etc.
Drawbacks
Installation takes longer than for simpler systems like beam counters.
Smartphone Counting
There are several ways to count people using mobile signals. One is to collect Wi-Fi probe request signals from shoppers’ smartphones.
Advantages
Can record returning customers.
Can count inside and outside.
Can measure dwell times.
Can track people and generate heat maps of popular areas.
Drawbacks
Privacy concerns – the ethical and data protection considerations of knowing exactly how often a person returns to a location and where they went. Data collection and processing to track and understand shoppers’ behaviour likely qualifies as personal data and will come under data protection regulations with concerns about compliance with GDPR (General Data Protection Regulation).
Only counts those carrying a smart phone with Wi-Fi switched on.
As the battery of a phone gets lower, it does not send out the wi-fi probes as far or as often, making it less likely to be picked up.
With newer phone operating systems, MAC addresses are scrambled a lot more frequently, making it harder to filter out repeat counts.
Counters can also pick up signals from people that are outside the store
App Counting on Mobile Phones
Advantages
An opt-in mobile app communicates when it is approaching and inside a store.
Can record returning customers.
Can count inside and outside a store.
Can track people to generate heat maps of popular areas.
Can measure occupancy.
As it is opt-in, privacy concerns are reduced.
Wide entrances and outdoor counting covered.
Drawbacks
Data is only collected from those who have installed the app.
Counting using Wi-Fi Patterns and Signal Strengths
Uses the received signal strength of a WiFi link to estimate the number of people in the area of interest, without requiring them to carry any device like a mobile phone. The strength of the signal is first measured in the absence of people for comparison.
Advantages
No privacy issues.
98% accurate.
Will work through walls.
Drawbacks
Can only provide counts, not, for example, dwell times and heat maps.
Provides occupancy counts, not entries and exits.
Can’t verify counts.
As yet are mainly experimental systems.
Thermal Sensors
Positioned above an entrance, thermal sensors identify people by measuring their body heat.
Advantages
Quoted accuracies are between 96 and 98%.
Privacy – people are not identified .
Network together for wide areas.
Drawbacks
Accuracy can be affected by the ambient temperature within the counting area being above or below a certain value. Low ceilings can also reduce the accuracy.
Have difficulty measuring the dwell time of people.
Needs a camera or other method to verify counts.
Infra-Red Beam Systems
A sensor sends a beam to a reflector on the opposite side of the doorway. When someone passes through, the beam breaks and a person is counted. These were popular twenty years ago – now higher accuracy and more information is generally needed for most applications.
Advantages
Privacy – people are not identified.
Low cost.
Easy to install.
Can communicate with server in real-time.
Drawbacks
Accuracy tends to decrease with wide or busy entrances. Direct sunlight onto the beam will also affect the system. Difficult conditions can bring accuracy down to 80%.
Don’t measure dwell time or provide heat map data.
Needs a camera or other method to verify counts.
Turnstile
A turnstile is a kind of gate which lets one person in at a time. They provide an accurate count of entries, which is why our video people counting product is called “Video Turnstile”. Drop Arm Optical Turnstiles are beam counters which raise a mechanical arm to let people through.
Advantages
Extremely accurate.
Good where security is needed.
Disadvantages
Not suitable for shops and areas where easy access is needed.
Dwell times and heat maps not available.
Manual Counts
Hand-held tally counters are the least sophisticated of solutions. A person stands clicking the tally counter whenever anyone passes through the entrance. This may be acceptable for a one-off people counting excercise, but is obviously unsuited to continuous monitoring. Tally counters were once used in nightclubs and bars to monitor occupancy, but have now been replaced by automatic counting systems.
Advantages
Cheap if done on a small-scale for a short time.
Drawbacks
Accuracy varies depending on number of people entering and the person doing the counting
Verification of counts not possible unless another method is also used.
Labour-intensive.
Can’t be automatically integrated with POS system
Which people counting technology to choose?
We’ve covered a range of ways to count people. If you want more information about using cameras as part of the solution, please get in touch.
Windmill Software specialise in data acquisition and control. They publish a monthly newsletter, called Monitor, giving useful information on sensors and systems - http://www.windmill.co.uk/newsletter.html