The Best People Counting System?

Seven technologies to measure footfall

There are many methods of counting people, but which one is the best? A comparison of people counting technology.

Video Counting – WiFi Mobile Probes – WiFi Signal Strength – Mobile App – Thermal Sensors – Infra-Red Beam – Turnstiles – Manual

Video People Counting

Advantages

1. One of the most accurate methods at 98%.
2. Easy to verify remotely that the counting system is working correctly.
3. System can be scaled up to include other areas
4. Privacy – people are not identified
5. Counts can be integrated with POS systems in real-time
6. Can measure dwell time and occupancy
7. Can generate heat maps of popular areas
8. Handles wide entrances and outdoor counting
9. Data can be made available via WiFi and the Internet-of-Things
10. Can be adjusted via software for individual situations – crowds, poor light, etc.

Drawbacks

1. 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

1. Can record returning customers.
2. Can count inside and outside.
3. Can measure dwell times.
4. Can track people and generate heat maps of popular areas.

Drawbacks

1. 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).
2. Only counts those carrying a smart phone with Wi-Fi switched on.
3. 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. 
4. With newer phone operating systems, MAC addresses are scrambled a lot more frequently, making it harder to filter out repeat counts.
5. 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.

1. Can record returning customers.
2. Can count inside and outside a store.
3. Can track people to generate heat maps of popular areas.
4. Can measure occupancy.
5. As it is opt-in, privacy concerns are reduced.
6. Wide entrances and outdoor counting covered.

Drawbacks

1. 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

1. No privacy issues.
2. 98% accurate.
3. Will work through walls.

Drawbacks

1. Can only provide counts, not, for example, dwell times and heat maps.
2. Provides occupancy counts, not entries and exits.
3. Can’t verify counts.
4. As yet are mainly experimental systems.

Thermal Sensors

Positioned above an entrance, thermal sensors identify people by measuring their body heat.

Advantages

1. Quoted accuracies are between 96 and 98%.
2. Privacy – people are not identified .
3. Network together for wide areas.

Drawbacks

1. 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.
2. Have difficulty measuring the dwell time of people.
3. 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

1. Privacy – people are not identified.
2. Low cost.
3. Easy to install.
4. Can communicate with server in real-time.

Drawbacks

1. 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%.
2. Don’t measure dwell time or provide heat map data.
3. 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

1. Extremely accurate.
2. Good where security is needed.

Disadvantages

1. Not suitable for shops and areas where easy access is needed.
2. 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

1. Accuracy varies depending on number of people entering and the person doing the counting
2. Verification of counts not possible unless another method is also used.
3. Labour-intensive.
4. 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.

References