Accuracy of People Counters
The quoted accuracy is how closely the measured people counts match the actual number of people entering and leaving. The best performing systems achieve over 98% accuracy.
When choosing a people counting system make sure that the accuracy quoted on the manufacturers’ web sites is not just that for perfect conditions. Will the system meet your accuracy needs in your specific environment?
The most accurate systems are the video person counters. Here software analyses CCTV pictures and detects people crossing a counting zone. These systems can exceed 98% accuracy.
Next are the thermal sensors. Positioned above an entrance, they identify people by meaasuring their body heat. Quoted accuracies are between 96 and 98%. Accuracy, though, 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.
With infra-red beam systems, a sensor sends a beam to a reflector on the the opposite side of the doorway. When someone passes through, the beam breaks and a person is counted. These were in demand some years ago – now managers generally demand a higher accuracy and more comprehensive information to be collected. Additionally, accuracy tends to decrease with wide or usy entrances. If two people cross a beam together, for instance, only one count will be recorded. Direct sunlight onto the beam will also affect the system. Difficult conditions can bring accuracy down to 80%.
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 person counting excercise, but is obviously unsuited to continuous monitoring. Accuracy depends on the people holding the tally counters. Tally counters were once used in nightclubs and bars to monitor occupancy, but are now being replaced by automatic counting systems.