People counter

From Wikipedia, the free encyclopedia

A people counter is a device used to measure the number and direction of people traversing a certain passage or entrance per time unit. The resolution of the measurement is entirely dependent on the sophistication of the technology employed. The device is often used at the entrance of a building so that the total number of visitors can be recorded. Many different technologies are used in people counter devices, such as infrared beams, computer vision and thermal imaging.

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[edit] Reasons for people counting

There are various reasons for counting people, the most common of which are:

[edit] Retail Intelligence

Use of people counting systems in the retail environment is necessary to calculate the Conversion Rate, i.e. the percentage of a store's visitors that makes purchases. This is the key performance indicator of a store's performance and is far superior to traditional methods, which only take into account sales data. Traffic counts and conversion rates together tell you how you got to your sales. i.e. if year-over-year sales are down: did fewer people visit my store, or did fewer people buy? Although traffic counting is widely accepted as essential for retailers, it is estimated that less than 25% of major retailers track traffic in their stores. [1]

[edit] Planning of Staffing

Since staff requirements are often directly related to density of visitor traffic, accurate visitor counting is essential in the process of optimizing staff shifts.

[edit] Planning of Service Activities

Services such as cleaning and maintenance typically must be done when traffic is at its lowest or, occasionally, at a certain level. Planning of these activities necessitates accurate people counting.

[edit] Safety

For many locations it is essential to know how many people are inside the building at any given time, so that in the event of an evacuation they can all be accounted for. This can only be automated with the use of extremely accurate people counting systems.

[edit] Evidence of Resource Usage

Many public organizations use visitor counts as evidence when making applications for finance. In cases where tickets are not sold, such as in museums and libraries, counting is often required to be automated.

[edit] Measuring Marketing Effectiveness

Many shopping center marketing professionals rely on visitor statistics to measure their marketing. Quite often shopping center owners measure marketing effectiveness with sales. A trend has been to include visitor statistics to scientifically measure marketing effectiveness. Marketing metrics such as CPM (Cost Per Thousand) and SSF (Shoppers per Square Foot) are becoming very useful key performance indicators.

[edit] Technologies

Modern people counting systems use many different technologies, each with its own advantages and disadvantages. The main types are listed below.

[edit] Infrared Beams

The simplest form of counter is a single, horizontal infrared beam across an entrance which is typically linked to a small LCD display unit at the side of the doorway. Such a beam counts a 'tick' when the beam is broken, therefore it is normal to divide the 'ticks' by two to get visitor numbers. Dual beam units are also available from some suppliers and can provide low cost directional flow 'in' and 'out' data. Accuracy depends highly on the width of the entrance monitored and the volume of traffic.

Vertical beams are somewhat more accurate than horizontal, with accuracies of over 90% possible if the beams are very carefully placed. Typically they do not give 'in and out' information, although some directional beams do exist.

Advantages:

  • Inexpensive
  • Simple to fit

Disadvantages:

  • Most sensors are limited to non-directional counts
  • Can't discern people walking side-by-side
  • High potential to become blocked by people standing in an entrance or by merchandise or displays

[edit] Computer Vision

Computer vision represents the state-of-the-art system for people counting. These typically use either a closed-circuit television camera or IP camera to feed a signal into a computer or embedded device. Some computer vision systems have integrated links to database systems and retail point of sale systems.

Accuracy varies between systems and installations as background information needs to be digitally removed from the scene in order to recognize, track and count people. This means that CCTV based counters are vulnerable to light level changes and shadows, which can lead to inaccurate counting. If light levels are constant then high accuracy can be achieved, but counting at street level entrances, for example, can be inconsistent when sunlight shines into the view and then clouds move in front of the sun and the view then darkens. Sophisticated algorithms must be implemented to compensate for this behavior.

Advantages:

  • High accuracy, in correct conditions sometimes over 98%[citation needed]
  • Directional information
  • Flexible in customization
  • Integration with other systems

Disadvantages:

  • Higher cost than beam systems
  • Less simple implementation than beam systems
  • Accuracy can be affected by differing light levels

[edit] Thermal Imaging

Thermal imaging systems use sensors which detect heat sources, rather than using cameras as in computer vision systems. These systems are typically implemented using embedded technology.

Advantages:

  • High accuracy
  • Directional information
  • Not affected by differing light levels
  • Can count in complete darkness
  • None intrusive usually ceiling mounted

Disadvantages:

  • Higher cost than beam systems
  • Less simple implementation than beam systems

[edit] Synthetic Intelligence

This system employs multiple IR transceivers to create a count zone at ankle height. The artificial intelligence counters function in a similar way to the human brain, in other words, each event is evaluated in terms of features to determine the correct outcome i.e. count per direction. As a person passes the count zone a pattern is generated. The onboard processor extracts the features of the pattern and based on what it has been taught makes a decision regarding the event by brute force calculation.

Advantages:

  • Accuracy of 96% or higher[citation needed]
  • Directional information
  • Discriminates between human and non-human objects
  • Sensors can count in outdoor environments
  • Can count in all lighting conditions
  • Can count in complete darkness

Disadvantages:

  • Larger, more obtrusive design than other types of sensing technology.
  • High potential to become blocked by people standing in an entrance or by merchandise or displays.


[edit] References

  1. ^ HeadCount Corporation. Why Track Traffic (English). HeadCount Corporation. Retrieved on 2007-05-30.

[edit] External links