A Low-Resolution IR-Array as a Doorway Occupancy Counter in a Smart Building

Mika Maaspuro


A doorway counter, which detects a person underpass at a room entry/exit, may be the most accurate type of occupancy counters used in buildings. An occupancy counter, which uses a low-resolution IR-imager and   Raspberry Pi board has been constructed. The imager provides only 8 x 8 pixels initial resolution, but it has been enhanced using two-dimensional interpolation. Due to the low absolute accuracy in temperature measurements, the imager is set to measure temperature difference between a target and background. Signal-to-noise ratio is also increased using discrete two-dimensional convolution     filtering. The blob detection and tracking algorithm deduces the direction of an occupant and finally increments or decrements the counter. A heat signature varies between people and depends on person’s clothing. An on-board server on Raspberry Pi distributes the data via Wi-Fi to any client device in the net. The complete system includes also wireless PIR-sensors. The low-resolution IR   occupancy counter has been compared with counters based on different      technologies. The benefits of a low-resolution IR-imager are privacy preservation, operation capability in total darkness, energy-efficient passive operation and a low price.


occupancy counter, low-resolution IR, smart building, wireless sensor, Kal-man filter tracking, PIR-sensor, GridEye, Raspberrry Pi

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International Journal of Online and Biomedical Engineering (iJOE) – eISSN: 2626-8493
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