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

Mika Maaspuro*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
156 Downloads (Pure)


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.
Original languageEnglish
Pages (from-to)4-18
Number of pages15
JournalInternational Journal of Online Engineering
Issue number6
Publication statusPublished - 28 May 2020
MoE publication typeA1 Journal article-refereed


  • Occupancy counter
  • Low-resolution IR
  • Smart building
  • Wireless sensor
  • Kalman filter tracking
  • PIR-sensor
  • GridEye
  • Raspberrry Pi


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