Establishing an image-based ground truth for validation of sensor data-based room occupancy detection

Abstract

Occupancy controlled heating, ventilation and air condition in offices are a mean to avoid energy waste due to over-conditioning of rooms. Occupancy detection methods based on sensor data that is already available in a building for other reasons than occupancy detection are therefore of great interest. However, such methods need to be validated according to a ground truth. This paper presents an image-based method for automatic establishment of a reliable and anonymous ground truth at entrance areas where the room height only allow the camera to be installed at 2.3–3.0m above the floor. The method deploys various image processing techniques to infrared depthframe images recorded with a ceiling-mounted Kinect camera to anonymously detect and track persons entering or leaving a room and, consequently, counting the number of occupants in the room. The method demonstrated an accuracy of more than 98% in a stress test, 100% in a range of relevant function test and 99% in a three week long room occupancy test.