I. Introduction
Camera traps are widely used in wildlife research, conservation and photography as well as in smart buildings, e.g. for people counting [1]–[3]. When a living being is in front of the camera trap, it triggers a high-resolution camera. The detection of the living being can be based on different technologies. Passive infrared (PIR) sensors are often used for presence detection of people and wildlife [4]–[6]. But the detection reliability by using camera traps with a PIR sensor is very sensitive to their placement [6]. Also, the sensitivity of PIR sensors is usually very high, resulting in an unwanted high false positive (FP) rate [7]. The presence detection can also be based on radar sensors [8]. The use of radar sensors in wildlife monitoring typically results in a lot of FP when there is wind or rain [9]. By using infrared light barriers to detect living beings, a detection occurs when the light barrier is crossed, limiting the camera's triggering to a very limited space [10].