Passive Visible Light Detection of Humans

Abstract

This paper experimentally investigates passive human visible light sensing (VLS). A passive VLS system is tested consisting of one light emitting diode (LED) and one photodiode-based receiver, both ceiling-mounted. There is no line of sight between the LED and the receiver, so only reflected light can be considered. The influence of a human is investigated based on the received signal strength (RSS) values of the reflections of ambient light at the photodiode. Depending on the situation, this influence can reach up to ± 50 % . The experimental results show the influence of three various clothing colors, four different walking directions and four different layouts. Based on the obtained results, a human pass-by detection system is proposed and tested. The system achieves a detection rate of 100% in a controlled environment for 21 experiments. For a realistic corridor experiment, the system keeps its detection rate of 100% for 19 experiments.

Identification and Speed Estimation of a Moving Object in an Indoor Application Based on Visible Light Sensing of Retroreflective Foils

“…The technology of VLS is more or less a general term describing various tasks on the basis of extracting information from the received light intensities and in some cases from the spectral composition of the light at a photosensitive device. The applications range from occupancy or presence detection [ 16 , 17 ], identification [ 18 ], pose detection [ 19 ] to gesture recognition [ 20 ]. Similar to this broad range of applications, the applied devices, the orientations of the light sources and the receivers in relation to each other and the used algorithms also vary largely.…”

Machine Learning Assisted Visible Light Sensing of the Rotation of a Robotic Arm

“…To extend the potentials of VLS, these surfaces can be coated with codes, this means sequences of surface areas with different reflectivity values or different colors, which supports the identification of an object, its positon or a movement of the object [14] [15]. Applications of VLS range from presence detection [16], pose detection [17] occupancy estimation [18], and hand gesture recognition [19] [20] to vital sign monitoring [21]. Especially in scenarios in which human beings are involved, VLS has the advantage that it does not provide privacy concerns.…”

Backscattered Visible Light Sensing of Retroreflective Foils Utilizing Random Forest Based Classification for Speed and Movement Direction Determination and Identification of an Indoor Moving Object

“…The line-of-sight in this regard is understood as the straight line between the light source(s) (transmitter) and the photosensitive device(s) (receiver) [7,10]; therefore, non-lineof-sight systems are considered systems in which the light emitted from the light source is not received at the photosensitive device without being reflected at least once.…”

“…In ref. [10], it is shown how humans can be detected by means of backscattered visible light sensing, without the necessity of placing markers or distinct materials on the persons. In the presented non-line-of-sight scenarios, the authors investigated not only the effects of different clothing materials and colors, but also showed in a so-called pass-by experiment in a corridor that the task of presence detection can be very well performed by VLS utilizing only a single photodiode as the receiving element.…”

“…Nevertheless, ref. [10] outlines an interesting future research direction, where the materials and maybe shapes of objects are used to perform in-depth sensing tasks, without the need of distinct markers.…”