Evaluating Human Photoreceptoral Inputs from Night-Time Lights Using RGB Imaging Photometry

Abstract

Night-time lights interact with human physiology through different pathways starting at the retinal layers of the eye, from the signals provided by the rods, the S-, L- and M-cones, and the intrinsically photosensitive retinal ganglion cells (ipRGC). These individual photic channels combine in complex ways to modulate important physiological processes, among them the daily entrainment of the neural master oscillator that regulates circadian rhythms. Evaluating the relative excitation of each type of photoreceptor generally requires full knowledge of the spectral power distribution of the incoming light, information that is not easily available in many practical applications. One such instance is wide area sensing of public outdoor lighting; present-day radiometers onboard Earth-orbiting platforms with sufficient nighttime sensitivity are generally panchromatic and lack the required spectral discrimination capacity. In this paper we show that RGB imagery acquired with off-the-shelf digital single-lens reflex cameras (DSLR) can be a useful tool to evaluate, with reasonable accuracy and high angular resolution, the photoreceptoral inputs associated with a wide range of lamp technologies. The method is based on linear regressions of these inputs against optimum combinations of the associated R, G, and B signals, built for a large set of artificial light sources by means of synthetic photometry. Given the widespread use of RGB imaging devices, this approach is expected to facilitate the monitoring of the physiological effects of light pollution, from ground and space alike, using standard imaging technology.

Remote sensing of night lights: A review and an outlook for the future

“…The "Cities at Night" project team has occasionally produced radiance calibrated images for scientific collaborations, and a project based at the University of Exeter is currently working on a data processing pipeline to produce a public database of calibrated images. The first mosaic of high resolution ISS images was made by Schmidt (2015), covering the administrative boundaries of the country of the Netherlands, and low resolution mosaics were made using time lapses by Sánchez de Miguel and Zamorano (2012), covering large parts of the US, Europe and middle-east.…”

Mapping the Melatonin Suppression, Star Light and Induced Photosynthesis Indices with the LANcube

“…However, spectral measurements are not the easiest to obtain, especially if many of them are required. It has been shown that three bands Red, Green, Blue (RGB) photometric data can be used to determine spectral indices or photoreceptor stimuli from values recorded by a Digital single-lens reflex camera (DSLR) [17,18]. That method is much faster and easier to perform.…”

Light Pollution Monitoring and Sky Colours

“…The imagery obtained from the International Space Station is used to estimate the spectral type of ground light sources based on colour information [ 24 ]. The colour information of DSLR cameras is also used to estimate human photoreceptoral inputs based on the spectra of standard light sources [ 25 ]. There is an increasing interest in colour detection based on single detector pointing devices as well, see, e.g., [ 26 ] and the CoSQM project ( ).…”