A New Approach to Identify On-Ground Lamp Types from Night-Time ISS Images

Natalia Rybnikova,Anna Brook,Alejandro Sánchez De Miguel,Sviatoslav Rybnikov

doi:10.3390/rs13214413

Natalia Rybnikova, Anna Brook + Show 2 more

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https://doi.org/10.3390/rs13214413

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Abstract

Artificial night-time light (NTL), emitted by various on-ground human activities, has become intensive in many regions worldwide. Its adverse effects on human and ecosystem health crucially depend on the light spectrum, making the remote discrimination between different lamp types a highly important task. However, such studies remain extremely limited, and none of them exploit freely available satellite imagery. In the present analysis, the possibility to remotely assess the relative contribution of different lamp types into outdoor lighting is tested. For this sake, we match two data sources: (i) the radiometrically calibrated RGB image provided by the ISS (coarse spectral resolution data), and (ii) a set of in situ measurements with detailed spectral signatures conducted by ourselves (fine spectral resolution data). First, we analyze the fine spectral resolution data: using spectral signatures of standard lamp types from the LICA UCM library as endmembers, we perform an unmixing analysis upon NTL in situ measurements; by this, we obtain the estimates for relative contributions of the standard lamp types in each examined in situ measurement. Afterward, we focus on the coarse spectral resolution data: by using various types of statistical models, we predict the estimated relative contributions of each lamp type via RGB characteristics of spatially corresponding pixels of the ISS image. The built models predict sufficiently well (with R2 reaching ~0.87) the contributions of two standard lamp types: high-pressure sodium (HPS) and metal-halide (MH) lamps, the most widespread lamp types in the study area (Haifa, Israel). The restored map for HPS allocation demonstrates high concordance with the network of municipal roads, while that for MH shows notable coincidence with the industrial facilities and the airport.

Highlights

For the study area of Haifa, Israel, we match two night-time light (NTL) data sources: (i) the radiometrically calibrated RGB image provided by the ISS, and (ii) a set of in situ measurements with detailed spectral signatures conducted by ourselves
Among all initially available in situ measurements, we chose only the set of representative measurements—those deviating from the corresponding pixels of the radiometrically calibrated ISS image by less than 0.2 in terms of the Euclidian distance in the G/R, B/G
We tested for the possibility to identify on-ground lamp types from freely available satellite imagery of relatively coarse spatial and spectral resolution

Summary

Introduction

Artificial night-time light (NTL), emitted by various on-ground human activities, becomes further intensive in many countries, making the world brighter [1,2,3]. There exist vast inequalities in the spatial distribution of NTL intensities: night light flux per capita in the USA on average is three times more than in Europe; across US counties, there exists a 16,000-fold difference between the most and the least light-polluted ones [4]. The most polluted countries (in terms of the populations living under polluted skies) are Saudi Arabia, South Korea, Argentina, Canada, Spain, the US, Brazil, Russia, Japan, and Italy [3]. Dynamics of NTL levels might be used for Remote Sens.

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