| Records |
| Author |
Joachim, L.; Storch, T. |
| Title |
Cloud Detection For Night-Time Panchromatic Visible And Near-Infrared Satellite Imagery |
Type |
Journal Article |
| Year |
2020 |
Publication |
ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences |
Abbreviated Journal  |
ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci. |
| Volume |
V-2-2020 |
Issue |
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Pages |
853-860 |
| Keywords |
Instrumentation; Remote Sensing |
| Abstract |
Cloud detection for night-time panchromatic visible and near-infrared (VNIR) satellite imagery is typically performed based on synchronized observations in the thermal infrared (TIR). To be independent of TIR and to improve existing algorithms, we realize and analyze cloud detection based on VNIR only, here NPP/VIIRS/DNB observations. Using Random Forest for classifying cloud vs. clear and focusing on urban areas, we illustrate the importance of features describing a) the scattering by clouds especially over urban areas with their inhomogeneous light emissions and b) the normalized differences between Earth’s surface and cloud albedo especially in presence of Moon illumination. The analyses substantiate the influences of a) the training site and scene selections and b) the consideration of single scene or multi-temporal scene features on the results for the test sites. As test sites, diverse urban areas and the challenging land covers ocean, desert, and snow are considered. Accuracies of up to 85% are achieved for urban test sites. |
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2194-9050 |
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| Call Number |
GFZ @ kyba @ |
Serial |
3064 |
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| Author |
Alamús, R.; Bará, S.; Corbera, J.; Escofet, J.; Palà , V.; Pipia, L.; Tardà, A. |
| Title |
Ground-based hyperspectral analysis of the urban nightscape |
Type |
Journal Article |
| Year |
2017 |
Publication |
ISPRS Journal of Photogrammetry and Remote Sensing |
Abbreviated Journal |
ISPRS Journal of Photogrammetry and Remote Sensing |
| Volume |
124 |
Issue |
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Pages |
16-26 |
| Keywords |
Instrumentation; Remote Sensing |
| Abstract |
Airborne hyperspectral cameras provide the basic information to estimate the energy wasted skywards by outdoor lighting systems, as well as to locate and identify their sources. However, a complete characterization of the urban light pollution levels also requires evaluating these effects from the city dwellers standpoint, e.g. the energy waste associated to the excessive illuminance on walls and pavements, light trespass, or the luminance distributions causing potential glare, to mention but a few. On the other hand, the spectral irradiance at the entrance of the human eye is the primary input to evaluate the possible health effects associated with the exposure to artificial light at night, according to the more recent models available in the literature. In this work we demonstrate the possibility of using a hyperspectral imager (routinely used in airborne campaigns) to measure the ground-level spectral radiance of the urban nightscape and to retrieve several magnitudes of interest for light pollution studies. We also present the preliminary results from a field campaign carried out in the downtown of Barcelona. |
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| ISSN |
0924-2716 |
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LoNNe @ kyba @ |
Serial |
1613 |
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| Author |
Zheng, Q.; Weng, Q.; Wang, K. |
| Title |
Developing a new cross-sensor calibration model for DMSP-OLS and Suomi-NPP VIIRS night-light imageries |
Type |
Journal Article |
| Year |
2019 |
Publication |
ISPRS Journal of Photogrammetry and Remote Sensing |
Abbreviated Journal |
ISPRS Journal of Photogrammetry and Remote Sensing |
| Volume |
153 |
Issue |
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Pages |
36-47 |
| Keywords |
Remote Sensing; Instrumentation |
| Abstract |
Night-time light (NTL) data provides a great opportunity to monitor human activities and settlements. Currently, global-scale NTL data are acquired by two satellite sensors, i.e., DMSP-OLS and VIIRS, but the data collected by the satellites are not compatible. To address this issue, we proposed a method for generating long-term and consistent NTL data. First, a logistic model was employed to estimate and smooth the missing DMSP-OLS data. Second, the Lomb-Scargle Periodogram technique was used to statistically examine the presence of seasonality of monthly VIIRS time series. The seasonal effect, noisy and unstable observations in VIIRS were eliminated by the BFAST time-series decomposition algorithm. Then, we proposed a residuals corrected geographically weighted regression model (GWRc) to generate DMSP-like VIIRS data. A consistent NTL time series from 1996 to 2017 was formed by combining the DMSP-OLS and synthetic DMSP-like VIIRS data. Our assessment shows that the proposed GWRc model outperformed existing methods (e.g., power function model), yielding a lower regression RMSE (6.36), a significantly improved pixel-level NTL intensity consistency (SNDI = 82.73, R2 = 0.986) and provided more coherent results when used for urban area extraction. The proposed method can be used to extend NTL time series, and in conjunction with the upcoming yearly VIIRS data and Black Marble daily VIIRS data, it is possible to support long-term NTL-based studies such as monitoring light pollution in ecosystems, and mapping human activities. |
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0924-2716 |
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| Call Number |
GFZ @ kyba @ |
Serial |
2361 |
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| Author |
Bierman, A.; Figueiro, M.G.; Rea, M.S. |
| Title |
Measuring and predicting eyelid spectral transmittance |
Type |
Journal Article |
| Year |
2011 |
Publication |
Journal of Biomedical Optics |
Abbreviated Journal |
J Biomed Opt |
| Volume |
16 |
Issue |
6 |
Pages |
067011 |
| Keywords |
Instrumentation; Human Health |
| Abstract |
The purpose of the present study was to objectively quantify the spectral transmittance of the eyelid. Reported here are data acquired using a technique that was developed to provide practical and accurate measurements of eyelid transmittance across the visible portion of the electromagnetic spectrum. The empirical data were analyzed in terms of the absorption and scattering characteristics of the constituents of skin to develop a method for predicting eyelid transmission. Results showed that the eyelid has a much higher optical density at short wavelengths than previously published. The mean +/- standard deviation (s.d.) optical density of the eyelid from 450 to 650 nm was 2.1 +/- 0.3 with an optical density range among subjects of approximately 1.0. The study results indicate that skin pigmentation is poorly correlated with eyelid transmission; eyelid transmission is most affected by wavelength-independent macromolecules in the eyelid as well as its overall thickness. |
| Address |
Rensselaer Polytechnic Institute, Lighting Research Center, 21 Union Street, Troy, New York 12180, USA |
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English |
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1083-3668 |
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| Notes |
PMID:21721832 |
Approved |
no |
| Call Number |
LoNNe @ kyba @ |
Serial |
1530 |
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| Author |
Bará, S.; Escofet, J. |
| Title |
On lamps, walls, and eyes: The spectral radiance field and the evaluation of light pollution indoors |
Type |
Journal Article |
| Year |
2018 |
Publication |
Journal of Quantitative Spectroscopy and Radiative Transfer |
Abbreviated Journal |
J of Quant Spect and Rad Trans |
| Volume |
205 |
Issue |
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Pages |
267-277 |
| Keywords |
Instrumentation; Light pollution; Artificial light at night; Light field; Radiance field; Radiometry; Photometry |
| Abstract |
Light plays a key role in the regulation of different physiological processes, through several visual and non-visual retinal phototransduction channels whose basic features are being unveiled by recent research. The growing body of evidence on the significance of these effects has sparked a renewed interest in the determination of the light field at the entrance pupil of the eye in indoor spaces. Since photic interactions are strongly wavelength-dependent, a significant effort is being devoted to assess the relative merits of the spectra of the different types of light sources available for use at home and in the workplace. The spectral content of the light reaching the observer eyes in indoor spaces, however, does not depend exclusively on the sources: it is partially modulated by the spectral reflectance of the walls and surrounding surfaces, through the multiple reflections of the light beams along all possible paths from the source to the observer. This modulation can modify significantly the non-visual photic inputs that would be produced by the lamps alone, and opens the way for controlling—to a certain extent—the subject's exposure to different regions of the optical spectrum. In this work we evaluate the expected magnitude of this effect and we show that, for factorizable sources, the spectral modulation can be conveniently described in terms of a set of effective filter-like functions that provide useful insights for lighting design and light pollution assessment. The radiance field also provides a suitable bridge between indoor and outdoor light pollution studies. |
| Address |
Área de Óptica, Departamento de Física Aplicada, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es |
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| Publisher |
Elsevier |
Place of Publication |
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| Language |
English |
Summary Language |
English |
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0022-4073 |
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| Call Number |
IDA @ john @ |
Serial |
2163 |
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