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Author Fiorentin, P.; Bertolo, A.; Cavazzani, S.; Ortolani, S.
Title Calibration of digital compact cameras for sky quality measures Type Journal Article
Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume (up) in press Issue Pages
Keywords Skyglow; Instrumentation
Abstract This work presents the possibility of using the extremely popular compact digital cameras of smartphones or action cameras to perform sky photometry. The newest generation of these devices allows to save raw images. They are not as good as digital single-lens reflex camera, in particular in terms of sensitivity, noise and pixel depth (10 bit versus 12 bit or more), but they have the advantage of being extremely widespread on the population and relatively cheap. These economical digital compact cameras work with an electronic shutter, it overcomes the consumption of mechanics and allows to gather images for long time. The work uses a simple calibration method to transfer raw data from the proprietary RGB color space to the standard CIE 1931 color space. It allows the measurement of sky luminance in cd m−2 with an expected uncertainty of about 20%. Furthermore, the colorimetric calibration allows to know the correlated color temperature of a portion of the sky, it can help the identification of the kind of polluting sources. Aiming at better clarifying the performances of calibrated digital compact cameras, a comparison with a calibrated DSLR camera is presented in outdoor situations showing a good agreement both for luminance and color temperature measurements.
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Series Volume Series Issue Edition
ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 3063
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Author Mills, S.; Miller, S.
Title VIIRS Day/Night Band--Correcting Striping and Nonuniformity over a Very Large Dynamic Range Type Journal Article
Year 2016 Publication Journal of Imaging Abbreviated Journal J. Imaging
Volume (up) 2 Issue 1 Pages 9
Keywords Instrumentation
Abstract The Suomi National Polar-orbiting (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) measures visible and near-infrared light extending over seven orders of magnitude of dynamic range. This makes radiometric calibration difficult. We have observed that DNB imagery has striping, banding and other nonuniformities—day or night. We identified the causes as stray light, nonlinearity, detector crosstalk, hysteresis and mirror-side variation. We found that these affect both Earth-view and calibration signals. These present an obstacle to interpretation by users of DNB products. Because of the nonlinearity we chose the histogram matching destriping technique which we found is successful for daytime, twilight and nighttime scenes. Because of the very large dynamic range of the DNB, we needed to add special processes to the histogram matching to destripe all scenes, especially imagery in the twilight regions where scene illumination changes rapidly over short distances. We show that destriping aids image analysts, and makes it possible for advanced automated cloud typing algorithms. Manual or automatic identification of other features, including polar ice and gravity waves in the upper atmosphere are also discussed. In consideration of the large volume of data produced 24 h a day by the VIIRS DNB, we present methods for reducing processing time.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2313-433X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number LoNNe @ kyba @ Serial 1400
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Author Tauc, M.J.; Fristrup, K.M.; Repasky, K.S.; Shaw, J.A.
Title Field demonstration of a wing-beat modulation lidar for the 3D mapping of flying insects Type Journal Article
Year 2019 Publication OSA Continuum Abbreviated Journal OSA Continuum
Volume (up) 2 Issue 2 Pages 332
Keywords Instrumentation; Animals
Abstract We describe a wing-beat modulation lidar system designed for the 3D mapping of flying insects in ecological or entomological studies. To better understand the signals from this instrument, we analyzed simulated signals to identify how they were affected by various imperfections, such as variations in the spacing and amplitude of each individual wing-beat reflection. In addition, a radiometric model was used to estimate signal-to-noise ratio to gain insight into the relationships between the optical system design and insect parameters (e.g., wing size, reflectivity, or diffusivity).
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Series Volume Series Issue Edition
ISSN 2578-7519 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2209
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Author Downey, J.W.
Title Determination of minimum light sense and retinal dark adaptation with presentation of a new type of photometer Type Journal Article
Year 1919 Publication American Journal of Ophthalmology Abbreviated Journal
Volume (up) 2 Issue 1 Pages 13-20
Keywords Vision; Instrumentation
Abstract This paper reviews the principal hypotheses with reference to light and dark adaptation, and suggests a practical photometer, using a radioactive substance as a standard of comparison. With three illustrations, and experimental findings with this instrument.
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Notes Approved no
Call Number GFZ @ kyba @ Serial 2418
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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 (up) V-2-2020 Issue 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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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2194-9050 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 3064
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