An automated cloud detection method based on the green channel of total-sky visible images

Obtaining an accurate cloud-cover state is a challenging task. In the past, traditional two-dimensional red-to-blue band methods have been widely used for cloud detection in total-sky images. By analyzing the imaging principle of cameras, the green channel has been selected to replace the 2-D red-to...

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Main Authors: J. Yang, Q. Min, W. Lu, W. Yao, Y. Ma, J. Du, T. Lu, G. Liu
Format: Article
Language:English
Published: Copernicus Publications 2015-11-01
Series:Atmospheric Measurement Techniques
Online Access:http://www.atmos-meas-tech.net/8/4671/2015/amt-8-4671-2015.pdf
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author J. Yang
Q. Min
W. Lu
W. Yao
Y. Ma
J. Du
T. Lu
G. Liu
author_facet J. Yang
Q. Min
W. Lu
W. Yao
Y. Ma
J. Du
T. Lu
G. Liu
author_sort J. Yang
collection DOAJ
description Obtaining an accurate cloud-cover state is a challenging task. In the past, traditional two-dimensional red-to-blue band methods have been widely used for cloud detection in total-sky images. By analyzing the imaging principle of cameras, the green channel has been selected to replace the 2-D red-to-blue band for detecting cloud pixels from partly cloudy total-sky images in this study. The brightness distribution in a total-sky image is usually nonuniform, because of forward scattering and Mie scattering of aerosols, which results in increased detection errors in the circumsolar and near-horizon regions. This paper proposes an automatic cloud detection algorithm, "green channel background subtraction adaptive threshold" (GBSAT), which incorporates channel selection, background simulation, computation of solar mask and cloud mask, subtraction, an adaptive threshold, and binarization. Five experimental cases show that the GBSAT algorithm produces more accurate retrieval results for all these test total-sky images.
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spelling doaj.art-dd6c96e1659b430ead4ef47c9fbb30952022-12-22T02:39:39ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482015-11-018114671467910.5194/amt-8-4671-2015An automated cloud detection method based on the green channel of total-sky visible imagesJ. Yang0Q. Min1W. Lu2W. Yao3Y. Ma4J. Du5T. Lu6G. Liu7State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, ChinaAtmospheric Sciences Research Center, State University of New York, Albany, NY 12203, USAState Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, ChinaState Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, ChinaState Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, ChinaSchool of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, ChinaState Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, ChinaSmart Grid Operation Research Center, China Electric Power Research Institute, Beijing 100192, ChinaObtaining an accurate cloud-cover state is a challenging task. In the past, traditional two-dimensional red-to-blue band methods have been widely used for cloud detection in total-sky images. By analyzing the imaging principle of cameras, the green channel has been selected to replace the 2-D red-to-blue band for detecting cloud pixels from partly cloudy total-sky images in this study. The brightness distribution in a total-sky image is usually nonuniform, because of forward scattering and Mie scattering of aerosols, which results in increased detection errors in the circumsolar and near-horizon regions. This paper proposes an automatic cloud detection algorithm, "green channel background subtraction adaptive threshold" (GBSAT), which incorporates channel selection, background simulation, computation of solar mask and cloud mask, subtraction, an adaptive threshold, and binarization. Five experimental cases show that the GBSAT algorithm produces more accurate retrieval results for all these test total-sky images.http://www.atmos-meas-tech.net/8/4671/2015/amt-8-4671-2015.pdf
spellingShingle J. Yang
Q. Min
W. Lu
W. Yao
Y. Ma
J. Du
T. Lu
G. Liu
An automated cloud detection method based on the green channel of total-sky visible images
Atmospheric Measurement Techniques
title An automated cloud detection method based on the green channel of total-sky visible images
title_full An automated cloud detection method based on the green channel of total-sky visible images
title_fullStr An automated cloud detection method based on the green channel of total-sky visible images
title_full_unstemmed An automated cloud detection method based on the green channel of total-sky visible images
title_short An automated cloud detection method based on the green channel of total-sky visible images
title_sort automated cloud detection method based on the green channel of total sky visible images
url http://www.atmos-meas-tech.net/8/4671/2015/amt-8-4671-2015.pdf
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