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19 November 2015 Method of estimation of cloud base height using ground-based digital stereophotography
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Proceedings Volume 9680, 21st International Symposium Atmospheric and Ocean Optics: Atmospheric Physics; 96804N (2015)
Event: XXI International Symposium Atmospheric and Ocean Optics. Atmospheric Physics, 2015, Tomsk, Russian Federation
Errors of the retrieval of the atmospheric composition using optical methods (DOAS et al.) are under the determining influence of the cloudiness during the measurements. Information on cloud characteristics helps to adjust the optical model of the atmosphere used to interpret the measurements and to reduce the retrieval errors are.

For the reconstruction of some geometrical characteristics of clouds a method was developed based on taking pictures of the sky by a pair of digital photo cameras and subsequent processing of the obtained sequence of stereo frames to obtain the height of the cloud base.

Since the directions of the optical axes of the stereo cameras are not exactly known, a procedure of adjusting of obtained frames was developed which use photographs of the night starry sky. In the second step, the method of the morphological analysis of images is used to determine the relative shift of the coordinates of some fragment of cloud. The shift is used to estimate the searched cloud base height.

The proposed method can be used for automatic processing of stereo data and getting the cloud base height. The report describes a mathematical model of stereophotography measurement, poses and solves the problem of adjusting of optical axes of the cameras, describes method of searching of cloud fragments at another frame by the morphological image analysis; the problem of estimating the cloud base height is formulated and solved. Theoretical investigation shows that for the stereo base of 60 m and shooting with a resolution of 1600x1200 pixels in field of view of 60° the errors do not exceed 10% for the cloud base height up to 4 km. Optimization of camera settings can farther improve the accuracy. Available for authors experimental setup with the stereo base of 17 m and a resolution of 640x480 pixels preliminary confirmed theoretical estimations of the accuracy in comparison with laser rangefinder.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Alexey I. Chulichkov, Maksim S. Andreev, Aleksandr S. Emilenko, Victor A. Ivanov, Andrey P. Medvedev, and Oleg V. Postylyakov "Method of estimation of cloud base height using ground-based digital stereophotography", Proc. SPIE 9680, 21st International Symposium Atmospheric and Ocean Optics: Atmospheric Physics, 96804N (19 November 2015);

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