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Advances in cloud base height and wind speed measurement through stereophotogrammetry with low cost consumer cameras

Janeiro, F. M. ; Carretas, L. ; Kandler, K. ; Wagner, F. ; Ramos, P.M.

Measurement: Journal of the International Measurement Confederation Vol. 51, Nº , pp. 429 - 440, May, 2014.

ISSN (print): 0263-2241
ISSN (online): 0263-2241

Journal Impact Factor: 0,662 (in 2008)

Digital Object Identifier: 10.1016/j.measurement.2014.02.001

Abstract
Clouds play an important role in climate change, in the prediction of local weather and also
on aviation safety when instrument assisted flying is not available. In the case of aviation
safety, the most important parameters are the cloud base height and the amount of cloud
cover. Cloud base height can be measured by a ceilometer which, due to its relatively high
cost, is not available at many small aerodromes. Recently, a low cost solution, based in digital
photography and stereovision has been proposed. This paper describes the developed
prototype along with its measuring principle and the recent advances which include more
robust but low cost hardware, an automated calibration procedure based on photos of stars
that exhibit no parallax and an automated procedure to find the cameras orientation relative
to geographic north. Measurements of the cloud base height by the proposed system
are compared with measurements obtained by a LIDAR for validation. The wind speed and
direction relative to geographic north are also measured and compared with results from a
weather model. Finally, an uncertainty analysis of the measurement system is presented.