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

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.