Automated Atmospheric Visibibility Measurements using a Digital Camera and Image Registration

Abstract

In this paper, a prototype for automatically measuring the atmospheric visibility using a digital camera is described. The dark object approach is used on the images obtained by the camera. In this method, two dark objects must first be identified in the images so that visibility can be derived using the modified Koschmieder formula. Due to inherent camera positioning shifts, the images are not always aligned which leads to an altered position of the chosen objects. Therefore, image registration algorithms are needed so that the atmospheric visibility can be automatically retrieved. The dark object approach and the image registration algorithms are described. Results for a clear day and for an hazy day are presented.