Influence of atmospheric conditions on the range distance and number of returned points in Leica scanstation 2 point clouds

The aim of this research is to analyze experimentally the influence of atmospheric conditions on a series of measurements obtained by a terrestrial laser scanner. The scan series represents a dike covered by containers. These containers are gradually filled with water during the experiment to simulate a controlled dike collapse. From the morning of 25.09.2008 till the afternoon of 27.09.2008 two kinds of measurements were made. The first one assessed the atmospheric condition by measuring variations in radiation, temperature and humidity, which were taken as weather attributes for future analysis. The second measurements were made by the terrestrial laser scanner ScanStation 2 from Leica. During the experiment a total of 159 scans with a resolution of 5 cm on 50 m distance of the dike were made. On the scanned region twelve stable virtual targets were selected based on intensity and range. Three scan attributes were determined for each target at each of the 159 epochs: number of observed points, mean distance between scanner and target, and also standard deviation of these distances. The resulting scan attributes are compared to the 3 atmospheric attributes described above. The results indicate that scans affected by fog can be detected automatically by analyzing independent meteorological data. A weak linear relation of about 2 mm range increment per degree temperature increment at 70 m distance should be further investigated.