EFFECTS ON THE MEASUREMENTS OF THE TERRESTRIAL LASER SCANNER HDS 6000 (LEICA) CAUSED BY DIFFERENT OBJECT MATERIALS

摘要

One of the main aspects of terrestrial laser scanning (TLS) is data quality. In the literature a lot of publications concerning this topic can be found. Several authors included also different materials into their investigations to analyse the influence on the measurements of a terrestrial laser scanner. In this paper the results of systematic test series with planar plates of different materials will be discussed. Besides targets of defined reflectivity, the choice of materials has been concentrated on those common for building facades. For quality assessment the following parameters have been selected: range correction value, standard deviation of range measurements, mean intensity value and its standard deviation. These parameters have been calculated systematically for different distances (5m to 25m), incidence angles (0~(gon) to 90~(gon)), reflectivity (5percent to 98percent) and ambient lighting and wetness conditions. The results show that the range correction value is not constant but increases with longer distances (non linear) and lower reflectivity of the surface material. The standard deviation of range measurements also increases with longer distances (about a factor of two at 25m) and reduced reflectivity (about a factor of four at 5percent) but decreases with wider incidence angles, which confirms the results of other research groups. The intensity values are quite constant for different distances but decrease with wider incidence angles. Standard deviation of intensity increases with higher reflectivity. Problems occurred with concrete (extreme variation of parameter values) and metal plates (saturation effects).