Terrestrial laser scanner and retro-reflective targets: an experiment for anomalous effects investigation

摘要: Artificial targets are generally used in terrestrial laser scanner (TLS) practice for data georeferencing. This is because they well recognized and modelled from the point cloud their positions can be contemporarily measured by topographical techniques. The accuracy of target identification directly influences georeferencing quality. In particular, retro-reflective materials cause anomalies range measurement due to too high amplitude returned pulse. If received pulse intensity exceeds limits sensor dynamic range, receiver saturates, producing a truncated preventing correct time-of-flight computation. A series experiments was performed order test performances specific instrument (Optech ILRIS 3D) acquisition artificial made material, resulting very reflectance. Dealing with ranges lower than about 300 m, two cases were clearly observed: wrong distance points over reflecting surfaces presence haloes around these surfaces. Neglecting phenomena has serious implications lead Experiments executed analysed, providing qualitative semi-quantitative phenomenon description. Finally, design that easily correctly proposed.