Uncertainty modeling and simulation in terrestrial laser scanning of a slope

The simulation of Terrestrial Laser Scanner (TLS) surveys is pivotal for determining optimal instrument positions and ensuring measurement quality, especially in areas with complex morphology. The proposed simulation procedure employs a geometric model derived from Aerial Laser Scanner point clouds to estimate permissible measurement errors according to instrument specifications and scanning geometry. In terrains characterized by irregular morphology and large scanning distances, beam divergence represents a major source of error. To address this, our error model extends existing approaches by accounting for the elliptical shape of the laser beam footprint on the 3D surface, enabling the computation of the variance matrix for target coordinates in the general reference system. The variance matrix arising from beam divergence is computed for each mesh centroid in the absolute system, incorporating correlations between coordinate components induced by beam divergence and mesh orientation. Simulations were carried out to evaluate the positioning of station points and to compare expected accuracies and coverage across the test area. The most favorable results from each mesh are integrated to optimize station placement. This approach provides a more realistic assessment of TLS survey accuracy and supports improved planning and instrument selection, particularly in morphologically complex contexts such as landslide-prone slopes.