Germany – Surveying services – DGM-W Niederrhein - TLS-Messung

For the creation of a digital terrain model of the Rhine watercourse in the Lower Rhine region, a total of 48 bridges and 33 control areas are to be measured to control other laser data. These are divided into three lots by area (Lot 1 "Lower Rhine North", Lot 2 "Lower Rhine Centre" and Lot 3 "Lower Rhine South"). The areas and bridge foundation structures to be surveyed are to be captured using terrestrial laser scanning (TLS) at a specified water level. It should be emphasised at this point that the measurement of the bridge deck is not relevant and that no derived 3D model of the bridge or the bridge foundation structures is to be delivered. The survey is to be carried out by the contractor (AN) upon instruction of the contracting authority (AG). The AN must use a terrestrial laser scanner to capture the described control areas, which will serve as a reference for the quality assurance of other laser measurements. The focus is on capturing all roof areas as completely as possible, so that airborne laser scanning data can be reliably checked. Shadows on the ground or on facades caused by parked vehicles, trees, etc., are permissible, provided that sufficient ground area is still captured to ensure correct fitting and evaluation of the control areas. For each control area, at least two strategically chosen scanner positions must be set up so that their fields of view overlap and, in particular, the inclined roof areas are fully captured from different viewing angles (see Figure 1). If these two positions are not sufficient due to shadows, the number of standpoints is to be increased flexibly until complete roof coverage can be demonstrated. The measurements must be carefully recorded and georeferenced. Classification of these point clouds is not required. Outliers are to be removed. The measurements are to be carried out during the vegetation-free period (01.12.26 to 30.03.27).