Photogrammetrische Beweissicherung im Zuge von Baumaßnahmen

Photogrammetric preservation of evidence in the course of construction work

DB Netz AG commissioned Mull und Partner Ingenieurgesellschaft mbH Hannover, Osnabrück branch, with the preliminary preservation of evidence for the establishment of a staging area for construction materials in the course of the line extension. The preservation of evidence included chemical/physical soil analyses as well as the overall condition survey of the area. The photogrammetric survey was carried out using aircraft technology (drone).

The approx. 65,000 m² area was systematically flown over and a total of 176 aerial photographs were taken. The level of detail was to be increased with the help of a further 59 oblique images of the dam area. The image resolution is approx. 1 pixel per cm. A coherent orthophoto was calculated from the individual photos and then a digital terrain model (DTM) was created using photogrammetric analysis.

Figure 1: Digital terrain model, ortho view, height scaling (total)

Figure 2: Digital terrain model, ortho view, height scaling (detail section)

Figure 3: Digital terrain model, oblique view of the embankment fill

With the aerial survey and photogrammetric evaluation, an orientating terrain survey for the area under consideration is carried out at the same time as the visual determination of the condition. The database thus obtained makes it easy to detect structural changes caused by construction activities or other incidents (landslides, subsidence, etc.) by means of repeat measurements. With the data generated, deviations can not only be visualised but also balanced. For example, cubature calculations and mass determinations (measurements) can be created and checked for plausibility. The use of modern flight technology in the form of drones, 3D visualisation and photogrammetric evaluation enables efficient and economical planning and monitoring of earthworks. By utilising these cost-effective methods, initial conditions, intermediate construction conditions and changes during construction can be reliably documented and calculated.

Mull und Partner Ingenieurgesellschaft mbH has extensive expertise in the practical application of geodetic data processing. Starting with digital aerial image analysis, the use of LIDAR data and recording in GIS systems through to the creation of orthophotos (aerial plans) and the derivation of precise surface models, M&P also offers on-site recording with modern aircraft and recording systems. Thanks to our many years of experience in the field of construction monitoring, we know what is important.