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For several years, photogrammetric surveys are quite often applied for surveying cultural heritage. For a detailed and accurate result, it is indispensable that the calculated point cloud represents the original geometry of the building in high quality, with vertical and horizontal structures in the same manner. Whereas many published papers in the field of digital heritage documentation are dealing with creating such models or using photogrammetric data for damage detection, only a few papers are investigating the crucial fact of accuracy and how it can be influenced by the used camera resolution. We want to present a case study, in which we compare the photogrammetric point cloud of a normal consumer drone with a high-end device. Beside the actual survey results showing the details of a Romanesque church, a statistical calculation of deviation is shown. It becomes evident that there is only a difference within some millimetres between the corresponding point clouds in most parts of the monument. Hence, it can be stated that, for most applications in heritage protection, affordable consumer unmanned aerial vehicles (UAVs) are sufficient. Only if faint details have to be resolved will a better resolution of the mounted camera be required. [ABSTRACT FROM AUTHOR]

Within this paper, a case study on the application of drone photogrammetry at the Second World War armament bunker Weingut I is presented. The aim of the project was the mapping of the preserved remains in advance to the installation of a memorial site. In particular, the preserved concrete arch and one of the ventilation shafts were mapped by this method in high quality. Therefore, even small details of the building structure as well as several damage spots needing remediation became visible. One important advantage of drone prospecting is an enhanced occupational safety and a cost and time reduction as no further manual resources are necessary. In areas without finalized clearing for Unexploded Ordnance, other manual survey method would be especially dangerous. By comparing the photogrammetric model of the bunker Weingut I with corresponding ALS Digital Surface Models (DSM) of varying resolution, the increase in information is shown. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle (UAV)‐based magnetometer systems became more and more attractive for large‐scale archaeological prospection in recent years. Although their sensors exhibit the same sensitivity than the ground‐based prospecting systems, UAV prospecting is seriously handicapped by the magnetic and mechanical disturbances of the drone and by limitations of a low‐level flight. To minimize these disturbances, scalar magnetometers are attached only on a tether 2.5–10 m beneath the drone to be flown as close as possible above the ground. First, test measurements with UAV‐fixed fluxgate magnetometers provide more accurate results than the scalar magnetometers in any configuration but have to overcome disturbance by vibrations. Here, we present a case study choosing the compact set‐up of the Sensys MagDrone R4. The high sampling rate of 200 Hz of the three axis fluxgate sensors of the R4 allows sufficient filtering of the interferences generated by the UAV and external disturbances. High‐precision flight control of the drone allows operating the sensors by radar‐controlled flight height ∼1 m above the ground, which is a fundamental and indispensable prerequisite for archaeological prospecting. For our test, we choose the site Ganacker (southern Bavaria), where we expected a large range of archaeological structures and features with high magnetic contrast. We compare and verify the magnetogram with historical and recent geodata. Our results show that the R4 system offers an outstanding step forward regarding a successful application for archaeological prospection. Already now, the system is well suited for the fast mapping of large areas and archaeological sites with intense magnetic anomalies. [ABSTRACT FROM AUTHOR]