Infrastructure Deformation monitoring – For this project a 150-year-old retaining wall along a federal road in Erlangen has to be checked for deformations, for which we carry out photogrammetric comparisons of epochs.
Integrated into the retaining wall is a monument. Therefore commemorating the construction of the Ludwig-Main-Donau (Danube) -Canal.
In addition the required accuracies in the millimeter range are achieved by a combination of tachymetric and photogrammetric methods.
The sensitivity regarding deformations is approx. 1 mm (tachymetric reference points) or 2-3 mm (photogrammetric over the entire area).
Some key points of the approach:
Placement of approx. 70 reflective markers over the entire area (length approx. 200 m, height between 5 and 12 m)
Tachymetric calibration of polygon course and reflex marker (sigma 0.7 mm)
Recording at different times by means of a lifting platform and drone
Generation of point cloud and meshes (sigma 1-2 mm)
Rejection orthophotos, resolution 2 mm
Point cloud comparisons using different algorithms
In conclusion you can download a detailed project report here.
Here are some impressions of the project:
To sum up, the Infrastructure Deformation monitoring project was excellent. Above all we had the opportunity to test our new equipment. Like our Segway. For example to get faster from A to B. Consequently, it is possible to take pictures without having to record the step movements while walking. In other words, we can work faster and more precise.
The DJI Phantom 4 Pro, released in November 2016, has a three-axis stabilized camera with a 1-inch 20 MP CMOS sensor. It upgrades its obstacle avoidance with five directional sensors. The Phantom 4 Pro offers two remote controllers, one with a dedicated screen (Phantom 4 Pro+) and one without. It integrates an upgraded Lightbridge HD video transmission system that adds 5.8 GHz transmission support and a maximum downlink video transmission range of 7 km. In addition – DJI released a set of Goggles. Which can be used with various DJI equipment, including the Phantom 4 Pro, to allow for First Person View (FPV) flying.
(FPV) also remote-person view (RPV), or simply video piloting. A method used to control a radio-controlled vehicle from the driver or pilot’s view point. To pilot a radio-controlled aircraft or other types of unmanned aerial vehicles (UAV’s). In other words you can control or steer the vehicle remotely. From a first-person perspective via an onboard camera, fed wirelessly to video FPV goggles or a video monitor. More sophisticated setups include a pan-and-tilt gimbaled camera controlled by a gyroscope sensor in the pilot’s goggles and with dual onboard cameras, enabling a true stereoscopic view.
As a result everything went smoothly and we were able to complete everything according to our schedule. To clarify, if we had not made it in time, it would have been quite expensive. Especially since we had the whole street closed for us. Likewise, in such a situation, both the road workers and surveyors must be reconvened. These unnecessary costs can be avoided with good planning and preparation. This is both in the interest of our customers and for us.
Credits and special thanks to Geospector (Stellasolar Engineering GmbH), David Mauro and Michael Radeck who brought us together.