The unmanned small aircraft have long since left the test phases behind. Small, light, manoeuvrable and immediately ready for use thanks to a modular system, the latest generation of multicopters and aeroplanes play an important role in the construction industry today in the course of mobile data acquisition. Thanks to their wide range of applications, drone recordings support project management and construction processes. Particularly in connection with BIM, object acquisition from the air is an important instrument in terms of data quality and regularity. However, the "flying eye" does not replace the surveyor on the construction site. Instead, drones are used as a new tool with sensor technology in various areas of surveying, billing and documentation.

From master thesis to drone team

The idea to establish an own UAV department at Max Bögl was born through contact with external service providers. They have been using the technology for some time for the preparation of as-built documents for some quarries and sand pits of our group of companies. The aerial surveys were carried out in a very short time and made available as a data set (orthophoto and point cloud or digital terrain model) - with good to impressive results. In the course of Carmen Gantert's master thesis "Use of unmanned aerial vehicles in infrastructure construction, June 2017", it was finally possible to deal more intensively with the UAV technology, the legal framework and the possible areas of application. In May 2017, the first drone, a DJI Phantom 4 Pro quadrocopter, was purchased and deployed in the BIM department. Since February 2018, Thomas Deistler has been the UAV contact under the leadership of Jan Ruschkar. Both are supported by Agata Komuda and Carmen Gantert. The "maxfly" team, as the drone flight operators call themselves, is deployed once or twice a week on various construction sites or in the factory infrastructure area. Currently, a lot of development work is still being done in order to achieve added value for the Max Bögl Group with the best possible efficiency in the future.

Extensive preparations up to deployment

Drones offer great potential for daily project work. Whether it's simple image information, vivid videos or more complex digital terrain models (DTMs): At the start of a project, the desire for more information arises on the construction site or in the project team. If this information cannot be obtained or can only be obtained very time-consuming with the available means on the construction site, the execution of a UAV flight can be used as a supplement. This is where the "maxfly" department comes in. Together with the construction site, the maxfly team uses a checklist to determine in advance whether, when and under what conditions a suitable drone flight can be realised in order to achieve the desired result. Depending on flight planning and location, this can take several days or even several weeks if official approval is required. Once all the objectives of the mission have been defined, the legal framework clarified and the weather forecasts favourable for take-off, nothing stands in the way of a drone flight.

Safe flight control with controller and iPad

First, so-called control points are laid out on site and measured with a GPS rover. These points form the basis of a georeferencing for later evaluation. Then the pre-flight check begins, in which the drone, the surroundings and the airspace are checked for their condition as well as for possible dangers and obstacles. If all the parameters are in order, the rotors, powerfully driven by DC motors, lift the Multicopter into the air with a steady whirring sound. During the flight, one of the drone operators monitors all relevant data (altitude, speed, distance, etc.) from the ground both optically via eye contact to the UAV and technically via the controller with screen. When the drone returns, the data can be read on site via a laptop with appropriate software in order to check the completeness and quality of the recording. Back in the office, the images and control point coordinates taken during the flight are merged and calculated. Depending on the amount of data, the calculation of the flight evaluation can take between hours and days. In addition, there is the time for post-processing, for example of the digital terrain model. The final result is then made available digitally to the construction site.

Outlook for new applications

For the future, the "maxfly" department wants to position itself as well as possible in the rapidly growing UAV market. The team of experts is relying on the latest recording technologies as well as more efficient evaluation processes and options for data provision in the cloud - with the aim of integrating the 3D data obtained more strongly into the company's own digitisation processes (BIM). The extended application possibilities include:

• Combination of camera and laserscan/LiDAR with one device for even more detailed data bases
• No need to set up fixed points/position marks thanks to new drone technology
• Creation of inventory models/documents
• Inspection flights with corresponding automated evaluation
• Intelligent software applications with cloud solutions
• Transport of material and equipment