Creating a digital twin from the skies keeps construction on track

Author: Anne Pitkaenen

Construction company Stricker leverages aerial reality capture data from monthly flights, saving project time and keeping the survey team safe.

Fourty kilometres North of Cologne in Germany you find the city of Hückeswagen, where construction of a new business park - Industrial Park West III - began in 2019. Spanning an area of 145,000 square metres, what was once a fairly steep green meadow is being transformed with the help of construction company, Stricker.

Before building work could begin, approximately 25,000 cubic metres of topsoil had to be removed and recycled. Overall, 230,000 m³ of ground had to be levelled and prepared for drainage and new road construction. In projects of this scale, using aerial survey equipment such as an Unmanned Aerial Vehicle (UAV) can be a strategic advantage for the survey team, compared to traditional surveying methods. Safety is improved, as the UAV surveyor does not need to enter the active construction site, keeping away from possible danger. In addition, the construction site activities can continue without interruption caused by surveying. This keeps the site productive while having up-to-date as-built data.

Survey-grade data you can trust 

Stricker’s survey team were tasked with not only monitoring the progress of the project on a monthly basis but also providing volume calculations and documentation to the wider project team. Knowing that stockpiles are not typically well measured by conventional survey instruments - they are hard to access or there are too many variations in the height - the team opted for surveying with a UAV. 

At first, they used a prosumer-grade UAV, but found that it was not able to provide the accuracy required. Recognising the clear benefits of surveying with a UAV, the team set out to find a more reliable and accurate solution. Having used Leica Geosystems survey tools on site anyway, such as Leica iCON solution with Leica iCON gps 60 GNSS and Leica iCON robot 50 total station and Leica Rugby solutions, for many years, the Stricker team selected the Leica Aibot AX20 UAV platform. 

They fly over the whole construction area each month, which enables them to compare the digital twin data from month to month to ensure the project is proceeding as planned. The point cloud data capture from the Aibot is used for terrain profiles and volume calculations.

“First we were convinced that having a UAV for surveying would be beneficial for us. After using another solution, we realised that we needed a surveying UAV to achieve the accuracy, efficiency and safety our projects need. We chose Aibot because of that, and we are pleased with the results we get and are using it now in many of our projects” says Michael Schwarzkopf, Diplom-Ingenieur and a surveyor at Stricker.

Data collection from above

To keep line of sight and ensure data quality when surveying such a large construction site, the pilots needed to plan the surveying missions from several locations. Using the fight planning software for Leica Aibot, the team were able to confirm that just four flights were needed in total to capture the entire site due to the coverage achievable with the AX20. During the first survey, the weather was poor. It rained and became very dark, but the Leica Aibot was still able to return quality data so the team could continue despite the bad weather conditions and completed the flights as planned.

During the four flights, Aibot automatically collects 42-megapixel photos, as well as detailed flight and location information. To achieve the best quality, HxGN SmartNet is used for GNSS corrections, and the data is then processed in Leica Infinity software to produce a point cloud, orthophotos and a digital terrain model. The resulted accuracy of the entire point cloud between 2-5 centimetres complies with the requirement given by the contractor. By importing the data into AutoCAD Civil3D for further processing, the team can generate volume calculations, site plans and profiles.

Schwarzkopf comments, “We need only Infinity to process all the data collected by the UAV to import into AutoCAD Civil3D; and will less time spent on site thanks to the ease and reliability of flying the Leica Aibot, we can realise time and cost savings overall.”

Pilot training

Commercial UAV pilots in Germany need a mandatory UAV pilot license - much like a driver license - known as the “Kenntnisnachweis”. In addition to that, upon purchasing the Leica Aibot, the Stricker surveyors participated in a two-day training course at Leica Geosystems UAV academy training facilities in Cologne. The training covers not only how to fly the copter, it includes full workflow training - from set-up to planning to operating and finally, data processing. After completing the training, the pilots were able to fly their first projects; and subsequently plan to train a third UAV pilot.

“We both attended the Leica Aibot training before starting our own surveying projects. After the training, we knew how to operate the system safely and efficiently and understand what matters in using a UAV for surveying,” says Lukas Vielberg, Surveying Technician at Stricker.

Since the Hückeswagen project, Stricker is now successfully using the Leica Aibot on other construction sites and for other projects and combine the data with other surveying data. With fast data collection and an easy workflow using a UAV solution, the Stricker survey team can complete their work more efficiently and safely, ultimately saving time and money across their construction projects.

Read more about Leica Aibot, Leica Infinity and HxGN SmartNet.