Dronezone are builders of professional-level UAV’s and drones designed alongside their customers to meet a wide set of requirements and project needs. They equip their drones with several sensors as required by each project to meet the needs of topography, surveillance, road or traffic inspections and agricultural projects amongst others. Due to concerns about its safety and the danger from overgrown foliage, Dronezone were asked to survey the bridge to understand its structural integrity,
From a case study by OxTS.
As well as building drones for sale, Dronezone also contract out their drones and provide photogrammetry and LiDAR scanning services.
For this project, Dronezone were tasked with conducting a survey of an old railway bridge close to their headquarters in Bucharest, Romania.
What was the overall aim of the project?
Due to concerns about its safety and the danger from overgrown foliage, Dronezone were asked to survey the bridge to understand its structural integrity, whether any future restoration work was needed and if so, in what time frame. At the end of the project, Dronezone needed a clear and accurate survey of the bridge so that they could answer these questions.
To enable Dronezone to clearly demonstrate the current state of the bridge, they made the decision to conduct a LiDAR survey. LiDAR surveys involve a surveyor using a LiDAR sensor to create a 3D representation of the world around them – also known as a pointcloud.
The final pointcloud can then be used to independently navigate around the surveyed area looking for points of interest, and in this case potential weaknesses in the bridge.
To conduct an accurate scan of the bridge there were a number of factors that Dronezone had to consider. Firstly, to recreate an accurate 3D model of the bridge, they needed to ensure that every angle was surveyed. This was particularly difficult using traditional mobile mapping methods as it was important to survey the underside of the bridge and the outer faces. Furthermore, to enable full and concise diagnostics of the bridge’s condition, the pointcloud needed to be of the highest possible accuracy. OxTS UAV Bridge Survey Case Study 3 The accuracy of the navigation sensor was also an important factor to consider. The scan was to be conducted using one of Velodyne’s low resolution scanners, so the INS had to be accurate to help enhance the clarity of the final pointcloud. To ensure the best possible data is collected, the coordinate frames of the navigation (INS) and survey (LiDAR) devices had to be calibrated to the highest possible precision. Failure to measure these angles accurately enough can lead to unusable data. This is very difficult to do by eye, so another method had to be used.
The decision was made to conduct a UAV survey of the bridge using Dronezone’s DZX8 heavy drone. This decision brought about its own set of challenges including how to build a payload capable of carrying multiple sensors (INS and LiDAR) whilst ensuring it is able to continue flying long enough to conduct the required structural integrity survey.
For the complete case study CLICK HERE.
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