Evaluation of the accuracy of lidar data acquired using a UAS for levee monitoring: preliminary results

This article presents the preliminary results of the possibilities for using an unmanned aerial system (UAS) for three-dimensional (3D) data collection for levees. The UAS is equipped with an ultra-light laser scanner and digital camera that acquires data with stereoscopic coverage. Sensors have beenmounted on the multi-rotor. Using such a platform allows obtaining the 3D data necessary for circular surveying works with regard to levee monitoring for the prevention of flooding. Such a platform can offer an alternative to typical direct surveying measurements performed during the monitoring of such objects. It can detect changes in the multi-temporal analysis and evaluate the condition of levees ought to continuity of surface measurement and huge density of data up to dozens points per square metre. Lidar data and images of the levees were provided for several hundred metres of test area. In presented research, several flyingmissions were carried out which provided data that allowed for an analysis presenting the influence of the technique for initial georeferencing, altitude over the terrain, scanning lines' length, overlap between scanning lines on the accuracy of relative orientation and absolute accuracy of the digital terrain model (DTM) that was created. The Iterative Closest Point algorithm and measurements of the natural and signalized control points were used to georeference and validate the lidar data obtained from the UAS. As reference data, Global Navigation Satellite System in real-time kinematic measurements was used to evaluate the absolute accuracy of the DTMs generated for the test area. The images captured from the UAS were a different data source which was checked to evaluate their usefulness in the considered application. A final accuracy close to 0.1 m was obtained for the generation of the DTM. The research proved the potential of this new kind of lidar data that can be acquired using ultra-light laser scanners.