About Measurement of Terrain Change Using UAV at Construction Site

Abstract

At the construction site, the topography changes daily due to embankment and cut, and the amount of change is measured using surveying instruments to check the progress of construction. In the large-scale reconstruction work after the Great East Japan Earthquake, hundreds of thousands of cubic meters of earth and sand will be moved. In order to manage the process of such construction, we frequently and accurately grasp the progress with respect to the design soil volume. We used UAV photogrammetry to manage the progress of the construction site in order to accurately and easily measure the topographical changes at the construction site. In other words, by taking aerial photographs with the UAV and creating point cloud data by SfM / MVS processing, the accurate topography was grasped in a plane. By comparing the design data and the measurement data and finding the time-series change of the measurement data, it is possible to find the daily amount of earth and sand transported and the amount of work in the future. We confirmed the effectiveness of this method by applying it in the field. In addition, at such sites, the terrain will be rich in undulations as the construction of embankments and cuts progresses. Therefore, in order to keep the GSD of aerial photographs constant, we are also devising ways to control the flight altitude of the UAV. This method can be useful not only for construction work, but also for grasping changes in the ground surface after a landslide disaster and for subsequent restoration.