3D Multi-view Stereo Modelling of an Open Mine Pit Using a Lightweight UAV

Digital elevation models have been evolved in decades, their resolution and accuracy have improved  vividly. Geological, structural and geomorphological benefits of those high-quality digital elevation models enhanced  the quality of the research and engineering and unfold the visibility of the data. Modern techniques such as laser  scanners provide a quantum leap on digital modelling, however the cost of those methods limits their widespread  usage. Improvements in stereo-photogrammetry did not decelerate. On the contrary, the evolution of Structure from  Motion–Multi-view stereo-photogrammetry (SfM-MVS) method is accelerated by the continuous developments in  digital photography and computer vision technologies. We have used a lightweight drone to acquire digital aerial  photographs of an open mine pit for an ultimate purpose of modelling the terrain using SfM-MVS procedure. We  have been able to derive a high resolution (0.3 m/pixel) DEM and a very high resolution (0.04 m/pixel) orthorectified  aerial image. Both datasets are representing the topography with high sample point densities. Elevation model dataset  has been compared with the regular topographic point measurements of the mine pit and the accuracy of the aerially  derived model have been investigated. Sources of modelling errors, the effect of temporal physical changes in the  terrain, effect and importance of geo-referencing have been discussed in detail. SfM-MVS is a cost-effective, rapid  and promising technique for digital mapping, modelling and monitoring in various spatial scales of Geology.