Improving vertical accuracy of UAV digital surface models by introducing terrestrial laser scans on a point-cloud level

Digital Surface Models (DSM) generated by image-based scene reconstruction from Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS)point clouds are highly distinguished in terms of resolution and accuracy. This leads to a situation where users have to choose the most beneficial product to fulfill their needs. In the current study, these techniques no longer compete but complement each other. Experiments were implemented to verify the improvement of vertical accuracy by introducing different amounts and configurations of Terrestrial Laser scans in the photogrammetric Structure from Motion (SfM) workflow for high-resolution 3D-scene reconstruction. Results show that it is possible to significantly improve (∼ 49% ) the vertical accuracy of DSMs by introducing a TLS point clouds. However, accuracy improvement is highly associated with the number of introduced Ground Control Points (GCP) in the SfM workflow procedure.