"Testing ‘Structure-from-Motion’ photogrammetry for high-resolution topographic surveys in hydraulic laboratories"In experimental research, photogrammetric methods have been successfully used for high-resolution topographic surveys. This study discusses the performance of the fully automated photogrammetic method ‘Structure from Motion’ (SfM) for weakly-supported surfaces as well as for sediment surfaces. To evaluate the quality of the obtained SfM DEMs from different image acquisitions, we compared those DEMs with data from laser-profiling. The results show that seven images are sufficient to obtain a high-resolution SfM-DEM of a sand/gravel surface and that camera properties (such as resolution) are less important. In addition, we observe an accuracy improvement of the generated SfM-DEM for weakly-supported surfaces by using additionally a structured illumination. However, a benefit from structured illumination is only observed for a single smooth surface with a homogeneous color while no benefits are observed for sand or gravel surfaces. Nevertheless, the accuracy of topographica
l measurements for sediment surfaces demonstrates the high potential of SfM for many applications in hydraulic laboratories.