Sea-ice topographical measurements are valuable data for sea-ice research, monitoring and engineering design. Current sea-ice topography surveying techniques, such as ground-based surveys, aerial lidar or satellite imagery, all offer trade-offs with respect to accuracy, precision, spatial scale, spatial resolution and cost. Recent technological advancements have enabled the use of Structure-from-Motion (SfM) surveying techniques, coupled with small unmanned aerial vehicles (UAVs), as a low-cost solution for the acquisition of high-resolution topographic datasets. Here, we evaluated the potential of UAV-SfM for the topographic surveying of sea-ice, a unique and challenging environment. Field data was collected in Frobisher Bay, Nunavut, Canada, and consisted of three sUAV-SfM surveys at the sub-kilometre-level spatial scale over fast ice with multi-metre semi-diurnal tides. Using point-cloud comparisons, vertical RMSE values of 87 mm and 80 mm were obtained, respectively, from comparisons of the sUAV-SfM to a reference dataset obtained using ground surveying techniques, and from comparisons between individual sUAV-SfM surveys. The technique was successful at detecting, measuring and visualizing sea-ice topographical features, such as pressure ridges, from surveys at the sub-km spatial scale. Technical details on equipment set-up and data processing, as well as accuracy, precision and repeatability metrics are presented a resource for prospective sUAV-SfM users with an interest in the observation, monitoring or measurement of sea-ice topography. Potential end-users include sea-ice scientists and engineers, Arctic communities, ice services, polar port operators and icebreaker operators.

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Keywords Sea-ice topography, Structure-from-Motion, UAV
Conference 25th International Conference on Port and Ocean Engineering under Arctic Conditions, POAC 2019
Citation
St-Amant, M. (Martin), Mueller, D, Tivy, A. (Adrienne), & Garbo, A. (Adam). (2019). A low-cost survey method for sea ice topography using structure-from-motion photogrammetry and small uavs. In Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions, POAC.