Beaches are characterized by high morphodynamic activity, and high-frequency measurements are needed to understand their states and rates of change. Ideally, beach survey methods should be at once accurate, rapid and low-cost. Recently, unmanned aerial systems (drones) have been increasingly utilized to measure beach topography. In this paper, we present a review of the state of art in drones and photogrammetry for beach surveys and the respective achieved measurement quality (where reported). We then show how drones with a minimal configuration and a low-cost setup can meet the high accuracy and rapidity required for beach surveys. To test a minimal drone and ground control point configuration, we used consumer-grade equipment to perform the same flight path with different cameras and at different altitudes. We then used photogrammetry to produce digital elevation models of the beach. Using a GNSS-RTK system, we collected 2950 independent control points to evaluate the accuracy of the digital elevation models. Results show that, once a few potential sources of uncertainties in the final digital elevation model are taken into account, the average RMSE(z) of the digital elevation models was ~5 cm, with a survey efficiency of ca. 3 m 2 min −1 . Digital elevation models taken at different times were used to calculate the before–after sediment budget following a storm that hit a sandy coast in Sylt Island at the German North Sea coast.

中文翻译：

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无人机与摄影测量法测量沙滩地形精度

海滩的特点是高度的形态动力学活动，需要高频测量来了解它们的状态和变化率。理想情况下，海滩调查方法应该同时准确、快速和低成本。最近，越来越多地利用无人机系统（无人机）来测量海滩地形。在本文中，我们回顾了无人机和用于海滩调查的摄影测量的最新技术以及各自实现的测量质量（在报告中）。然后，我们展示了具有最小配置和低成本设置的无人机如何满足海滩调查所需的高精度和快速性。为了测试最小的无人机和地面控制点配置，我们使用消费级设备在不同的相机和不同的高度执行相同的飞行路径。然后我们使用摄影测量法来制作海滩的数字高程模型。使用 GNSS-RTK 系统，我们收集了 2950 个独立控制点来评估数字高程模型的准确性。结果表明，一旦考虑到最终数字高程模型中一些潜在的不确定性来源，数字高程模型的平均 RMSE(z) 约为 5 cm，调查效率约为 5 cm。3 m 2 min -1 。在风暴袭击德国北海沿岸叙尔特岛的沙质海岸之后，使用在不同时间拍摄的数字高程模型来计算前后沉积物预算。一旦将最终数字高程模型中的一些潜在不确定性来源考虑在内，数字高程模型的平均 RMSE(z) 约为 5 cm，调查效率约为 5 cm。3 m 2 min -1 。在风暴袭击德国北海沿岸叙尔特岛的沙质海岸之后，使用在不同时间拍摄的数字高程模型来计算前后沉积物预算。一旦将最终数字高程模型中的一些潜在不确定性来源考虑在内，数字高程模型的平均 RMSE(z) 约为 5 cm，调查效率约为 5 cm。3 m 2 min -1 。在风暴袭击德国北海沿岸叙尔特岛的沙质海岸之后，使用在不同时间拍摄的数字高程模型来计算前后沉积物预算。