There has been a constant increase in technology regarding unmanned aerial vehicle (UAV) systems in the last decade; yet the possibility of surveying large areas with such aerial platforms has been hampered by their low endurance. This situation has been exacerbated in low institutional capacity countries with high biodiversity coastal environments where constant monitoring is required for conservation purposes. The objective of this study was hence to determine an optimal flight mission over an initial area of 40 ha of coastal wetlands using a low-cost UAV system. The UAV missions were planned at altitudes of 60, 80, 100, and 120 m. Several orthoimages were generated with different along/across track overlaps (in intervals of 10% from 40 to 90%) in order to determine the minimum flight duration and computational efficiency. Results indicated that flight altitude and across track overlap were the most relevant variables in terms of flight distance, flight duration, number of generated images, and computer processing time. The optimal flight mission was found to be at 120-m altitude with an along/across track overlap of 60/50%. Based on the aforementioned parameters, we were able to survey a larger area of 200 ha with minimum flight duration and computer processing time. Our study highlights the feasibility and limitations of using a consumer-grade UAV in order to assess coastal wetland areas rapidly when field-based surveys approaches are not possible.

中文翻译：

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评估飞行高度和重叠对正影像生成的影响，以评估沿海湿地的无人机

在过去的十年中，有关无人机系统的技术一直在不断增加。然而，由于其耐久力低，使用这种高空平台进行大面积勘测的可能性受到了限制。在具有高生物多样性沿海环境的机构能力低下的国家，为保护目的而需要进行持续监测的情况更加恶化了这种情况。因此，本研究的目的是使用低成本的无人机系统确定沿海湿地初始面积40公顷的最佳飞行任务。无人机飞行计划在60、80、100和120 m的高度进行。为了确定最小飞行持续时间和计算效率，生成了几个具有不同沿/跨航迹重叠（从40％到90％为10％间隔）的正射影像。结果表明，在飞行距离，飞行持续时间，生成的图像数量和计算机处理时间方面，飞行高度和跨轨道重叠是最相关的变量。发现最佳飞行任务是在120米的高度，沿/跨轨道重叠率为60/50％。根据上述参数，我们能够以最小的飞行时间和计算机处理时间来调查200公顷的更大区域。我们的研究强调了在不可能进行基于实地调查的方法时，使用消费级无人机来快速评估沿海湿地地区的可行性和局限性。发现最佳飞行任务是在120米的高度，沿/跨轨道重叠率为60/50％。根据上述参数，我们能够以最小的飞行时间和计算机处理时间来调查200公顷的更大区域。我们的研究强调了在不可能进行基于实地调查的方法时，使用消费级无人机来快速评估沿海湿地地区的可行性和局限性。发现最佳飞行任务是在120米的高度，沿/跨轨道重叠率为60/50％。根据上述参数，我们能够以最小的飞行时间和计算机处理时间来调查200公顷的更大区域。我们的研究强调了在不可能进行基于实地调查的方法时，使用消费级无人机来快速评估沿海湿地地区的可行性和局限性。