Flight line planning is the first step in an aerial photography campaign. Its two key parameters, ground sampling distance (GSD), and overlap should be designed carefully as they will impact subsequent flying workload and even the final mapping accuracy. For a flat terrain region, flight line planning is easy using a traditional method with fixed baseline, flight spacing, and flight altitude. But for a steep terrain region, photo overlap and GSD will change greatly with topography, and thus a flight line planning using the traditional method is not sufficient. This article presents a novel adaptable flight line planning method for frame camera with four application modes. The flight line planning procedure is implemented through rigorous imaging geometry model using digital elevation data, where actual overlap and GSD can be calculated precisely. Using the desired overlap and GSD as constraint conditions, the flight spacing, baseline, and flight altitude can be adjusted adaptively according to ground topography. To assess the effect, a hypothetical test in a rugged terrain region was conducted to compare the project workload, GSD, and overlap of the four modes. The results show that Mode 2, Mode 3, and Mode 4 can realize better overlap with lower workload than the traditional method Mode 1. Mode 3 and Mode 4 have better GSD distribution than Mode 1 and Mode 2. The Mode 3 method was also validated in an actual project, showing a favorable performance in final reality 3D model result.

中文翻译：

---

使用 DEM 进行机载摄影测量的适应性航线规划


飞行路线规划是航拍活动的第一步。地面采样距离（GSD）和重叠度这两个关键参数需要仔细设计，因为它们会影响后续的飞行工作量，甚至最终的测绘精度。对于地形平坦的地区，使用固定基线、飞行间距和飞行高度的传统方法很容易规划航线。但对于地形陡峭的地区，照片重叠和GSD会随着地形的变化而发生很大的变化，因此使用传统方法进行航线规划是不够的。本文提出了一种新颖的具有四种应用模式的帧相机自适应航线规划方法。航线规划程序是通过使用数字高程数据的严格成像几何模型来实现的，可以精确计算实际重叠和GSD。以期望的重叠和GSD作为约束条件，可以根据地面地形自适应调整飞行间距、基线和飞行高度。为了评估效果，在崎岖地形区域进行了假设测试，以比较项目工作量、GSD 和四种模式的重叠。结果表明，与传统方法模式1相比，模式2、模式3和模式4能够以更低的工作量实现更好的重叠。模式3和模式4比模式1和模式2具有更好的GSD分布。模式3方法也得到了验证。在实际项目中，最终的现实3D模型结果表现出了良好的表现。