Despite substantial technological advancements, the comprehensive mapping of surface water, particularly smaller bodies (<1ha), continues to be a challenge due to a lack of robust, scalable methods. Standard methods require either training labels or site-specific parameter tuning, which complicates automated mapping and introduces biases related to training data and parameters. The reliance on water's reflectance properties, including LiDAR intensity, further complicates the matter, as higher-resolution images inherently produce more noise. To mitigate these difficulties, we propose a unique method that focuses on the geometric characteristics of water instead of its variable reflectance properties. Unlike preceding approaches, our approach relies entirely on 3D coordinate observations from airborne LiDAR data, taking advantage of the principle that connected surface water remains flat due to gravity. By harnessing this natural law in conjunction with connectivity, our method can accurately and scalably identify small water bodies, eliminating the need for training labels or repetitive parameter tuning. Consequently, our approach enables the creation of comprehensive 3D topographic maps that include both water and terrain, all performed in an unsupervised manner using only airborne laser scanning data, potentially enhancing the process of generating reliable 3D topographic maps. We validated our method across extensive and diverse landscapes, while comparing it to highly competitive Normalized Difference Water Index (NDWI)-based methods and assessing it using a reference surface water map. In conclusion, our method offers a new approach to address persistent difficulties in robust, scalable surface water mapping and 3D topographic mapping, using solely airborne LiDAR data.

翻译：尽管技术取得了显著进步，但由于缺乏稳健且可扩展的方法，地表水体（尤其是面积小于1公顷的小型水体）的全面测绘仍然是一项挑战。标准方法需要训练标签或特定地点的参数调整，这使自动化制图复杂化，并引入了与训练数据和参数相关的偏差。对水体反射特性（包括激光雷达强度）的依赖进一步增加了问题复杂性，因为更高分辨率的图像本质上会产生更多噪声。为解决这些难题，我们提出了一种独特方法，该方法聚焦于水体的几何特征而非其多变的反射特性。与以往方法不同，我们的方法完全依赖于机载激光雷达数据的三维坐标观测值，利用了连通地表水体因重力作用保持平坦的原理。通过结合这一自然规律与连通性，我们的方法能够准确且可扩展地识别小型水体，无需训练标签或重复参数调整。因此，该方法能够生成包含水体与地形的完整三维地形图，整个过程仅使用机载激光扫描数据以无监督方式完成，从而可能提升可靠三维地形图的生成流程。我们在广泛多样的景观中验证了该方法，同时将其与具有高度竞争力的归一化差异水体指数（NDWI）方法进行比较，并使用参考地表水体图进行评估。总之，我们的方法为仅利用机载激光雷达数据解决稳健、可扩展的地表水体制图及三维地形制图中的持续难题提供了新的途径。