一种利用机载激光点云的河流横纵断面自动提取方法

An Automatic Extraction Method of River Cross and Vertical Sections Using Airborne Laser Point Cloud

传统的河流断面测量方法具有周期长、成本高、外业多等不足,为此提出一种基于机载激光点云的河流横纵断面自动提取方法。首先,使用渐进三角网滤波器从机载点云中分离出地面点,用以构建三角网模型,并将其转化成数字高程模型数据。接着,利用洼地填充、流向分析、流量分析、河流栅格提取、矢量化等水文分析模块,从数字高程模型数据中自动提取出河流中心线。然后,修正河流中心线并生成纵断面,沿着纵断面按固定间距自动提取横断面,并自动填充属性。最后,利用断面线进行缓冲区分析,根据缓冲区范围从正射影像中裁剪出河流影像,并将河流影像与数字高程模型、横纵断面数据打包成完整成果。项目应用证明,该方法具有数据精度高、更新周期短、生产成本低等优势,适用于大范围的河流断面数据生产。

Given many disadvantages of the traditional mea-surement methods for hydraulic section, such as long period, high cost and heavy outdoor work, an automatic extraction method of river cross section and vertical section is proposed based on airborne laser point cloud. Firstly, the ground points are separated from the airborne point cloud with incremental triangulation filter to build triangulation network model and then it is transformed into the digital elevation model(DEM) data. Secondly, hydrological analysis modules such as depression filling, flow direction analysis, flow rate analysis, river grid extraction and vectorization are used to automatically extract the center line of river from DEM data. Thirdly, the center line of river is modified to generate the vertical section, and the cross section is automatically extracted with fixed spacing along the vertical section. The attri-bute values of cross section are automatically filled in. Finally, the buffer zone analysis is carried out with section lines, and the buffer zone is used to cut out the river image from the digital orthophoto map. Then, the river image is pac-kaged with DEM data, cross section and vertical section data as the final product. Project application proves that this method has the advantages of high data accuracy, short update cycle and low production cost, which is suitable for large-scale data production of hydraulic section.