A method to build 3D visualization model of city cloverleaf from airborne laser scanner data is presented.It is a new scheme that the method enters the modeling step after the segmentation of cloverleaf datasets.A automatic segmentation algorithm which divides the complex structure of road divaricates and cross into sections of simple construction.Then all-constraint triangulation algorithm is used to build the model of cloverleaf,the constraint section is chosen from the contour.Finally the absent parts of the data occluded by the upper structure are detected and reconstructed to get integrated 3D model of cloverleaf,it is based on the model features of sections combines with priori knowledge.The result shows the scheme can work out satisfactorily on structural complicated city cloverleaf.The analysis further explains the feasibility and efficiency.%提出一种基于机载LiDAR数据的大型立交桥建模方法。在提取立交桥数据点的基础上,采用先分割后建模策略,提出并实现立交桥结构自动分割方法,将复杂的交汇、分叉结构分割成多个结构简单的区段。在建模过程中,从轮廓中确立约束边,采用全约束三角网建模方法,建立立交桥三维可视化模型。最终利用区段建模信息结合先验知识检测并恢复被遮挡的结构,实现完整结构的真三维建模。试验结果表明,设计及流程在复杂结构立交桥的建模问题上可以取得令人满意的结果。整个模型在地理位置,几何尺寸以及拓扑关系上均与实际地物保持一致,具备三维浏览以及交互式操作的条件。对模型质量和算法效率的分析进一步说明其可行性与有效性。
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