基于邻域拓扑的工程图纸三维重建

Reconstructing 3D Models from Engineering Drawings

采用基于邻域拓扑的迭代树方法对工程图纸三视图三维重建进行了研究。首先根据三维线段端点位置关系 ,提出邻域拓扑的定义 ;接着根据投影线段相对图纸坐标系存在的 5种类型 ,结合邻域拓扑定义 ,给出有效三维线段的 7种拓扑关系 ;然后将这 7种拓扑关系转变为一种迭代树方法 ,遍历二维图元得到三维线框模型 ;最后用半边结构表示面环 ,通过最大包围盒给出初始面环方向 ,由拓扑关系得到所有面内外环方向 ,装配得到平面体三维模型。本文算法能够在构建三维线框的同时排除错误的匹配边 ,可以有效地对几何基元进行重建 ,算法效率高 。

D model reconstruction is investigated from 3 orthographic engineering drawings using an iterative-tree method based on neighborhood-topology. Firstly, a definition of Neighborhood-Topology is addressed according to position relationship of 3D line segment end points; secondly, combined N-T definition with five-type projection line segments: c_1～c_5, seven-type topology valid 3D lines are enumerated; thirdly, a scheme called iterative-tree is set up based on above seven-type valid 3D lines, after traversing all branches of this iterative-tree, wireframe of 3D model is obtained; Finally, the data structure of 3D object is presented, a half-edge structure is used to express face-loop, the max-bounding box is used to find initial face-loop′s direction, all other face-loops′ directions are calculated by following topology rules and mbius rules, 3D polyhedral model is assembled. The algorithm can prompt or eliminate mismatched edges while constructing valid 3D wireframe, computational results show this algorithm is robust and effective.