基于三维模型重构技术的公路预制构件尺寸检验评价方法

为使公路工程异形混凝土预制构件的制造尺寸检验评价适应工业化建造要求，应用三维模型重构技术检验评价了异形混凝土预制构件尺寸，提出了高精度、自动化异形混凝土预制构件尺寸检验评价方法，包括三维模型重构、点云数据处理和检验评价体系3个环节；总结了基于三维摄影的点云模型重构技术的原理和关键环节，研究了基于坐标转换和包围盒的无关点云自动剔除算法，并通过2个实例验证了该算法的效果；研究了点云整体配准和3类局部配准方法，针对不同形状的构件和不同位置的细部构造，结合工程需求进行对照；考虑工程需求并与配准方法对应，提出了基于彩色误差云图和数理统计方法进行构件尺寸检验评价的3种判异原则，包括误差均值和标准差判异原则、误差极值判异原则、综合判异原则；综合分析彩色误差云图和误差分布，利用判异原则对箱型涵洞侧墙和管型涵洞侧墙实例的尺寸进行了检验评价。研究结果表明：3种判异原则分别适合对预制构件进行整体宏观、局部单项和先整体后局部的检验评价；采用三维模型重构技术建立的异形混凝土预制构件点云模型，与实际构件相比其长度和宽度的误差均值约为1.5 mm，三维模型重构技术可以替代人工测量；能够自动化剔除无关点云，并执行更为严格且符合工程需求的构件尺寸检验评价。

Dimensional inspection and evaluation method of highway prefabricated components based on 3D model reconstruction technology

To adapt the manufacturing dimensional inspection and evaluation of special-shaped concrete prefabricated components of highway engineering to the requirements of industrialized construction, the 3D model reconstruction technology was used to inspect and evaluate the dimensions of special-shaped concrete prefabricated components. A high-precision and automated method of the dimensional inspection and evaluation on special-shaped concrete prefabricated components was proposed, including three steps as 3D model reconstruction, point cloud data processing, and inspection and evaluation system. Principles and key links of point cloud model reconstruction technology based on the 3D photography were summarized. An algorithm of automatically eliminating irrelevant point clouds based on the coordinate transformation and bounding box was studied, and the effectiveness of this algorithm was validated using two case examples. The global point cloud registration and three local registration methods were studied. The detailed structures of components with different shapes and different positions were combined with engineering requirements for comparison. Considering the engineering requirements and the correspondence of registration method, three discriminant principles were proposed for the component dimensional inspection based on the color error nephogram and mathematical statistics method, including the discriminant principle based on mean and standard deviation of error, discriminant principle based on extreme value of error and comprehensive discrimination. The dimensions of a box culvert side wall and a pipe culvert side wall were inspected and evaluated by using these discriminant principles, based on comprehensive analysis of color error nephograms and error distributions. Research result shows that the three different discriminant principles are respectively suitable for the global, local, and global at first and then local inspections and evaluations of prefabricated components. Compared with the actual component, the average dimensional errors of length and width in the point cloud model of special-shaped concrete prefabricated component established by the 3D model reconstruction technology are about 1.5 mm. The 3D model reconstruction technology can replace the manual measurement method, can automatically eliminate irrelevant point clouds, and can facilitate a more stringent component dimensional inspection and evaluation meeting engineering requirements. 2 tabs, 16 figs, 31 refs.