三维激光扫描灰度信息在结构变形场计算中的应用

非接触测量技术是结构测量领域的最新进展之一，这类测量方法无需在被测对象上安装传感器，因而在结构试验以及土木工程现场实测中具有一定的优势。三维激光扫描作为一种非接触测量新技术，可以直接获取目标物表面点密集的三维坐标和灰度值，受测试环境干扰小，因而在土木工程领域的应用日益受到关注。在激光扫描技术的基础上，提出一种同名点的匹配方法，以提高变形场计算的精度。这种方法利用激光扫描的灰度信息，对扫描得到的点云坐标和灰度数据进行像素化处理，然后用相关系数法确定同名点并计算位移场。通过一钢梁试验对该方法进行验证，将结果与导杆位移计以及有限元分析的结果作了比对，结果显示该方法可以提高同名点识别的精度，进而提高结构变形计算的准确性，且可以同时获得构件包括平面内和平面外的变形。

Application of gray information in LiDAR scan point cloud datafor structural deformation field calculation

Noncontact sensing can obtain structural responses without the need of attaching sensors on the object, which shows great potentials in structural testing. The light detection and ranging (LiDAR) is newly developed noncontact sensor for spatial information collection. LiDAR can obtain coordinates and gray information of points on the surface of the object with little influences from testing environments. Therefore, it receives more and more attentions in civil engineering. The 3D LiDAR scan technique is introduced in this paper for structural deformation measurement. A method was developed for point identification by using gray information in point cloud data before and after deformation. Pionts from two scans are correlated by a coefficient derived from the pixelization of coordinate data and gray information. With accurate point identification, both in-plane and out-of-plane displacement fields can be calculated more precisely. This proposed method was validated through a four point bending test of steel beam. Results obtained from the LiDAR scan were compared with both the displacement transducer measurement and the results from finite element analysis, which verifies the accuracy of the method.