基于双目光栅重建和纹理映射的缺陷三维测量方法

Three-Dimensional Measurement Method of Defects Based on Binocular Grating Reconstruction and Texture Mapping

针对工业检测中对表面缺陷的高精度检测和定位需求,提出了一种缺陷特征重建方法。通过在基于双目光栅投影的三维重构系统上附加纹理相机,实现对于重构点云模型的纹理映射,并结合纹理相机图像中提取到的特征区域,完成表面特征的三维重构。针对待测物体需要进行多视角重建的情况,引入精密转台,利用旋转轴标定方法获取不同旋转位置下纹理图像与点云数据的映射关系,并利用基于距离判据的判断方法实现了对遮挡部分点云的剔除。采用四象限临近点搜索和基于距离加权平均的线性插值方法对纹理图像中像素坐标进行三维测量。实验完成了对于图像中标注缺陷轮廓内像素点的重建,实现了对于表面特征的精确尺寸计算和定位,通过对重建的缺陷尺寸和位置进行计算并与影像测量仪测得结果进行对比,可得本文方案对缺陷三维尺寸和位置的测量误差不超过0.2 mm,且能更准确地计算缺陷面积。

To meet the demand for high-precision detection and location of surface defects in industrial inspection,this paper proposes a defect feature reconstruction method.A texture camera is added to the three-dimensional(3 D)reconstruction system of binocular grating projection to realize the texture mapping of the reconstructed point cloud model.The 3 D reconstruction of surface features can be realized using the feature regions extracted from the image captured by the texture camera.Since the object needs to be reconstructed from multiple perspectives,a precision turntable is introduced.The rotation axis calibration method is used to obtain the projection relationship between the texture image and the point cloud data at different rotation positions,and the judgment method based on the distance criterion is employed to eliminate the occluded part of the point cloud.Finally,the pixel coordinates of the texture image are located in three dimensions by four-quadrant proximity search and linear interpolation based on distance weighted average.The experiments complete the reconstruction of the pixel points in the marked defect contour in the image and realize the accurate size calculation and location of surface features.The reconstructed defect size and position are calculated which are then compared with the results measured by an optical image measuring instrument.The results show that the measurement error of the proposed solution for the 3 D sizes and positions of defects is no more than 0.2 mm,and the areas of defects can be calculated more accurately.