深孔内表面结构光图像几何畸变校正

Geometric distortion correction for structured-light image of deep-hole inner-surface

在针对深孔类零部件内表面检测过程中因曲面特性引起的结构光图像几何畸变校正问题,一直是深孔内表面检测领域的难点。本文提出了一套针对结构光条纹图像的几何校正算法:该算法首先针对无差别建模的深孔内壁模型内表面进行结构光检测;然后基于离散映射理论搭建深孔内壁模型和内壁展开模型内表面之间的几何位置对应关系;最后基于映射关系校正深孔内表面结构光图像存在的几何错位(畸变)。检测结果表明,所提算法能够有效提高几何错位的校正精度,在不考虑图像边缘的基础上,校正偏差达到亚像素水平;并且因条纹斜率不一致造成的对应条纹最大间距(即距离偏差)控制在1.5 pixel范围内,即0.135 mm。

In the detection process for the inner-surface of deep-hole parts,the correction of image geometric distortion caused by the characteristics of a curved plane has proven to be difficult.In this study,a geometric correction algorithm for structured light stripe imaging was proposed.Firstly,the deep-hole inner-surface model(DIM)obtained via undifferentiated modeling was established.Then,the geometric position correspondence relationship between the DIM and the deep-hole inner-surface plane model was established based on discrete mapping.Finally,the geometric distortion of the structured light image was corrected based on the mapping relationship.The test results indicated that the proposed algorithm can effectively improve the correction accuracy of geometric distortion to the sub-pixel level without considering the edge of the image.The maximum distance(i.e.,distance deviation)between the corresponding stripes caused by the inconsistency of the slope is the distance deviation,which was 0.135 mm less than 1.5 pixels.