Small-diameter pipeline panoramic measurement system based on dual-view acquisition and valid information recovery

Small-diameter pipes have been widely used in various industrial fields, but achieving imaging with both high quality and high efficiency in such a confined space remains a challenging problem. To address this issue, a visual measurement system based on a conical mirror and an object-space telecentric lens is designed and implemented. To overcome information loss caused by annular image compression and occlusion from structural support pillars, an acquisition strategy combining axial multi-frame stitching and dual-view image complementarity is proposed to acquire raw images. Together with corresponding image processing procedures, the resulting image that contains complete information about inner wall morphology is obtained. Experimental results on defect size measurement show that, compared with the ground truth, the proposed system achieves a maximum absolute deviation of 57 µm and an average absolute deviation of 34 µm. In addition, the system is applicable to inner wall topography measurement of pipes made of different materials, thereby demonstrating the engineering practicality of the proposed approach.