Simultaneous measurement of external and internal surface shape and deformation based on photogrammetry and stereo-DIC

• Published in: Optics and lasers in engineering 2022-11, Vol.158, p.107179, Article 107179
• Main Authors: Ye, Meitu, Liang, Jin, Li, Leigang, Zong, Yulong, Guo, Jianying, Tang, Zhengzong, Ma, Shikai, Chen, Renhong
• Format: Article
• Language: English
• Subjects: Coordinate alignment; Multi-view DIC; Photogrammetry; Reflection imaging; Simultaneous measurement
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2022.107179

•A systematic solution for simultaneous measurement of external and internal surface shape and deformation is proposed, in which the traditional stereo-DIC (SDIC) units are responsible for the external surface, and the reflection-assisted stereo-DIC (RSDIC) units are responsible for the internal surface; both flexible and accurate.•The structure of the RSDIC unit is proposed. Subsequently, the reflection pinhole imaging model and image correction for camera calibration are presented. The RSDIC unit can effectively deal with the measurement difficulty due to occlusion caused by the object itself and other obstacles, expanding the application range of DIC technology.•A coordinate alignment method for multi-cameras is detailed, which employs photogrammetry to reconstruct the 3D global points to solve the camera's relative parameters through resection, both robust and general for complex engineering environments.•In addition to the application in DIC technology, the structure of the RSDIC unit in the proposed system has a good reference for shape reconstruction applications such as structured light scanning in the deep hole with complex profiles. Mechanical structures with cavities such as auto rim and aero-engine casing are widely used in engineering. It is of great significance for their dynamic performance evaluation if one can measure the shape and deformation of the internal and external surfaces together. However, due to the narrow interior space and self-occlusion of complex structures, the conventional stereo-DIC unit is not applicable to impose the simultaneous measurement in the outer and inner areas. This paper is therefore concerned with a systematic solution for the issue. A reflection-assisted multi-view DIC system is configured, which consists of the stereo-DIC (SDIC) unit and the reflection-assisted stereo-DIC (RSDIC) unit. The design idea and selection essential of the RSDIC unit are stated. Subsequently, a correction model for reflection imaging is detailed. Close-range photogrammetry is specially adopted to compute the 3D global points. The extrinsic parameters of each DIC unit are estimated via the rear resection so that the individual reference frame can be transformed into a common coordinate system. Five experiments, including two tests of calibration accuracy, shape and deformation measurement accuracy, and applications in an aero-engine casing prototype, prove the precision and effectiveness of the proposed method.