Three-dimensional shape measurement method and system calibration for an annular inner-wall.

In the field of industrial measurement, capturing a three-dimensional (3D) profile of an annular inner-wall has been a significant challenge. Current methods typically require multiple scans using a 3D scanner or circular structured light technique, which are inefficient and inconvenient to use. To address this issue, an off-axis measurement method and corresponding system has been proposed in this paper based on circular fringe projection. It can be used to reconstruct the 360° profile of an annular inner-wall in a single scan without any movement. Additionally, a full-field calibration method using ray-tracing for this system has also been presented. Compared to the traditional methods, this method features a simple calibration structure, convenient operation and no need for strict coaxial alignment, which enhances the flexibility of the proposed measurement system and contributes to its high efficiency and the integrity of its output data. Simulation and experimental results confirm the effectiveness and practicality of this measuring approach and system calibration method, providing an alternative solution for automated 3D profile measurement of annular inner-wall.