Large object vision measurement system based on a fixed connection between a camera and a total station telescope.

Vision measuring, involving the measurement of the three-dimensional shape and color of large objects using stereo vision-based methods, is a challenging task. In this study, a freely adjustable vision measurement system for large objects is developed by connecting a camera to a total station telescope via a fixed mount. In this system, a camera is focused on the target object to be measured in far-range scenarios. A high-precision calibration method is proposed based on non-parametric camera models. In addition, a point cloud-based three-dimensional reconstruction method is developed by integrating with the non-parametric camera models. The experimental results showed that the proposed system has high precision and robustness. When measuring objects from a distance of 8 m in an indoor scenario, the error in the maximum spatial distance measurement between two corner points on the calibration board is less than 0.24 mm. The maximum relative measurement error is less than 0.09%. When measuring an object 20 m away in an outdoor scenario, the average error in the spatial distance measurement between two arbitrary points in an 11 m×4 m testing region is 5.6 mm. The average relative error in the distance measurement is 0.12%.