Research and verification of space position of precast segmental beam based on photogrammetry

In the process of aligning and assembling prefabricated segmental beams, the measurement method of using total station to obtain spatial pose has the problems of high manual dependence, low measurement efficiency and high construction risk. The existing non-contact measurement methods are analyzed. It is concluded that photogrammetry has the conditions to realize automatic measurement and can reduce certain construction risks. According to the complex situation of bridge construction site and the harsh environment, traditional camera calibration methods are not applicable. Therefore, a self-calibration method is proposed. At the same time, according to the self-calibration algorithm, all photos taken cannot be solved, and there are problems of photo redundancy. The algorithm is further optimized to obtain a focal length calibration method based on global scanning, and the camera shooting is used to test and verify the construction site of prefabricated segmental beam assembly to explore whether the measurement accuracy of the method can meet the construction requirements in the actual construction environment. The results show that the measurement method can be realized in the construction environment of precast segmental beams. And the measurement accuracy meets the assembly requirements of precast segmental beams.