Universal adjustment model for visual photogrammetry and application in three-dimensional high-accuracy measurement of spatial targets

In order to meet the high-precision measurement requirements of point and line targets for particle accelerators, the visual photogrammetry system for three-dimensional measurement is proposed, and the data processing algorithm is investigated. First, based on the images collected by visual measurement, the pixel observations are converted into universal angle observations. An observation model for points based on angle observations is proposed, and the relation between angle observations and global coordinates is established. Then, a spatial straight line of a four-parameter expression method is proposed, and an offset observation model for the line is established. Finally, based on the principle of indirect adjustment, error equations are established, and an overall adjustment solution is achieved for point targets and line targets. Experimental results show that the coordinate component differences are within 25 μm for point targets when comparing the coordinates measured by this system with those measured by a three-coordinate machine. The differences for line targets are within 10 μm in the transverse direction but large in vertical, possibly due to the influence of the illumination. The universal adjustment method for three-dimensional visual measurement proposed in this paper extends the measurement capability from point targets to line targets, providing a comprehensive solution for both types of targets. This method can also be applied for the data processing of multi-system combination measurements of visual photogrammetry systems and laser trackers, leveraging the strengths of different measurement systems and having broad application prospects.