# Research on a Dynamic Calibration Method for Photogrammetry Based on Rotary Motion
## 1 Introduction  
Photogrammetry is used to calculate the three-dimensional coordinates of space points through the principle of space intersection. With the help of high-precision cameras and fast image processors, photogrammetry can realize real-time measurement and monitoring of multiple points to calculate the attitude and position of a measured object and its shape change, as well as to realize real-time measurement and monitoring of multiple points. Dynamic photogrammetry [1; 2; 3] often adopts a double- or multiple-camera photogrammetry system [4] or a high-speed dynamic photogrammetry system to realize real-time calculation of dynamic geometric parameters. Among existing systems, the commonly used double- or multiple-camera photogrammetry system can usually reach a shooting frame rate of 1000 fps, perform online measurements of spatial three-dimensional coordinates of target points, and measure moving targets. In addition to providing temporal records of an object's space motion, such as deformation, trajectory, velocity, and acceleration curves, dynamic photogrammetry can also identify and image discrete target points. Therefore, dynamic photogrammetry has a wide range of applications in the fields of large component assembly in the aviation industry [5], crash testing in the automotive industry [6], dynamic deformation measurement during metal plate welding [7], calibration and evaluation of robot motion [8], measurement of real-scale heliostats [9], and human motion analysis [10]. For example, current civil aviation aircraft manufacturing adopts an international division of labor and cooperation mechanism. The major parts of an airframe are first produced and assembled by a manufacturer and then shipped to a final assembly plant. The assembly process of large parts involves real-time attitude adjustment and monitoring to realize thecomplete assembly of parts. Through an accurate measurement and trimming of large-sized parts [11], it can avoid excessive clearance in the assembly process caused by dimensional deviation during assembly, which affects the overall performance of large equipment. As a typical large-scale measurement scene, the application of photogrammetry can build a spatial measurement coordinate system with minimum equipment investment and space consumption and realize the real-time measurement of spatial attitude and position [12]. As an engineering application technology widely used in large-scale measurement of space, photogrammetry is very important in terms of its measurement accuracy. At present, the calibration of a photogrammetry system mainly focuses on the calibration of static parameters, such as the internal and external parameters of the camera used in the system. [PERSON] et al. proposed an optimized calibration of a machine vision system based on machine learning, which is beneficial for detecting parts with a large volume [13]. [PERSON] et al. proposed an integrated calibration technique based on rigorous modeling for a three-dimensional imaging system composed of a single camera and a wedge prism, which contributes to the recovery of any spatial object with geometric accuracy [14]. Static parameter calibration can ensure the accurate capture and expression of spatial position points, but it cannot guarantee the dynamic performance of a photogrammetry system. When a photogrammetry system is used for dynamic measurement, more attention should be paid to the accuracy of the geometric parameter measurement results in a dynamic environment [15; 16; 17; 18; 19; 20]. For example, when calibrating the dynamic performance of a laser tracker [21; 22; 23], it is necessary to focus on evaluation parameters, such as dynamic speed limit, dynamic indication error, and dynamic indication variation. This paper proposes a dynamic calibration method based on a circular trajectory standard device for the problem of dynamic parameter calibration of photogrammetry systems.