# Research on a Dynamic Calibration Method for Photogrammetry Based on Rotary Motion
## 4 Experiment and Analysis
### Test Procedure  
The main test steps are as follows (Figure 7):  
1. Connect the test equipment including the circular trajectory generator and the dual-camera real-time photogrammetry system. 2. Camera calibration and control field calibration. Connect two cameras and calibrate them one by one. Turn on the laser indication of the camera. The operator, while holding the camera, stands about 3 m in front of the calibration field and points the camera at the center position of the calibration field at different positions at above and below, as well as left and right, of the calibration field (the camera pointing can be adjusted according to the laser indication) to take the calibration images. The number of images taken should not be less than 30; the position distribution in front of the calibration field should be basically even; and the images should be obtained from nine directions, and each direction is generally rotated four times around the optical axis of the camera, at 90\({}^{\circ}\) each time. After shooting, multiple images are used to solve the parameters in the camera and complete the camera calibration, as shown in Figure 8. Simultaneously, the control field is photographed with a camera to obtain the coordinates of each control point in the control field, as shown in Figure 9. The external parameter and the control field calibration data are then solved. 3. Control field orientation. Install the two cameras on the tripod head, respectively; turn on the laser pointer, adjust the tripod or head; and adjust the pointing laser of the camera to the circular track generator. Use the measurement software to complete the control field orientation and determine the position of the two cameras. 4. Dynamic measurement. Using the continuous measurement and deformation monitoring functions of the measuring system, two coding points on the rotating rod of the circular track are selected as the monitoring objects. The circular trajectory generator's controller controls the rotational speed, so that after the rotation rod rotates at a certain speed, the dual-camera photogrammetry system tracks and measures the two coding points and records the coordinate changes of the two points. \begin{table}
\begin{tabular}{c c} \hline \hline
**Technical Index** & **MPS/M10** \\ \hline Resolution ratio & 8 M \\ Measuring accuracy & 12 \(\mu\)m + 12 ppm\(\cdot\)L \\  & 0.05 mm\#3 m \\ Measurement accuracy of displacement and profile & 0.03 mm\#3 m \\   Field angle & 70.6\({}^{\circ}\) \\   Measuring speed & Real-time processing of 5 frames/SEC; \\   Measuring range & Post-processing of 10 frames per second \\ \hline \hline \end{tabular}
\end{table} 
Table 2: MPS/M10 technical specifications. Figure 7: Experimental procedure. Figure 11: Measurement results of the distance between two targets in a stationary state. Figure 12: Measurement results of the distance between two targets at 0.5 r/s. Figure 13: Measurement results of the distance between two targets at 1 r/s. Figure 16: Measurement results of the distance between two targets at 4 r/s. Figure 14: Measurement results of the distance between two targets at 2 r/s. Figure 15: Measurement results of the distance between two targets at 3 r/s. The above experimental data statistics are as follows (shown in Table 3 and Figure 17):  
The moving speed of a target point can be calculated according to the spatial coordinates of the measured target point at a certain time and the time of image collection. About 400 frames of images are collected at each speed. The calculated results at different speeds are as follows (shown in Table 4):  
1. The amount of angle change represents the angle of rotation of the marker point relative to the previous position, and at the same time, the linear velocity and angular velocity in the table are all converted from this motion angle to time. 2.