Fig. 1. Camera imaging model

Fig. 2. Flowchart of two-step calibration

Fig. 3. Principle of pyramid method

Fig. 4. Flow chart of 3D reconstruction process of the photogrammetry

Fig. 5. Coding mark point

Fig. 6. Experiment environment

Fig. 7. Schematic diagram of internal parameter calibration

Fig. 8. Image acquisition and coding point recognition for internal parameter calibration

Fig. 9. Image acquisition and coding point recognition for internal parameter calibration

Fig. 10. Error distribution of reprojection

Fig. 11. Invar alloy standard ruler

Fig. 12. Images of the ruler in different positions

Fig. 13. Experiment site of the rotor tower

Fig. 14. Total pitch angle of the rotor

Fig. 15. Result of three-dimensional deformation of the rotor

Fig. 16. Result of total pitch angle of the rotor