Fig. 1. Schematic diagram of system structure

Fig. 2. Calculation process of horizontal 10 m-chord irregularity based on point cloud

Fig. 3. Flowchart of multi-sensor fusion point cloud computing method

Fig. 4. Schematic diagram of system installed in dedicated inspection train

Fig. 5. Initial alignment accuracy evaluation. (a) Comparison between measured shaking angles and reference values; (b) variation of three-axis angle error with time

Fig. 6. Comparison of trajectory calculation results. (a) Comparison of results from multiple methods; (b) detection of train trajectories

Fig. 7. Attitude measurement accuracy assessment. (a) Comparison of measurements; (b) error values

Fig. 8. Position measurement accuracy assessment. (a) Comparison of measurement results; (b) error values

Fig. 9. Position measurement accuracy assessment

Fig. 10. 3D point cloud reconstruction results. (a) Switch rail; (b) crossing; (c) rail joint

Fig. 11. Comparison of vertical 10 m chords. (a) Based on method of this paper; (b) based on trajectory recursion method

Fig. 12. Comparison of results of track geometry measurement. (a) Horizontal 10 m chord; (b) vertical 10 m chord; (c) level