Fig. 1. Principle diagram of 3D measurement based on line structured light

Fig. 2. 3D measurement system

Fig. 3. 3D point cloud data acquisition system

Fig. 4. Principle diagram of track 3D point cloud data acquisition

Fig. 5. Flow chart of fastener fastening state detection

Fig. 6. Height distribution of i-th contour

Fig. 7. Cumulative height function G(k,i) of profile i

Fig. 8. Segmentation results of rail and fastener area (sampling interval of left rail is 1 mm)

Fig. 9. Wheel rail contact diagram

Fig. 10. Schematic of non-wear rectangular area outside rail head (sampling interval of left rail profile is 1 mm)

Fig. 11. Flow chart of online updating threshold database

Fig. 12. Static accuracy verification at laboratory. (a) Measuring device; (b) two standard blocks; (c) standard block laser section image; (d) measured profile of standard block

Fig. 13. Dynamic test from scene. (a) 3D measurement module; (b) field installation; (c) 3D reconstruction of rail; (d) measured profile of rail

Fig. 14. Wear measurement error perpendicular to rail from scene

Fig. 15. Bolt heights on both sides of rail. (a) Bolt height distributions on both sides; (b) height difference of bolts on both sides