Fig. 1. Principle diagram of line-structured light imaging of rail profile based on traditional unpolarized camera

Fig. 2. Local overexposure of rail laser section image. (a) Areas prone to overexposure; (b) image acquisition device; (c) local overexposure image

Fig. 3. Center of light strip in the overexposed area of rail laser section image

Fig. 4. Schematic diagram of rail profile detection based on polarization imaging

Fig. 5. Polarization filter and pixel distribution of polarization camera

Fig. 6. Polarization component images of rail laser section. (a) 0° directional polarization component image; (b) 135° directional polarization component image; (c) 45° directional polarization component image; (d) 90° directional polarization component image

Fig. 7. Width of light strip in each column of rectangular areas in Fig. 2 and Fig. 6

Fig. 8. Flowchart of image fusion algorithm

Fig. 9. Experimental setup for polarization characteristics of rail laser section image

Fig. 10. 0° and 90° directional polarization component images

Fig. 11. Polarization angle distribution in rectangular region

Fig. 12. Image fusion weights in rectangular areas in Fig. 2 and Fig. 6

Fig. 13. Fusion image F

Fig. 14. Light strip center of fusion image

Fig. 15. Measurement errors of rail profile by our method and traditional method