Fig. 1. Ore transportation image on site

Fig. 2. Spectral intensity of solar radiation

Fig. 3. Schematic diagram of infrared structured light ore image acquisition system

Fig. 4. Ore images of visible and infrared structured light under different illumination conditions. (a) Green line laser (no direct sunlight); (b) Infrared laser (no direct sunlight); (c) Green line laser (strong light); (d) Infrared laser (strong light)

Fig. 5. Ideal gray distribution of line structured light cross section. (a) Ideal Gaussian distribution; (b) Flattened Gaussian distribution

Fig. 6. Gray distribution of visible and infrared structure cross section under different light environment. (a) Green line laser (no direct sunlight); (b) Infrared laser (no direct sunlight); (c) Green line laser (strong light); (d) Infrared laser (strong light)

Fig. 7. Schematic diagram of sliding differential template. (a) Backward; (b) Forward

Fig. 8. Forward cumulative difference

Fig. 9. Measurement of gauge block. (a) Schematic diagram of gauge block projection line; (b) Schematic diagram of height formation

Fig. 10. Extraction result of different method. (a) Gauss method; (b) Steger method; (c) Proposed method

Fig. 11. Results of local center line deviation. (a) Gauss method; (b) Steger method; (c) Proposed method

Fig. 12. Endpoint centerline bifurcation by Steger method

Fig. 13. Enlarged result in the yellow box in Fig.12. (a) Box A; (b) Box B; (c) Box C; (d) Box D

Fig. 14. 3D point cloud display and screening results of ore