Fig. 1. Schematic setup of HSL

Fig. 2. HSL main wave and echo waveform (wavelength 720 nm)

Fig. 3. License plate and altered materials and their reflectance. (a) License plate and altered materials;(b) The distribution of reflectance

Fig. 4. Schematic diagram of the altered license plate recognition method based on hyperspectral LiDAR technology

Fig. 5. The flow chart of twice threshold method

Fig. 6. Original and altered license plate. (a) Original license plate1; (b) Original license plate2; (c) Altered license plate1;(d) Altered license plate2

Fig. 7. License plate and altered material separation. (a) License plate part 1; (b) License plate part 2; (c) Altered part1;(d) Altered part 2

Fig. 8. Reconstructed license plate image. (a) Reconstructed image of Fig. 6(c); (b) Reconstructed image of Fig. 6(d)

Fig. 9. Result of license plate recognition. (a) Recognition result of Fig. 6(c); (b) Recognition result of Fig. 6(d)

Fig. 10. Result of license plate recognition. (a) Original license plate; (b) Altered license plate; (c) License plate part; (d) Altered part; (e) Reconstructed image; (f) Recognition result

Fig. 11. Result of license plate recognition. (a) Original license plate; (b) Altered license plate; (c) License plate part; (d) Altered part; (e) Reconstructed image; (f) Recognition result