Chinese Journal of Quantum Electronics ›› 2023, Vol. 40 ›› Issue (5): 770-779.doi: 10.3969/j.issn.1007-5461.2023.05.016

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A recognition method for altered license plate based on hyperspectral lidar technology

SHAO Hui 1,2*, MA Wanli 1, CAO Zheng 1, LI Wei 3, YANG Lijuan 1, XIAO Xiao 1,4, CHEN Jie 1,4   

  1. ( 1 School of Electronic and Information Engineering, Anhui Jianzhu University, Hefei 230601, China; 2 Jiangsu Province Key Laboratory of Image Processing and Image Communication, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; 3 Institute of Unmanned System, Beihang University, Beijing 100191, China; 4 Anhui International Joint Research Center for Ancient Architecture Intellisencing and Multi-Dimensional Modeling, Hefei 230601, China )
  • Received:2021-12-01 Revised:2022-02-12 Published:2023-09-28 Online:2023-09-28

Abstract: Using the spatial-spectral information of the altered license plates collected by hyperspectral lidar system, a twice-threshold method based on spectral feature is designed to recognize the altered license plates according to their retroreflection characteristics. Firstly, the characteristic wavelength of the spectra is selected, then the plate part and the altered material part are separated using the first threshold method according to the reflectance at the wavelength. Secondly, calculate the gradient value of the spectral reflectance curve at each point of the license plate part in the characteristic band, and the second threshold method is used to distinguish the alteration types, such as background to character alteration and character to background alteration. Finally, the correct license plate characters are reconstructed based on the type of the alteration, and the correct license plate image is reconstructed with the fusion of twodimensional data and the corrected license plate characters, which is sent to the license plate recognition system. Experimental results show that this method can recognize altered license plates correctly regardless of different altered materials or different altered types.

Key words: remote sensing, hyperspectral lidar, reflectance, altered license plate

CLC Number: