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Journal of Graphics ›› 2023, Vol. 44 ›› Issue (3): 560-569.DOI: 10.11996/JG.j.2095-302X.2023030560

• Computer Graphics and Virtual Reality • Previous Articles     Next Articles

A 3D point cloud defense framework combined with adversarial examples detection and reconstruction

ZHAO Yu-kun(), REN Shuang(), ZHANG Xin-yun   

  1. School of Computer and Information Technology, Beijing Jiaotong University, Beijing 100044, China
  • Received:2022-10-27 Accepted:2022-12-11 Online:2023-06-30 Published:2023-06-30
  • Contact: REN Shuang (1981-), associate professor, Ph.D. His main research interests cover machine learning, computer vision, virtual reality technology, etc. E-mail:sren@bjtu.edu.cn
  • About author:

    ZHAO Yu-kun (1999-), master student. Her main research interests cover 3D point cloud adversarial attack and defense. E-mail:yukun0125@bjtu.edu.cn

  • Supported by:
    National Natural Science Foundation of China(62072025)

Abstract:

The development of 3D point cloud deep neural networks has enabled their application in many high-security tasks. However, adversarial examples could easily lead the normally trained deep learning models to make incorrect predictions, making it essential to improve the robustness of input data to deep neural networks. The existing 3D point cloud defense networks are inefficient and fail to recover the surface deformation of the point cloud and point distribution adequately. To address these issues, a 3D point cloud adversarial defense network framework combining adversarial example detection and reconstruction was proposed. The input sample was first detected by an error-based detector before and after reconstruction. If it was an adversarial example, it was then reconstructed by a variational autoencoder-based reformer before being fed into the classification network. The variational autoencoder’s structure enhanced the learning of numerical voids on the hidden space, and the same number of points before and after reconstruction ensured efficient subsequent networks and better recovery of the point cloud shape. For the experiments, a variety of classical classification models were attacked on the ModelNet40 dataset, and the effectiveness of the detector-reformer defense framework against these attacks was tested. The experiments demonstrated that the defense method outperformed all other defense methods in terms of classification accuracy on PointNet and especially performed well in the attack based on the saliency map and the adversarial generation network. The detector-reformer defense network framework could improve the accuracy from 47.65% to 75.02% on the dropping attacks with 200 points lost. The effectiveness of the detector and reformer on the overall classification accuracy was demonstrated by ablation experiments and visual reconstruction results.

Key words: adversarial defense, adversarial attack, detection of adversarial examples, point cloud reconstruction, point cloud classification

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