Towards Scalable 3D Anomaly Detection and Localization: A Benchmark via 3D Anomaly Synthesis and A Self-Supervised Learning Network
Authors: Wenqiao Li, Xiaohao Xu, Yao Gu, Bozhong Zheng, Shenghua Gao, Yingna Wu

Recently 3D anomaly detection a crucial problem involving fine-grained geometry discrimination is getting more attention. However the lack of abundant real 3D anomaly data limits the scalability of current models. To enable scalable anomaly data collection we propose a 3D anomaly synthesis pipeline to adapt existing large-scale 3D models for 3D anomaly detection. Specifically we construct a synthetic dataset i.e. Anomaly-ShapeNet based on ShapeNet. Anomaly-ShapeNet consists of 1600 point cloud samples under 40 categories which provides a rich and varied collection of data enabling efficient training and enhancing adaptability to industrial scenarios. Meanwhile to enable scalable representation learning for 3D anomaly localization we propose a self-supervised method i.e. Iterative Mask Reconstruction Network (IMRNet). During training we propose a geometry-aware sample module to preserve potentially anomalous local regions during point cloud down-sampling. Then we randomly mask out point patches and sent the visible patches to a transformer for reconstruction-based self-supervision. During testing the point cloud repeatedly goes through the Mask Reconstruction Network with each iteration's output becoming the next input. By merging and contrasting the final reconstructed point cloud with the initial input our method successfully locates anomalies. Experiments show that IMRNet outperforms previous state-of-the-art methods achieving 66.1% in I-AUC on our Anomaly-ShapeNet dataset and 72.5% in I-AUC on Real3D-AD dataset. Our benchmark will be released at https://github.com/Chopper233/Anomaly-ShapeNet.