MVFM-3DAD：基于密度代理估计的三维异常检测多视图流匹配方法
MVFM-3DAD: Multi-view Flow Matching for 3D Anomaly Detection via Density Proxy Estimation
AI总结：
该研究针对现有三维异常检测方法的局限性，提出MVFM-3DAD框架，将3DAD转化为密度代理估计，在Real3D-AD等数据集上性能优于竞争方法。
AI中文摘要：
在三维异常检测（3DAD）领域，现有多数方法依赖记忆库检索或重构。然而，基于记忆的方法受限于存储的正常特征覆盖范围，而基于重构的方法可能学习到身份捷径，也能很好地重构异常输入。这些局限性促使我们采用面向密度的方法，即评估测试样本是否符合已学习的正常分布。为此，我们提出MVFM-3DAD，这是一种基于流的框架，将3DAD重新表述为对正常数据分布的密度代理估计。MVFM-3DAD引入了双向几何投影器（BGP），其前向过程将不规则点云转换为结构化多视图表示；流引导的密度代理估计器（FDPE）为每个视图特征估计参考密度，之后BGP的反向过程将这些多视图密度估计映射到对应的三维点。基于此，可通过终端正态性识别异常特征。与传统基于流的似然估计不同，我们的方法既不需要输入重构，也不需要显式雅可比行列式评估，从而得到简单高效的异常评分机制。大量实验表明，MVFM-3DAD在Real3D-AD和MVTec3D-AD数据集上的性能优于最强的竞争方法，代码可在该https URL获取。
英文摘要：
In 3D anomaly detection (3DAD), most existing methods rely on Memory bank retrieval or reconstruction. However, memory-based methods are constrained by the coverage of stored normal features, while reconstruction-based methods may learn identity shortcuts that also reconstruct anomalous inputs well. These limitations motivate a density-oriented approach that evaluates whether a test sample follows the learned normal distribution. To this end, we propose MVFM-3DAD, a flow-based framework that reframes 3DAD as density proxy estimation over the normal data distribution. MVFM-3DAD introduces a Bidirectional Geometric Projector (BGP), whose forward process converts irregular point clouds into structured multi-view representations. The Flow-guided Density Proxy Estimator (FDPE) estimates a reference density for each view feature, after which the backward process of BGP maps these multi-view density estimates to their corresponding 3D points. Building on it, anomalous features can be identified by their terminal normality. Unlike conventional flow-based likelihood estimation, our formulation requires neither input reconstruction nor explicit Jacobian evaluation, yielding a simple and efficient anomaly-scoring mechanism. Extensive experiments show that MVFM-3DAD outperforms the strongest competing methods on Real3D-AD and MVTec3D-AD. Code is available at https://github.com/lil-wayne-0319/MV3D-AD
