提出一种高效多视图异常检测方法,直接构建跨视图一致邻域。
SCoNE: Spherical Consistent Neighborhoods Ensemble for Effective and Efficient Multi-View Anomaly Detection
- 直接用多视图实例构建一致邻域,无需中间表示
- 稀疏区邻域大、密集区邻域小,提升一致性表现
- 时间复杂度降至O(N),适合大规模数据
多视图异常检测的核心挑战是跨视图一致地表示正常样本的局部邻域。现有方法在各视图中独立表示局部邻域,再通过学习过程捕捉跨视图的一致邻域,存在两大缺陷:其一,难以保证一致邻域的有效捕获,尤其当相同邻域在不同视图中处于密度差异区域时,导致检测精度下降;其二,学习过程计算复杂度高达$/mathcal{O}(N^2)$,难以应用于大规模数据集。为此,本文提出新型方法SCoNE(Spherical Consistent Neighborhoods Ensemble),具有两个关键特性:(a) 以多视图实例直接表示一致邻域,无需中间表示;(b) 邻域具数据依赖性,稀疏区域邻域大,密集区域邻域小。该特性使不同视图的局部邻域自然保持一致,无需学习。整体时间复杂度降为$/mathcal{O}(N)$。实验表明,SCoNE在检测精度上优于现有方法,且在大规模数据上运行速度提升数个数量级。
原文摘要 · Abstract (English)
The core problem in multi-view anomaly detection is to represent local neighborhoods of normal instances consistently across all views. Recent approaches consider a representation of local neighborhood in each view independently, and then capture the consistent neighbors across all views via a learning process. They suffer from two key issues. First, there is no guarantee that they can capture consistent neighbors well, especially when the same neighbors are in regions of varied densities in different views, resulting in inferior detection accuracy. Second, the learning process has a high computational cost of $\mathcal{O}(N^2)$, rendering them inapplicable for large datasets. To address these issues, we propose a novel method termed \textbf{S}pherical \textbf{C}onsistent \textbf{N}eighborhoods \textbf{E}nsemble (SCoNE). It has two unique features: (a) the consistent neighborhoods are represented with multi-view instances directly, requiring no intermediate representations as used in existing approaches; and (b) the neighborhoods have data-dependent properties, which lead to large neighborhoods in sparse regions and small neighborhoods in dense regions. The data-dependent properties enable local neighborhoods in different views to be represented well as consistent neighborhoods, without learning. This leads to $\mathcal{O}(N)$ time complexity. Empirical evaluations show that SCoNE has superior detection accuracy and runs orders-of-magnitude faster in large datasets than existing approaches.
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