Beyond Outliers and on to Micro-clusters: Vision-Guided Anomaly Detection.

Given a heatmap for millions of points, what patterns exist in the distributions of point characteristics, and how can we detect them and separate anomalies in a way similar to human vision? In this paper, we propose a vision-guided algorithm, EagleMine, to recognize and summarize point groups in the feature spaces. EagleMine utilizes a water-level tree to capture group structures according to vision-based intuition at multiple resolutions, and adopts statistical hypothesis tests to determine the optimal groups along the tree. Moreover, EagleMine can identify anomalous micro-clusters (i.e., micro-size groups), which exhibit very similar behavior but deviate away from the majority. Extensive experiments are conducted for large graph scenario, and show that our method can recognize intuitive node groups as human vision does, and achieves the best performance in summarization compared to baselines. In terms of anomaly detection, EagleMine also outperforms state-of-the-art graph-based methods by significantly improving accuracy in synthetic and microblog datasets.