重新定义视频异常检测评估标准,从帧级转向事件级。
From Frames to Events: Rethinking Evaluation in Human-Centric Video Anomaly Detection

- 提出事件中心评估框架,关注连续异常事件而非孤立帧。
- 现有模型在事件定位上表现极差,平均F1仅0.11,远低于帧级性能。
- 提供可复现的事件定位方法与评估标准,适合安防系统研发者。
基于姿态的视频异常检测(VAD)因其隐私保护和对环境变化的鲁棒性而受到广泛关注。然而,传统帧级评估将视频视为孤立帧集合,与真实世界中异常以连贯事件形式出现并被响应的本质严重不符。在实际监控系统中,真正重要的是可靠地检测、定位并报告一个具有明确起始与持续时间的异常事件。帧级指标无法捕捉这一区别,导致对需生成可操作警报的部署场景系统性高估模型性能。本文提出向事件中心视角转变。我们首先审计了SHT、CHAD、NWPUC和HuVAD等常用基准的数据集事件结构。随后引入两种时序事件定位策略:基于分层高斯平滑与自适应二值化的评分精修流程,以及直接输出事件级检测的端到端双分支模型。最后,我们首次建立基于时间动作定位指标的事件级评估标准,包括tIoU匹配与多阈值F1评价。结果量化出显著性能差距:尽管所有最先进模型在NWPUC数据集上的帧级AUC-ROC均超过52%,但其事件级定位精度在最小tIoU=0.2时仍低于10%,跨阈值平均事件级F1仅为0.11。
原文摘要 · Abstract (English)
Pose-based Video Anomaly Detection (VAD) has gained significant attention for its privacy-preserving nature and robustness to environmental variations. However, traditional frame-level evaluations treat video as a collection of isolated frames, fundamentally misaligned with how anomalies manifest and are acted upon in the real world. In operational surveillance systems, what matters is not the flagging of individual frames, but the reliable detection, localization, and reporting of a coherent anomalous event, a contiguous temporal episode with an identifiable onset and duration. Frame-level metrics are blind to this distinction, and as a result, they systematically overestimate model performance for any deployment that requires actionable, event-level alerts. In this work, we propose a shift toward an event-centric perspective in VAD. We first audit widely used VAD benchmarks, including SHT[19], CHAD[6], NWPUC[4], and HuVAD[25], to characterize their event structure. We then introduce two strategies for temporal event localization: a score-refinement pipeline with hierarchical Gaussian smoothing and adaptive binarization, and an end-to-end Dual-Branch Model that directly generates event-level detections. Finally, we establish the first event-based evaluation standard for VAD by adapting Temporal Action Localization metrics, including tIoU-based event matching and multi-threshold F1 evaluation. Our results quantify a substantial performance gap: while all SoTA models achieve frame-level AUC-ROC exceeding 52% on the NWPUC[4], their event-level localization precision falls below 10% even at a minimal tIoU=0.2, with an average event-level F1 of only 0.11 across all thresholds. The code base for this work is available at https://github.com/TeCSAR-UNCC/EventCentric-VAD.
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