Motion Semantics Guided Normalizing Flow for Privacy-Preserving Video Anomaly Detection

Fuente: arXiv
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Autori principali: Liu, Yang, Chen, Boan, Meng, Yuanyuan, Liu, Jing, Guo, Zhengliang, Zhou, Wei, Sun, Peng, Chen, Hong
Natura: Preprint
Pubblicazione: 2026
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author Liu, Yang
Chen, Boan
Meng, Yuanyuan
Liu, Jing
Guo, Zhengliang
Zhou, Wei
Sun, Peng
Chen, Hong
author_facet Liu, Yang
Chen, Boan
Meng, Yuanyuan
Liu, Jing
Guo, Zhengliang
Zhou, Wei
Sun, Peng
Chen, Hong
contents As embodied perception systems increasingly bridge digital and physical realms in interactive multimedia applications, the need for privacy-preserving approaches to understand human activities in physical environments has become paramount. Video anomaly detection is a critical task in such embodied multimedia systems for intelligent surveillance and forensic analysis. Skeleton-based approaches have emerged as a privacy-preserving alternative that processes physical world information through abstract human pose representations while discarding sensitive visual attributes such as identity and facial features. However, existing skeleton-based methods predominantly model continuous motion trajectories in a monolithic manner, failing to capture the hierarchical nature of human activities composed of discrete semantic primitives and fine-grained kinematic details, which leads to reduced discriminability when anomalies manifest at different abstraction levels. In this regard, we propose Motion Semantics Guided Normalizing Flow (MSG-Flow) that decomposes skeleton-based VAD into hierarchical motion semantics modeling. It employs vector quantized variational auto-encoder to discretize continuous motion into interpretable primitives, an autoregressive Transformer to model semantic-level temporal dependencies, and a conditional normalizing flow to capture detail-level pose variations. Extensive experiments on benchmarks (HR-ShanghaiTech & HR-UBnormal) demonstrate that MSG-Flow achieves state-of-the-art performance with 88.1% and 75.8% AUC respectively.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26745
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Motion Semantics Guided Normalizing Flow for Privacy-Preserving Video Anomaly Detection
Liu, Yang
Chen, Boan
Meng, Yuanyuan
Liu, Jing
Guo, Zhengliang
Zhou, Wei
Sun, Peng
Chen, Hong
Computer Vision and Pattern Recognition
As embodied perception systems increasingly bridge digital and physical realms in interactive multimedia applications, the need for privacy-preserving approaches to understand human activities in physical environments has become paramount. Video anomaly detection is a critical task in such embodied multimedia systems for intelligent surveillance and forensic analysis. Skeleton-based approaches have emerged as a privacy-preserving alternative that processes physical world information through abstract human pose representations while discarding sensitive visual attributes such as identity and facial features. However, existing skeleton-based methods predominantly model continuous motion trajectories in a monolithic manner, failing to capture the hierarchical nature of human activities composed of discrete semantic primitives and fine-grained kinematic details, which leads to reduced discriminability when anomalies manifest at different abstraction levels. In this regard, we propose Motion Semantics Guided Normalizing Flow (MSG-Flow) that decomposes skeleton-based VAD into hierarchical motion semantics modeling. It employs vector quantized variational auto-encoder to discretize continuous motion into interpretable primitives, an autoregressive Transformer to model semantic-level temporal dependencies, and a conditional normalizing flow to capture detail-level pose variations. Extensive experiments on benchmarks (HR-ShanghaiTech & HR-UBnormal) demonstrate that MSG-Flow achieves state-of-the-art performance with 88.1% and 75.8% AUC respectively.
title Motion Semantics Guided Normalizing Flow for Privacy-Preserving Video Anomaly Detection
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.26745