Bridging the Pose-Semantic Gap: A Cascade Framework for Text-Based Person Anomaly Search

Zequn Xie, Guijin Luo, Chuxin Wang, Sihang Cai, Tao Jin, Zhou Zhao, Yixuan Tang


Abstract
Text-based person anomaly search retrieves specific behavioral events from surveillance archives using natural-language queries. Although recent pose-aware methods align geometric structures well, they face a fundamental Pose-Semantic Gap: semantically different actions can share similar skeletal geometries. While Multimodal Large Language Models (MLLMs) can reduce this ambiguity, using them for large-scale retrieval is computationally prohibitive. We propose the Structure-Semantic Decoupled Cascade (SSDC) framework, which decouples retrieval into two stages: (1) Structure-Aware Coarse Retrieval, where a lightweight model quickly filters candidates by skeletal similarity; and (2) Detective Squad Interaction, a multi-agent semantic verification module. The squad consists of a Detective for fast binary filtering, an Analyst for evidence extraction, and a Writer for semantic synthesis. Finally, we re-rank candidates by fusing the synthesized captions with structural priors. Experiments on the PAB benchmark show that SSDC achieves state-of-the-art performance by balancing efficiency and semantic reasoning.
Anthology ID:
2026.findings-acl.197
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
4040–4049
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URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.197/
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Cite (ACL):
Zequn Xie, Guijin Luo, Chuxin Wang, Sihang Cai, Tao Jin, Zhou Zhao, and Yixuan Tang. 2026. Bridging the Pose-Semantic Gap: A Cascade Framework for Text-Based Person Anomaly Search. In Findings of the Association for Computational Linguistics: ACL 2026, pages 4040–4049, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Bridging the Pose-Semantic Gap: A Cascade Framework for Text-Based Person Anomaly Search (Xie et al., Findings 2026)
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