CLIP-Guided Progressive Body-Part Semantic Alignment for Visible-Infrared Person Re-Identification

Abstract

Visible-infrared person re-identification (VI-ReID) aims to retrieve pedestrian images of the same identity across visible and infrared modalities, but remains challenging due to the large modality gap and unstable local correspondence. Existing methods mainly rely on visual cues, which may be insufficient when infrared images lack color and fine-grained texture information. To address this issue, this paper proposes a CLIP-Guided Progressive Body-Part Semantic Alignment Network, termed PBSA-Net. The proposed method introduces CLIP-derived textual semantics as modality-agnostic guidance for both global representation learning and local body-part feature extraction. Specifically, a global semantic branch first learns identity-level textual anchors to regularize global visual features. Then, a body-part semantic branch exploits identity-aware body-part prompt learning, multi-level feature fusion, and text-guided cross-attention to guide fine-grained local representation learning. A progressive three-stage optimization strategy is further adopted to decouple global semantic learning, body-part semantic correspondence learning, and retrieval-oriented feature optimization. Experiments on SYSU-MM01, RegDB, and LLCM demonstrate the effectiveness of PBSA-Net. It achieves 76.5% Rank-1 and 74.2% mAP on SYSU-MM01, 82.5% Rank-1 and 76.0% mAP on RegDB, and 61.8% Rank-1 and 65.8% mAP on LLCM. Ablation studies further show that the proposed body-part semantic alignment and progressive optimization provide complementary improvements.