Affinity Contrastive Learning for Skeleton-based Human Activity Understanding

Fuente: arXiv
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Main Authors: Liu, Hongda, Liu, Yunfan, Ren, Min, Sui, Lin, Wang, Yunlong, Sun, Zhenan
Format: Preprint
Published: 2026
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_version_ 1866908849468866560
author Liu, Hongda
Liu, Yunfan
Ren, Min
Sui, Lin
Wang, Yunlong
Sun, Zhenan
author_facet Liu, Hongda
Liu, Yunfan
Ren, Min
Sui, Lin
Wang, Yunlong
Sun, Zhenan
contents In skeleton-based human activity understanding, existing methods often adopt the contrastive learning paradigm to construct a discriminative feature space. However, many of these approaches fail to exploit the structural inter-class similarities and overlook the impact of anomalous positive samples. In this study, we introduce ACLNet, an Affinity Contrastive Learning Network that explores the intricate clustering relationships among human activity classes to improve feature discrimination. Specifically, we propose an affinity metric to refine similarity measurements, thereby forming activity superclasses that provide more informative contrastive signals. A dynamic temperature schedule is also introduced to adaptively adjust the penalty strength for various superclasses. In addition, we employ a margin-based contrastive strategy to improve the separation of hard positive and negative samples within classes. Extensive experiments on NTU RGB+D 60, NTU RGB+D 120, Kinetics-Skeleton, PKU-MMD, FineGYM, and CASIA-B demonstrate the superiority of our method in skeleton-based action recognition, gait recognition, and person re-identification. The source code is available at https://github.com/firework8/ACLNet.
format Preprint
id arxiv_https___arxiv_org_abs_2601_16694
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Affinity Contrastive Learning for Skeleton-based Human Activity Understanding
Liu, Hongda
Liu, Yunfan
Ren, Min
Sui, Lin
Wang, Yunlong
Sun, Zhenan
Computer Vision and Pattern Recognition
In skeleton-based human activity understanding, existing methods often adopt the contrastive learning paradigm to construct a discriminative feature space. However, many of these approaches fail to exploit the structural inter-class similarities and overlook the impact of anomalous positive samples. In this study, we introduce ACLNet, an Affinity Contrastive Learning Network that explores the intricate clustering relationships among human activity classes to improve feature discrimination. Specifically, we propose an affinity metric to refine similarity measurements, thereby forming activity superclasses that provide more informative contrastive signals. A dynamic temperature schedule is also introduced to adaptively adjust the penalty strength for various superclasses. In addition, we employ a margin-based contrastive strategy to improve the separation of hard positive and negative samples within classes. Extensive experiments on NTU RGB+D 60, NTU RGB+D 120, Kinetics-Skeleton, PKU-MMD, FineGYM, and CASIA-B demonstrate the superiority of our method in skeleton-based action recognition, gait recognition, and person re-identification. The source code is available at https://github.com/firework8/ACLNet.
title Affinity Contrastive Learning for Skeleton-based Human Activity Understanding
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2601.16694