Papers › Actionlet-Dependent Contrastive Learning for Unsupervised Skeleton-Based Action Recognition

Actionlet-Dependent Contrastive Learning for Unsupervised Skeleton-Based Action Recognition

20 Mar 2023CVPR 2023 1arXiv:2303.10904archive 2025-07-28

Lilang Lin, Jiahang Zhang, Jiaying Liu

The self-supervised pretraining paradigm has achieved great success in skeleton-based action recognition. However, these methods treat the motion and static parts equally, and lack an adaptive design for different parts, which has a negative impact on the accuracy of action recognition. To realize the adaptive action modeling of both parts, we propose an Actionlet-Dependent Contrastive Learning method (ActCLR). The actionlet, defined as the discriminative subset of the human skeleton, effectively decomposes motion regions for better action modeling. In detail, by contrasting with the static anchor without motion, we extract the motion region of the skeleton data, which serves as the actionlet, in an unsupervised manner. Then, centering on actionlet, a motion-adaptive data transformation method is built. Different data transformations are applied to actionlet and non-actionlet regions to introduce more diversity while maintaining their own characteristics. Meanwhile, we propose a semantic-aware feature pooling method to build feature representations among motion and static regions in a distinguished manner. Extensive experiments on NTU RGB+D and PKUMMD show that the proposed method achieves remarkable action recognition performance. More visualization and quantitative experiments demonstrate the effectiveness of our method. Our project website is available at https://langlandslin.github.io/projects/ActCLR/

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Tasks

Action RecognitionContrastive LearningSelf-supervised Skeleton-based Action RecognitionSkeleton Based Action RecognitionUnsupervised Skeleton Based Action Recognition

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Skeleton Based Action Recognition NTU RGB+D 3s-ActCLR Accuracy (CS) 84.3 #98 of 135 Archive leaderboard report
Skeleton Based Action Recognition NTU RGB+D 3s-ActCLR Accuracy (CV) 88.8 #98 of 135 Archive leaderboard report

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Methods

Contrastive Learning

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