Abstract
Temporal action detection, aiming to determine the fragment and category of a human action simultaneously from continuous data stream, is still a challenge issue in the field of human–robot interaction, somatosensory game and security monitoring. In this paper, we present a novel one-stage skeleton-based TAD method, Action-CenterNet(ACNet) with a simple anchor-free and fully convolutional encoder-decoder pipeline. Our approach encodes skeleton position and motion data sequence from multiple persons into multi-channel skeleton images which are subsequently preprocessed by view invariant transform and translation-scale invariant. ACNet models each action fragment as a center point along the time dimension and generates a keypoint heatmap to locate and classify action fragments. To ensure the accurate temporal coordinates, the discretization error caused by the output stride of network is also learned. Compared with two-stage methods, ACNet is end-to-end differential and flexible. ACNet is also an anchor-free method avoiding the drawbacks of anchor boxes used in anchor-based TAD methods. Experimental results on PKU-MMD dataset, NTU RGB-D dataset and HITvs dataset reveal the excellent performance of our approach.
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Acknowledgements
This work was supported in part by the National Natural Science Foundation of China (62176072), National Key Research and Development Program of China (No.2019YFB1310004) and Self-Planned Task NO.SKLRS202111B of State Key Laboratory of Robotics and System (HIT).
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Yang, J., Wang, K. & Li, R. Actions as points: a simple and efficient detector for skeleton-based temporal action detection. Machine Vision and Applications 34, 35 (2023). https://doi.org/10.1007/s00138-023-01377-3
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DOI: https://doi.org/10.1007/s00138-023-01377-3