Language-guided temporal primitive modeling for skeleton-based action recognition

Human actions describe the complex body dynamics, which are defined by an ordered set of sub-action primitives. Existing methods in skeleton-based action recognition primarily focus on designing various networks to learn the entire action representation, in alignment with the action label. However, training the heterogeneous action as a whole increases the burden on the network and is not conducive to learning the temporal structure of the action. In this paper, the traditional action label is extended into the ordered primitive language description by employing a large language model, which not only unveils the temporal structure of the action but also enriches its connotation. Based on this, we propose a language-guided skeleton representation learning network (LGS-Net) that leverages the language description to guide the skeleton feature learning from the ordered primitive and global action levels. Especially, the primitive guidance aligns the features of skeleton clips with those of the ordered primitive descriptions while preserving temporal order, which promotes the network to model the temporal primitive and capture the internal structure within the action from skeletons. To enhance the cross-modal alignment performance, we develop an innovative temporal alignment loss supplemented with diversity and sparsity regularization terms to generate the discriminative multi-modal representation. Evaluated on three benchmark datasets, NTU-60, NTU-120 and N-UCLA, the proposed LGS-Net achieves comparable results to state-of-the-art methods, which proves the effectiveness of the language-guided learning mechanism.