DeST: A Decoupled Spatio-Temporal Framework for Action Segmentation
摘要
Effectively modeling discriminative spatio-temporal information is essential for segmenting activities in long action sequences. However, we observe that existing methods are limited in weak spatio-temporal modeling capability due to two forms of coupled modeling: (i) Cascaded interaction couples spatial and temporal modeling, which over-smooths motion modeling over the long sequence, and (ii) Joint-shared temporal modeling adopts shared weights to model each joint, ignoring the distinct motion patterns of different joints. In this paper, we present a Decoupled Spatio-Temporal Framework (DeST) to address the above issues. Firstly, we decouple the cascaded spatio-temporal interaction to avoid stacking multiple spatio-temporal blocks, while achieving sufficient spatio-temporal interaction. Specifically, DeST performs once unified spatial modeling and divides the spatial features into different groups of sub-features, which then adaptively interact with temporal features from different layers. Since the different sub-features contain distinct spatial semantics, the model could learn better interaction patterns at each layer. Meanwhile, inspired by the fact that different joints move at different speeds, we propose joint-decoupled temporal modeling, which employs independent trainable weights to capture distinctive temporal features of each joint. On four large-scale benchmarks of different scenes, DeST significantly outperforms current state-of-the-art methods with less computational complexity. Our code is available at: https://github.com/lyhisme/DeST.