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A Multi-Stream Graph Convolutional Networks-Hidden Conditional Random Field Model for Skeleton-Based Action Recognition

Recently, Graph Convolutional Network(GCN) methods for skeleton-based action recognition have achieved great success due to their ability to preserve structural information of the skeleton. However, these methods abandon the structural information in the classification stage by employing traditional fully-connected layers and softmax classifier, leading to sub-optimal performance. In this work, a novel Graph Convolutional Networks-Hidden conditional Random Field (GCN-HCRF) model is proposed to solve this problem. The proposed method combines GCN with HCRF to retain the human skeleton structure information even during the classification stage. Our model is trained end-to-end by utilizing the message passing from the belief propagation algorithm on the human structure graph. To further capture spatial and temporal information, we propose a multi-stream framework which takes the relative coordinate of the joints and bone direction as two static feature streams, and the temporal displacements between two consecutive frames as the dynamic feature stream. Experimental results on three challenging benchmarks (NTU RGB+D, N-UCLA, SYSU) show the superior performance of the proposed model over state-of-the-art models.