An Improvements of Deep Learner Based Human Activity Recognition with the Aid of Graph Convolution Features

Many researchers are now focusing on Human Action Recognition (HAR), which is based on various deep-learning features related to body joints and their trajectories from videos. Among many schemes, Joints and Trajectory-pooled 3D-Deep Geometric Positional Attention-based Hierarchical Bidirectional Recurrent convolutional Descriptors (JTDGPAHBRD) can provide a video descriptor by learning geometric features and trajectories of the body joints. But the spatial-temporal dynamics of the different geometric features of the skeleton structure were not explored deeper. To solve this problem, this article develops the Graph Convolutional Network (GCN) in addition to the JTDGPAHBRD to create a video descriptor for HAR. The GCN can obtain complementary information, such as higher-level spatial-temporal features, between consecutive frames for enhancing end-to-end learning. In addition, to improve feature representation ability, a search space with several adaptive graph components is created. Then, a sampling and computation-effective evolution scheme are applied to explore this space. Moreover, the resultant GCN provides the temporal dynamics of the skeleton pattern, which are fused with the geometric features of the skeleton body joints and trajectory coordinates from the JTDGPAHBRD to create a more effective video descriptor for HAR. Finally, extensive experiments show that the JTDGPAHBRD-GCN model outperforms the existing HAR models on the Penn Action Dataset (PAD)

Hierarchically Clustered Representation Learning

The joint optimization of representation learning and clustering in the embedding space has experienced a breakthrough in recent years. In spite of the advance, clustering with representation learning has been limited to flat-level categories, which often involves cohesive clustering with a focus on instance relations. To overcome the limitations of flat clustering, we introduce hierarchically-clustered representation learning (HCRL), which simultaneously optimizes representation learning and hierarchical clustering in the embedding space. Compared with a few prior works, HCRL firstly attempts to consider a generation of deep embeddings from every component of the hierarchy, not just leaf components. In addition to obtaining hierarchically clustered embeddings, we can reconstruct data by the various abstraction levels, infer the intrinsic hierarchical structure, and learn the level-proportion features. We conducted evaluations with image and text domains, and our quantitative analyses showed competent likelihoods and the best accuracies compared with the baselines.Comment: 10 pages, 7 figures, Under review as a conference pape