Title: Learning Human Kinematics by Modeling Temporal Correlations between Joints for Video-based Human Pose Estimation

Abstract: Estimating human poses from videos is critical in human-computer interaction. By precisely estimating human poses, the robot can provide an appropriate response to the human. Most existing approaches use the optical flow, RNNs, or CNNs to extract temporal features from videos. Despite the positive results of these attempts, most of them only straightforwardly integrate features along the temporal dimension, ignoring temporal correlations between joints. In contrast to previous methods, we propose a plug-and-play kinematics modeling module (KMM) based on the domain-cross attention mechanism to model the temporal correlation between joints across different frames explicitly. Specifically, the proposed KMM models the temporal correlation between any two joints by calculating their temporal similarity. In this way, KMM can learn the motion cues of each joint. Using the motion cues (temporal domain) and historical positions of joints (spatial domain), KMM can infer the initial positions of joints in the current frame in advance. In addition, we present a kinematics modeling network (KIMNet) based on the KMM for obtaining the final positions of joints by combining pose features and initial positions of joints. By explicitly modeling temporal correlations between joints, KIMNet can infer the occluded joints at present according to all joints at the previous moment. Furthermore, the KMM is achieved through an attention mechanism, which allows it to maintain the high resolution of features. Therefore, it can transfer rich historical pose information to the current frame, which provides effective pose information for locating occluded joints. Our approach achieves state-of-the-art results on two standard video-based pose estimation benchmarks. Moreover, the proposed KIMNet shows some robustness to the occlusion, demonstrating the effectiveness of the proposed method.