Person reidentification (ReID) is a very popular research topic in machine learning and computer vision. According to the occlusions, it can be divided into holistic person ReID and partial person ReID tasks. Occlusions commonly exist in the partial person ReID task but pose or observation perspective changes often occur in the holistic person ReID task; thus, many different algorithms or different network architectures have been designed for each task. However, this approach increases the cost in practice and hinders the development of ReID techniques. To solve this problem, in this work, a unified framework is proposed for holistic/partial person ReID, which can effectively and efficiently address changes in pose or observation perspective and the occlusions in both tasks. In detail, we first employ a fully convolutional network (FCN) to generate feature maps for an arbitrarily sized image and then use spatial pyramid pooling (SPP) to obtain its spatial pyramid feature. Thereafter, to efficiently solve the matching problem between the query image and gallery images, we build a deep spatial pyramid feature collaborative reconstruction model (DCR). In DCR, the reconstruction errors mainly come from similar blocks (uncovered parts), and the influence of the reconstruction errors of dissimilar blocks (covered parts or changed parts) is minimized. In addition, we also use the deep mutual learning approach to jointly learn the features in the training process and promote model training. Experimental results on two partial person ReID datasets and three holistic person ReID datasets demonstrate that the DCR outperforms the state-of-the-art approaches on both tasks and all datasets. Specifically, it outperforms all competitors with a large margin and achieves an improvement of 9.07% and 5.95% over the DSR method (published in CVPR18) on the Partial ReID and Partial-iLIDS datasets with Rank-1, respectively. Similarly, it also achieves an improvement of 5.08% over the VPM method (published in CVPR19) on the DukeMTMC-ReID dataset with Rank-1. Additionally, the running time of our method for each query is more than 7 faster than that of the DSR or DuATM methods.

In real person re-identification (ReID) tasks, pedestrians are often obscured by other pedestrians or objects; moreover, changes in poses or observation perspectives also commonly exist in partial-person ReID. To the best of our knowledge, few works simultaneously focus on these two issues. In this work, we propose a novel texture semantic alignment (TSA) approach with the visibility-aware for partial person ReID task where the occlusion issue and changes in poses are simultaneously explored in an end-to-end unified framework. Specifically, we first employ a texture alignment scheme with the semantic visibility of a person's image to solve the issue of changes in poses that can enhance the alignment and generalization capability of the models. Second, we design a human pose-based partial region alignment scheme to solve the occlusion problem that makes TSA method emphasize the shared body parts. Finally, these two networks jointly learn these aspects. Extensive experimental results demonstrate that our proposed TSA method is very effective and robust for simultaneously handling occlusion and changes in pose, and it can outperform state-of-the-art approaches by a large margin and achieves an improvement of 5% and 6.4% on the rank-1 accuracy over the visibility-aware part model (VPM) method (published in CVPR 2019) on the Partial ReID and Partial-iLIDS datasets, respectively.

Partial person re-identification (ReID) is a hot research problem in computer vision. Accurate partial ReID is very challenging due to the common occlusion problem. To address this problem, in this paper, we propose a novel D eep spatial pyramid feature C ollaborative R econstruction approach (DCR ) for partial person ReID, which can effectively and efficiently tackle the occlusion in arbitrary sizes. Specifically, a fully convolutional network (FCN) is first leveraged to extract feature maps of an arbitrary-size image, and then the spatial pyramid pooling (SPP) is adopted to obtain spatial pyramid features. Thereafter, our DCR method is designed to efficiently solve the matching problem between the partial person and the holistic person in the partial person ReID task where the occlusion problem often occurs. Experiments on two partial person ReID datasets demonstrate the efficiency and efficacy of the proposed method by comparing to several state-of-the-art partial person ReID approaches. Our method outperforms all the competitors with a large margin and can achieve an improvement of 9.07% and 5.95% over the DSR method on the Partial REID and Partial-iLIDS Person ReID datasets in terms of the Rank-1 accuracy, respectively.