Unsupervised clustering is a kind of popular solution for unsupervised person reidentification (re-ID). However, due to the influence of cross-view differences, the results of clustering labels are not accurate. To solve this problem, an unsupervised re ID method based on cross-view distributed alignment (CV-DA) to reduce the influence of unsupervised cross-view is proposed. Specifically, based on a popular unsupervised clustering method, density clustering DBSCAN is used to obtain pseudo labels. By calculating the similarity scores of images in the target domain and the source domain, the similarity distribution of different camera views is obtained and is aligned with the distribution with the consistency constraint of pseudo labels. The cross-view distribution alignment constraint is used to guide the clustering process to obtain a more reliable pseudo label. The comprehensive comparative experiments are done in two public datasets, i.e. Market-1501 and DukeMTMC-reID. The comparative results show that the proposed method outperforms several state-of-the-art approaches with mAP reaching 52.6% and rank1 71.1%. In order to prove the effectiveness of the proposed CV-DA, the proposed constraint is added into two advanced re-ID methods. The experimental results demonstrate that the mAP and rank increase by ∽0.5-2% after using the cross-view distribution alignment constraint comparing with that of the associated original methods without using CV-DA.
INTRODUCTIONPerson re-identification (re-ID) [1] aims to locate the target person in surveillance videos with a given probe image. With the rapid development of deep learning to techniques, most person re-ID methods focus on supervised algorithm and have achieved high accuracy on public datasets. However, they need to have many pairs of label data between each pair of camera views, which limits the scalability of large-scale applications. In large-scale programs, manually marking pairs of re-ID data is time-consuming and laborious, only unlabelled data is available. In order to solve the scalability problem of re-ID large-scale program, unsupervised re-ID has been widely concerned. Unsupervised learning is achieved by migrating the source domain to the target domain. However, due to the data deviation between the source dataset and the target dataset, the target domain's performance may decrease significantly [2,3].This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.