最近的研究表明，接受合成数据集培训的模型能够实现比在公共现实世界数据集中培训的更高概括的人重新识别（GPREID）性能。另一方面，由于现实世界中的人REID数据集的局限性，使用大规模合成数据集作为测试集对基准人REID算法也很重要且有趣。然而，这提出了一个关键的问题：合成数据集可靠地测试可概括的人重新识别吗？在文献中，没有证据表明这一点。为了解决这个问题，我们设计了一种称为成对排名分析（PRA）的方法，以定量测量排名相似性并执行相同分布的统计检验。具体而言，我们采用Kendall等级相关系数来评估不同数据集上算法排名之间的成对相似性值。然后，进行非参数的两样本Kolmogorov-smirnov（KS）测试，以判断合成数据集和现实世界数据集之间的算法排名是否在相同的分布中排名在合成数据集和现实世界数据集之间的相关性。我们进行了全面的实验，具有十种代表性算法，三个流行的真实人物REID数据集和三个最近发布的大规模合成数据集。通过设计的成对排名分析和全面评估，我们得出结论，最近可以可靠地使用一个大规模合成数据集克隆人来基准GPREID，从统计学上讲与现实世界数据集相同。因此，本研究保证了源训练集和目标测试集的合成数据集使用，而实际上没有现实世界监视数据的隐私问题。此外，本文中的研究还可能激发合成数据集的未来设计。

变压器最近在计算机视觉中获得了越来越高的关注。然而，现有研究大多用于特征表示学习的变压器，例如，用于图像分类和密集预测，变压器的普遍性是未知的。在这项工作中，我们进一步调查了对图像匹配和度量学习的应用变压器的可能性。我们发现视觉变压器（VIT）和带解码器的Vanilla变压器由于它们缺乏图像与图像而受到图像匹配。因此，我们进一步设计了两种天真的解决方案，即vit的查询画廊串联，并在香草变压器中的Query-Gallery横向关注。后者提高了性能，但它仍然有限。这意味着变压器中的注意机制主要用于全局特征聚合，这不是自然适用于图像匹配。因此，我们提出了一种新的简化解码器，它可以使用SoftMax加权丢弃全部注意力实现，只能保持查询关键相似性计算。此外，还应用全局最大池和多层的Perceptron（MLP）头来解码匹配结果。这样，简化的解码器在计算上更有效，而同时对图像匹配更有效。所谓的方法称为传输函数，在概括的人重新识别中实现最先进的性能，在几个流行的数据集中分别在Rank-1中的性能增长高达6.1％和5.7％。代码可在https://github.com/shengcailiao/qaconv获得。

最近的研究表明，明确的深度特征匹配以及大规模和多样化的训练数据都可以显着提高人员重新识别的泛化。然而，在大规模数据上学习深度匹配者的效率尚未得到充分研究。虽然使用分类参数或课程内存是一种流行的方式，但它会引发大的内存和计算成本。相比之下，迷你批量内的成对深度度量学习将是一个更好的选择。然而，最受欢迎的随机采样方法，众所周知的PK采样器，对深度度量学习不是信息性和有效的。虽然在线硬示例挖掘在一定程度上提高了学习效率，但随机采样后迷你批次仍然有限。这激发了我们在数据采样阶段之前探讨了先前使用硬示例挖掘。为此，在本文中，我们提出了一种有效的跨批量采样方法，称为图形采样（GS），用于大规模深度度量学习。基本思想是为每个时代开始的所有类构建最近的邻居关系图。然后，每个迷你批处理由随机选择的类和其最近的邻类组成，以便为学习提供信息和具有挑战性的例子。与适应的竞争性基线一起，我们在更广泛的人中改善了先前的最先进状态，在MAP中最明显重新鉴定，高达24％和13.8％。此外，所提出的方法还优于竞争性基线在地图中排名-1和5.3％的竞争性基线。同时，培训时间明显减少了多达五次，例如五次。在具有8,000个身份的大型数据集中培训12.2小时至2.3小时。代码可在https://github.com/shengcailiao/qaconv获得。

Recently, Person Re-Identification (Re-ID) has received a lot of attention. Large datasets containing labeled images of various individuals have been released, allowing researchers to develop and test many successful approaches. However, when such Re-ID models are deployed in new cities or environments, the task of searching for people within a network of security cameras is likely to face an important domain shift, thus resulting in decreased performance. Indeed, while most public datasets were collected in a limited geographic area, images from a new city present different features (e.g., people's ethnicity and clothing style, weather, architecture, etc.). In addition, the whole frames of the video streams must be converted into cropped images of people using pedestrian detection models, which behave differently from the human annotators who created the dataset used for training. To better understand the extent of this issue, this paper introduces a complete methodology to evaluate Re-ID approaches and training datasets with respect to their suitability for unsupervised deployment for live operations. This method is used to benchmark four Re-ID approaches on three datasets, providing insight and guidelines that can help to design better Re-ID pipelines in the future.

近年来，随着对公共安全的需求越来越多，智能监测网络的快速发展，人员重新识别（RE-ID）已成为计算机视野领域的热门研究主题之一。人员RE-ID的主要研究目标是从不同的摄像机中检索具有相同身份的人。但是，传统的人重新ID方法需要手动标记人的目标，这消耗了大量的劳动力成本。随着深度神经网络的广泛应用，出现了许多基于深入的基于学习的人物的方法。因此，本文促进研究人员了解最新的研究成果和该领域的未来趋势。首先，我们总结了对几个最近公布的人的研究重新ID调查，并补充了系统地分类基于深度学习的人的重新ID方法的最新研究方法。其次，我们提出了一种多维分类，根据度量标准和表示学习，将基于深度学习的人的重新ID方法分为四类，包括深度度量学习，本地特征学习，生成的对抗学习和序列特征学习的方法。此外，我们根据其方法和动机来细分以上四类，讨论部分子类别的优缺点。最后，我们讨论了一些挑战和可能的研究方向的人重新ID。

Person re-identification (Re-ID) aims at retrieving a person of interest across multiple non-overlapping cameras. With the advancement of deep neural networks and increasing demand of intelligent video surveillance, it has gained significantly increased interest in the computer vision community. By dissecting the involved components in developing a person Re-ID system, we categorize it into the closed-world and open-world settings. The widely studied closed-world setting is usually applied under various research-oriented assumptions, and has achieved inspiring success using deep learning techniques on a number of datasets. We first conduct a comprehensive overview with in-depth analysis for closed-world person Re-ID from three different perspectives, including deep feature representation learning, deep metric learning and ranking optimization. With the performance saturation under closed-world setting, the research focus for person Re-ID has recently shifted to the open-world setting, facing more challenging issues. This setting is closer to practical applications under specific scenarios. We summarize the open-world Re-ID in terms of five different aspects. By analyzing the advantages of existing methods, we design a powerful AGW baseline, achieving state-of-the-art or at least comparable performance on twelve datasets for FOUR different Re-ID tasks. Meanwhile, we introduce a new evaluation metric (mINP) for person Re-ID, indicating the cost for finding all the correct matches, which provides an additional criteria to evaluate the Re-ID system for real applications. Finally, some important yet under-investigated open issues are discussed.

人重新识别（RE-ID）在公共安全和视频监控等应用中起着重要作用。最近，从合成数据引擎的普及中获益的合成数据学习，从公众眼中引起了极大的关注。但是，现有数据集数量，多样性和变性有限，并且不能有效地用于重新ID问题。为了解决这一挑战，我们手动构造一个名为FineGPR的大型人数据集，具有细粒度的属性注释。此外，旨在充分利用FineGPR的潜力，并推广从数百万综合数据的高效培训，我们提出了一个名为AOST的属性分析流水线，它动态地学习了真实域中的属性分布，然后消除了合成和现实世界之间的差距因此，自由地部署到新场景。在基准上进行的实验表明，FineGPR具有AOST胜过（或与）现有的实际和合成数据集，这表明其对重新ID任务的可行性，并证明了众所周知的较少的原则。我们的Synthetic FineGPR数据集可公开可用于\ URL {https://github.com/jeremyxsc/finegpr}。

在视频监视和时尚检索中，识别软性识别人行人属性至关重要。最近的作品在单个数据集上显示了有希望的结果。然而，这些方法在不同属性分布，观点，不同的照明和低分辨率下的概括能力很少因当前数据集中的强偏差和变化属性而很少被理解。为了缩小这一差距并支持系统的调查，我们介绍了UPAR，即统一的人属性识别数据集。它基于四个知名人士属性识别数据集：PA100K，PETA，RAPV2和Market1501。我们通过提供3300万个附加注释来统一这些数据集，以在整个数据集中统一40个属性类别的40个重要二进制属性。因此，我们首次对可概括的行人属性识别以及基于属性的人检索进行研究。由于图像分布，行人姿势，规模和遮挡的巨大差异，现有方法在准确性和效率方面都受到了极大的挑战。此外，我们基于对正则化方法的彻底分析，为基于PAR和属性的人检索开发了强大的基线。我们的模型在PA100K，PETA，RAPV2，Market1501-Atributes和UPAR上的跨域和专业设置中实现了最先进的性能。我们相信UPAR和我们的强大基线将为人工智能界做出贡献，并促进有关大规模，可推广属性识别系统的研究。

域概括人员重新识别旨在将培训的模型应用于未经看明域。先前作品将所有培训域中的数据组合以捕获域不变的功能，或者采用专家的混合来调查特定域的信息。在这项工作中，我们争辩说，域特定和域不变的功能对于提高重新ID模型的泛化能力至关重要。为此，我们设计了一种新颖的框架，我们命名为两流自适应学习（tal），同时模拟这两种信息。具体地，提出了一种特定于域的流以捕获具有批量归一化（BN）参数的训练域统计，而自适应匹配层被设计为动态聚合域级信息。同时，我们在域不变流中设计一个自适应BN层，以近似各种看不见域的统计信息。这两个流自适应地和协作地工作，以学习更广泛的重新ID功能。我们的框架可以应用于单源和多源域泛化任务，实验结果表明我们的框架显着优于最先进的方法。

Person re-identification plays a significant role in realistic scenarios due to its various applications in public security and video surveillance. Recently, leveraging the supervised or semi-unsupervised learning paradigms, which benefits from the large-scale datasets and strong computing performance, has achieved a competitive performance on a specific target domain. However, when Re-ID models are directly deployed in a new domain without target samples, they always suffer from considerable performance degradation and poor domain generalization. To address this challenge, we propose a Deep Multimodal Fusion network to elaborate rich semantic knowledge for assisting in representation learning during the pre-training. Importantly, a multimodal fusion strategy is introduced to translate the features of different modalities into the common space, which can significantly boost generalization capability of Re-ID model. As for the fine-tuning stage, a realistic dataset is adopted to fine-tune the pre-trained model for better distribution alignment with real-world data. Comprehensive experiments on benchmarks demonstrate that our method can significantly outperform previous domain generalization or meta-learning methods with a clear margin. Our source code will also be publicly available at https://github.com/JeremyXSC/DMF.

具有大量空间和时间跨境的情景中的人重新识别（RE-ID）尚未完全探索。这部分原因是，现有的基准数据集主要由有限的空间和时间范围收集，例如，使用在校园特定区域的相机录制的视频中使用的视频。这种有限的空间和时间范围使得难以模拟真实情景中的人的困难。在这项工作中，我们贡献了一个新的大型时空上次最后一个数据集，包括10,862个图像，具有超过228k的图像。与现有数据集相比，最后一个具有挑战性和高度多样性的重新ID设置，以及显着更大的空间和时间范围。例如，每个人都可以出现在不同的城市或国家，以及在白天到夜间的各个时隙，以及春季到冬季的不同季节。为了我们的最佳知识，最后是一个新的Perse Re-ID数据集，具有最大的时空范围。基于最后，我们通过对14个RE-ID算法进行全面的绩效评估来验证其挑战。我们进一步提出了一种易于实施的基线，适用于如此挑战的重新ID设置。我们还验证了初步训练的模型可以在具有短期和更改方案的现有数据集中概括。我们期待持续激发未来的工程，以更现实和挑战的重新识别任务。有关DataSet的更多信息，请访问https://github.com/shuxjweb/last.git。

Pretraining is a dominant paradigm in computer vision. Generally, supervised ImageNet pretraining is commonly used to initialize the backbones of person re-identification (Re-ID) models. However, recent works show a surprising result that CNN-based pretraining on ImageNet has limited impacts on Re-ID system due to the large domain gap between ImageNet and person Re-ID data. To seek an alternative to traditional pretraining, here we investigate semantic-based pretraining as another method to utilize additional textual data against ImageNet pretraining. Specifically, we manually construct a diversified FineGPR-C caption dataset for the first time on person Re-ID events. Based on it, a pure semantic-based pretraining approach named VTBR is proposed to adopt dense captions to learn visual representations with fewer images. We train convolutional neural networks from scratch on the captions of FineGPR-C dataset, and then transfer them to downstream Re-ID tasks. Comprehensive experiments conducted on benchmark datasets show that our VTBR can achieve competitive performance compared with ImageNet pretraining - despite using up to 1.4x fewer images, revealing its potential in Re-ID pretraining.

Although the performance of person Re-Identification (ReID) has been significantly boosted, many challenging issues in real scenarios have not been fully investigated, e.g., the complex scenes and lighting variations, viewpoint and pose changes, and the large number of identities in a camera network. To facilitate the research towards conquering those issues, this paper contributes a new dataset called MSMT17 with many important features, e.g., 1) the raw videos are taken by an 15-camera network deployed in both indoor and outdoor scenes, 2) the videos cover a long period of time and present complex lighting variations, and 3) it contains currently the largest number of annotated identities, i.e., 4,101 identities and 126,441 bounding boxes. We also observe that, domain gap commonly exists between datasets, which essentially causes severe performance drop when training and testing on different datasets. This results in that available training data cannot be effectively leveraged for new testing domains. To relieve the expensive costs of annotating new training samples, we propose a Person Transfer Generative Adversarial Network (PTGAN) to bridge the domain gap. Comprehensive experiments show that the domain gap could be substantially narrowed-down by the PTGAN.

最近，由于受监督人员重新识别（REID）的表现不佳，域名概括（DG）人REID引起了很多关注，旨在学习一个不敏感的模型，并可以抵抗域的影响偏见。在本文中，我们首先通过实验验证样式因素是域偏差的重要组成部分。基于这个结论，我们提出了一种样式变量且无关紧要的学习方法（SVIL）方法，以消除样式因素对模型的影响。具体来说，我们在SVIL中设计了样式的抖动模块（SJM）。 SJM模块可以丰富特定源域的样式多样性，并减少各种源域的样式差异。这导致该模型重点关注与身份相关的信息，并对样式变化不敏感。此外，我们将SJM模块与元学习算法有机结合，从而最大程度地提高了好处并进一步提高模型的概括能力。请注意，我们的SJM模块是插件和推理，无需成本。广泛的实验证实了我们的SVIL的有效性，而我们的方法的表现优于DG-REID基准测试的最先进方法。

从图像中学习代表，健壮和歧视性信息对于有效的人重新识别（RE-ID）至关重要。在本文中，我们提出了一种基于身体和手部图像的人重新ID的端到端判别深度学习的复合方法。我们仔细设计了本地感知的全球注意力网络（Laga-Net），这是一个多分支深度网络架构，由一个用于空间注意力的分支组成，一个用于渠道注意。注意分支集中在图像的相关特征上，同时抑制了无关紧要的背景。为了克服注意力机制的弱点，与像素改组一样，我们将相对位置编码整合到空间注意模块中以捕获像素的空间位置。全球分支机构打算保留全球环境或结构信息。对于打算捕获细粒度信息的本地分支，我们进行统一的分区以水平在Conv-Layer上生成条纹。我们通过执行软分区来检索零件，而无需明确分区图像或需要外部线索，例如姿势估计。一组消融研究表明，每个组件都会有助于提高拉加网络的性能。对四个受欢迎的人体重新ID基准和两个公开可用的手数据集的广泛评估表明，我们的建议方法始终优于现有的最新方法。

This paper contributes a new high quality dataset for person re-identification, named "Market-1501". Generally, current datasets: 1) are limited in scale; 2) consist of hand-drawn bboxes, which are unavailable under realistic settings; 3) have only one ground truth and one query image for each identity (close environment). To tackle these problems, the proposed Market-1501 dataset is featured in three aspects. First, it contains over 32,000 annotated bboxes, plus a distractor set of over 500K images, making it the largest person re-id dataset to date. Second, images in Market-1501 dataset are produced using the Deformable Part Model (DPM) as pedestrian detector. Third, our dataset is collected in an open system, where each identity has multiple images under each camera.As a minor contribution, inspired by recent advances in large-scale image search, this paper proposes an unsupervised Bag-of-Words descriptor. We view person reidentification as a special task of image search. In experiment, we show that the proposed descriptor yields competitive accuracy on VIPeR, CUHK03, and Market-1501 datasets, and is scalable on the large-scale 500k dataset.

在将人重新识别（REID）模型部署在安全关键型应用程序中时，它是关键，以了解模型的鲁棒性，以反对不同的图像损坏阵列。但是，当前对人的评估Reid仅考虑干净数据集的性能，并忽略各种损坏方案中的图像。在这项工作中，我们全面建立了六种Reid基准，用于学习腐败不变的代表。在Reid领域，我们是第一个在单个和跨模式数据集中开展腐败腐败的彻底研究，包括市场-1501，CUHK03，MSMT17，REGDB，SYSU-MM01。在再现和检查最近的REID方法的鲁棒性能后，我们有一些观察结果：1）基于变压器的模型对损坏的图像更加强大，与基于CNN的模型相比，2）增加了随机擦除的概率（常用的增强方法）伤害模型腐败鲁棒性，3）交叉数据集泛化改善腐败鲁棒性增加。通过分析上述观察，我们提出了一个强大的基线，对单一和跨型号的内部数据集，实现了对不同腐败的改善的鲁棒性。我们的代码可在https://github.com/minghuichen43/cil -reid上获得。

人重新识别（Reid）旨在从不同摄像机捕获的图像中检索一个人。对于基于深度学习的REID方法，已经证明，使用本地特征与人物图像的全局特征可以帮助为人员检索提供强大的特征表示。人类的姿势信息可以提供人体骨架的位置，有效地指导网络在这些关键领域更加关注这些关键领域，也可能有助于减少来自背景或闭塞的噪音分散。然而，先前与姿势相关的作品提出的方法可能无法充分利用姿势信息的好处，并没有考虑不同当地特征的不同贡献。在本文中，我们提出了一种姿势引导图注意网络，一个多分支架构，包括一个用于全局特征的一个分支，一个用于中粒体特征的一个分支，一个分支用于细粒度关键点特征。我们使用预先训练的姿势估计器来生成本地特征学习的关键点热图，并仔细设计图表卷积层以通过建模相似关系来重新评估提取的本地特征的贡献权重。实验结果表明我们对歧视特征学习的方法的有效性，我们表明我们的模型在几个主流评估数据集上实现了最先进的表演。我们还对我们的网络进行了大量的消融研究和设计不同类型的比较实验，以证明其有效性和鲁棒性，包括整体数据集，部分数据集，遮挡数据集和跨域测试。

The combination of global and partial features has been an essential solution to improve discriminative performances in person re-identification (Re-ID) tasks. Previous part-based methods mainly focus on locating regions with specific pre-defined semantics to learn local representations, which increases learning difficulty but not efficient or robust to scenarios with large variances. In this paper, we propose an end-to-end feature learning strategy integrating discriminative information with various granularities. We carefully design the Multiple Granularity Network (MGN), a multi-branch deep network architecture consisting of one branch for global feature representations and two branches for local feature representations. Instead of learning on semantic regions, we uniformly partition the images into several stripes, and vary the number of parts in different local branches to obtain local feature representations with multiple granularities. Comprehensive experiments implemented on the mainstream evaluation datasets including Market-1501, DukeMTMC-reid and CUHK03 indicate that our method robustly achieves state-of-the-art performances and outperforms any existing approaches by a large margin. For example, on Market-1501 dataset in single query mode, we obtain a top result of Rank-1/mAP=96.6%/94.2% with this method after re-ranking.

In this paper, we are interested in learning a generalizable person re-identification (re-ID) representation from unlabeled videos. Compared with 1) the popular unsupervised re-ID setting where the training and test sets are typically under the same domain, and 2) the popular domain generalization (DG) re-ID setting where the training samples are labeled, our novel scenario combines their key challenges: the training samples are unlabeled, and collected form various domains which do no align with the test domain. In other words, we aim to learn a representation in an unsupervised manner and directly use the learned representation for re-ID in novel domains. To fulfill this goal, we make two main contributions: First, we propose Cycle Association (CycAs), a scalable self-supervised learning method for re-ID with low training complexity; and second, we construct a large-scale unlabeled re-ID dataset named LMP-video, tailored for the proposed method. Specifically, CycAs learns re-ID features by enforcing cycle consistency of instance association between temporally successive video frame pairs, and the training cost is merely linear to the data size, making large-scale training possible. On the other hand, the LMP-video dataset is extremely large, containing 50 million unlabeled person images cropped from over 10K Youtube videos, therefore is sufficient to serve as fertile soil for self-supervised learning. Trained on LMP-video, we show that CycAs learns good generalization towards novel domains. The achieved results sometimes even outperform supervised domain generalizable models. Remarkably, CycAs achieves 82.2% Rank-1 on Market-1501 and 49.0% Rank-1 on MSMT17 with zero human annotation, surpassing state-of-the-art supervised DG re-ID methods. Moreover, we also demonstrate the superiority of CycAs under the canonical unsupervised re-ID and the pretrain-and-finetune scenarios.