Supervision for metric learning has long been given in the form of equivalence between human-labeled classes. Although this type of supervision has been a basis of metric learning for decades, we argue that it hinders further advances of the field. In this regard, we propose a new regularization method, dubbed HIER, to discover the latent semantic hierarchy of training data, and to deploy the hierarchy to provide richer and more fine-grained supervision than inter-class separability induced by common metric learning losses. HIER achieved this goal with no annotation for the semantic hierarchy but by learning hierarchical proxies in hyperbolic spaces. The hierarchical proxies are learnable parameters, and each of them is trained to serve as an ancestor of a group of data or other proxies to approximate the semantic hierarchy among them. HIER deals with the proxies along with data in hyperbolic space since geometric properties of the space are well-suited to represent their hierarchical structure. The efficacy of HIER was evaluated on four standard benchmarks, where it consistently improved performance of conventional methods when integrated with them, and consequently achieved the best records, surpassing even the existing hyperbolic metric learning technique, in almost all settings.

深度度量学习（DML）模型通常需要强大的本地和全球表示，但是，DML模型培训中的本地和全球特征的有效整合是一项挑战。 DML模型通常具有特定损耗功能，包括基于成对和基于代理的损失。基于成对的损耗函数利用数据点之间丰富的语义关系，然而，在DML模型训练期间经常遭受缓慢的收敛。另一方面，基于代理的损耗功能通常会导致培训期间收敛的显着加速，而基于代理的损失通常不会完全探索数据点之间的丰富关系。在本文中，我们提出了一种新的DML方法来解决这些挑战。所提出的DML方法通过集成对基于基于代理的损耗函数来利用丰富的数据到数据关系以及快速收敛来利用混合丢失来利用混合丢失。此外，所提出的DML方法利用全局和本地功能在DML模型培训中获得丰富的表示。最后，我们还使用二阶注意功能增强，以提高准确和有效的检索。在我们的实验中，我们在四个公共基准中广泛评估了所提出的DML方法，实验结果表明，该方法在所有基准上实现了最先进的性能。

3D对象的点云具有固有的组成性质，可以将简单的部分组装成逐渐复杂的形状以形成整个对象。明确捕获这种部分整体层次结构是一个长期的目标，以建立有效的模型，但其树状的性质使这项任务变得难以捉摸。在本文中，我们建议将点云分类器的特征嵌入双曲线空间中，并明确规范空间以说明零件整体结构。双曲线空间是唯一可以成功嵌入层次结构的树状性质的空间。这导致了对点云分类的最先进的监督模型的性能的实质性改善。

深度度量学习（DML）有助于学习嵌入功能，以将语义上的数据投射到附近的嵌入空间中，并在许多应用中起着至关重要的作用，例如图像检索和面部识别。但是，DML方法的性能通常很大程度上取决于采样方法，从训练中的嵌入空间中选择有效的数据。实际上，嵌入空间中的嵌入是通过一些深层模型获得的，其中嵌入空间通常由于缺乏训练点而在贫瘠的区域中，导致所谓的“缺失嵌入”问题。此问题可能会损害样品质量，从而导致DML性能退化。在这项工作中，我们研究了如何减轻“缺失”问题以提高采样质量并实现有效的DML。为此，我们提出了一个密集锚定的采样（DAS）方案，该方案将嵌入的数据点视为“锚”，并利用锚附近的嵌入空间来密集地生成无数据点的嵌入。具体而言，我们建议用判别性特征缩放（DFS）和多个锚点利用单个锚周围的嵌入空间，并具有记忆转换转换（MTS）。通过这种方式，通过有或没有数据点的嵌入方式，我们能够提供更多的嵌入以促进采样过程，从而提高DML的性能。我们的方法毫不费力地集成到现有的DML框架中，并在没有铃铛和哨声的情况下改进了它们。在三个基准数据集上进行的广泛实验证明了我们方法的优势。

Learning the distance metric between pairs of examples is of great importance for learning and visual recognition. With the remarkable success from the state of the art convolutional neural networks, recent works [1, 31] have shown promising results on discriminatively training the networks to learn semantic feature embeddings where similar examples are mapped close to each other and dissimilar examples are mapped farther apart. In this paper, we describe an algorithm for taking full advantage of the training batches in the neural network training by lifting the vector of pairwise distances within the batch to the matrix of pairwise distances. This step enables the algorithm to learn the state of the art feature embedding by optimizing a novel structured prediction objective on the lifted problem. Additionally, we collected Online Products dataset: 120k images of 23k classes of online products for metric learning. Our experiments on the CUB-200-2011 [37], CARS196 [19], and Online Products datasets demonstrate significant improvement over existing deep feature embedding methods on all experimented embedding sizes with the GoogLeNet [33] network.

Deep metric learning aims to learn an embedding space, where semantically similar samples are close together and dissimilar ones are repelled against. To explore more hard and informative training signals for augmentation and generalization, recent methods focus on generating synthetic samples to boost metric learning losses. However, these methods just use the deterministic and class-independent generations (e.g., simple linear interpolation), which only can cover the limited part of distribution spaces around original samples. They have overlooked the wide characteristic changes of different classes and can not model abundant intra-class variations for generations. Therefore, generated samples not only lack rich semantics within the certain class, but also might be noisy signals to disturb training. In this paper, we propose a novel intra-class adaptive augmentation (IAA) framework for deep metric learning. We reasonably estimate intra-class variations for every class and generate adaptive synthetic samples to support hard samples mining and boost metric learning losses. Further, for most datasets that have a few samples within the class, we propose the neighbor correction to revise the inaccurate estimations, according to our correlation discovery where similar classes generally have similar variation distributions. Extensive experiments on five benchmarks show our method significantly improves and outperforms the state-of-the-art methods on retrieval performances by 3%-6%. Our code is available at https://github.com/darkpromise98/IAA

A family of loss functions built on pair-based computation have been proposed in the literature which provide a myriad of solutions for deep metric learning. In this paper, we provide a general weighting framework for understanding recent pair-based loss functions. Our contributions are three-fold: (1) we establish a General Pair Weighting (GPW) framework, which casts the sampling problem of deep metric learning into a unified view of pair weighting through gradient analysis, providing a powerful tool for understanding recent pair-based loss functions; (2) we show that with GPW, various existing pair-based methods can be compared and discussed comprehensively, with clear differences and key limitations identified; (3) we propose a new loss called multi-similarity loss (MS loss) under the GPW, which is implemented in two iterative steps (i.e., mining and weighting). This allows it to fully consider three similarities for pair weighting, providing a more principled approach for collecting and weighting informative pairs. Finally, the proposed MS loss obtains new state-of-the-art performance on four image retrieval benchmarks, where it outperforms the most recent approaches, such as ABE [14] and HTL [4], by a large margin, e.g., , and 80.9% → 88.0% on In-Shop Clothes Retrieval dataset

深度指标学习旨在学习嵌入空间，即使在训练期间他们的类是看不见的，数据之间的距离反映了他们的类等价。然而，培训中可用的有限数量排除了学习嵌入空间的概括。由此激励，我们介绍了一种新的数据增强方法，该方法合成了新颖类及其嵌入向量。我们的方法可以向嵌入式模型提供丰富的语义信息，通过在原始数据中使用新类别增强培训数据来提高其泛化。我们通过学习和利用条件生成模型来实现这个想法，其中，给定类标签和噪声，产生类的随机嵌入向量。我们所提出的发电机允许损失通过增强现实和多样的类来使用更丰富的级关系，从而更好地推广了看不见的样本。公共基准数据集上的实验结果表明，我们的方法明确提高了基于代理的损失的性能。

Recent methods for deep metric learning have been focusing on designing different contrastive loss functions between positive and negative pairs of samples so that the learned feature embedding is able to pull positive samples of the same class closer and push negative samples from different classes away from each other. In this work, we recognize that there is a significant semantic gap between features at the intermediate feature layer and class labels at the final output layer. To bridge this gap, we develop a contrastive Bayesian analysis to characterize and model the posterior probabilities of image labels conditioned by their features similarity in a contrastive learning setting. This contrastive Bayesian analysis leads to a new loss function for deep metric learning. To improve the generalization capability of the proposed method onto new classes, we further extend the contrastive Bayesian loss with a metric variance constraint. Our experimental results and ablation studies demonstrate that the proposed contrastive Bayesian metric learning method significantly improves the performance of deep metric learning in both supervised and pseudo-supervised scenarios, outperforming existing methods by a large margin.

Deep Metric Learning (DML) learns a non-linear semantic embedding from input data that brings similar pairs together while keeping dissimilar data away from each other. To this end, many different methods are proposed in the last decade with promising results in various applications. The success of a DML algorithm greatly depends on its loss function. However, no loss function is perfect, and it deals only with some aspects of an optimal similarity embedding. Besides, the generalizability of the DML on unseen categories during the test stage is an important matter that is not considered by existing loss functions. To address these challenges, we propose novel approaches to combine different losses built on top of a shared deep feature extractor. The proposed ensemble of losses enforces the deep model to extract features that are consistent with all losses. Since the selected losses are diverse and each emphasizes different aspects of an optimal semantic embedding, our effective combining methods yield a considerable improvement over any individual loss and generalize well on unseen categories. Here, there is no limitation in choosing loss functions, and our methods can work with any set of existing ones. Besides, they can optimize each loss function as well as its weight in an end-to-end paradigm with no need to adjust any hyper-parameter. We evaluate our methods on some popular datasets from the machine vision domain in conventional Zero-Shot-Learning (ZSL) settings. The results are very encouraging and show that our methods outperform all baseline losses by a large margin in all datasets.

Hierarchical semantic structures, naturally existing in real-world datasets, can assist in capturing the latent distribution of data to learn robust hash codes for retrieval systems. Although hierarchical semantic structures can be simply expressed by integrating semantically relevant data into a high-level taxon with coarser-grained semantics, the construction, embedding, and exploitation of the structures remain tricky for unsupervised hash learning. To tackle these problems, we propose a novel unsupervised hashing method named Hyperbolic Hierarchical Contrastive Hashing (HHCH). We propose to embed continuous hash codes into hyperbolic space for accurate semantic expression since embedding hierarchies in hyperbolic space generates less distortion than in hyper-sphere space and Euclidean space. In addition, we extend the K-Means algorithm to hyperbolic space and perform the proposed hierarchical hyperbolic K-Means algorithm to construct hierarchical semantic structures adaptively. To exploit the hierarchical semantic structures in hyperbolic space, we designed the hierarchical contrastive learning algorithm, including hierarchical instance-wise and hierarchical prototype-wise contrastive learning. Extensive experiments on four benchmark datasets demonstrate that the proposed method outperforms the state-of-the-art unsupervised hashing methods. Codes will be released.

We address the problem of distance metric learning (DML), defined as learning a distance consistent with a notion of semantic similarity. Traditionally, for this problem supervision is expressed in the form of sets of points that follow an ordinal relationship -an anchor point x is similar to a set of positive points Y , and dissimilar to a set of negative points Z, and a loss defined over these distances is minimized. While the specifics of the optimization differ, in this work we collectively call this type of supervision Triplets and all methods that follow this pattern Triplet-Based methods. These methods are challenging to optimize. A main issue is the need for finding informative triplets, which is usually achieved by a variety of tricks such as increasing the batch size, hard or semi-hard triplet mining, etc. Even with these tricks, the convergence rate of such methods is slow. In this paper we propose to optimize the triplet loss on a different space of triplets, consisting of an anchor data point and similar and dissimilar proxy points which are learned as well. These proxies approximate the original data points, so that a triplet loss over the proxies is a tight upper bound of the original loss. This proxy-based loss is empirically better behaved. As a result, the proxy-loss improves on state-of-art results for three standard zero-shot learning datasets, by up to 15% points, while converging three times as fast as other triplet-based losses.

Although self-/un-supervised methods have led to rapid progress in visual representation learning, these methods generally treat objects and scenes using the same lens. In this paper, we focus on learning representations for objects and scenes that preserve the structure among them. Motivated by the observation that visually similar objects are close in the representation space, we argue that the scenes and objects should instead follow a hierarchical structure based on their compositionality. To exploit such a structure, we propose a contrastive learning framework where a Euclidean loss is used to learn object representations and a hyperbolic loss is used to encourage representations of scenes to lie close to representations of their constituent objects in a hyperbolic space. This novel hyperbolic objective encourages the scene-object hypernymy among the representations by optimizing the magnitude of their norms. We show that when pretraining on the COCO and OpenImages datasets, the hyperbolic loss improves downstream performance of several baselines across multiple datasets and tasks, including image classification, object detection, and semantic segmentation. We also show that the properties of the learned representations allow us to solve various vision tasks that involve the interaction between scenes and objects in a zero-shot fashion. Our code can be found at \url{https://github.com/shlokk/HCL/tree/main/HCL}.

双曲线空间可以嵌入树度量，其失真几乎没有失真，是用于建模实际数据和语义的层次结构的理想性质。虽然高维嵌入式通常会导致更好的表示，但由于非琐碎的优化以及高维双曲数据缺乏可视化，大多数双曲模型利用低维嵌入式。我们提出了CO-SNE，将欧几里德空间可视化工具T-SNE延伸到双曲线空间。像T-SNE一样，它将数据点之间的距离转换为联合概率，并尝试最小化高维数据的联合概率之间的kullback-leibler分歧$ x $和低维嵌入$ y $。然而，与欧几里德空间不同，双曲线空间不均匀：体积可能在远离原点的位置包含更多点。因此，CO-SNE为$ x $和hyberbolic \ Underline {c} auchy而不是t-sne的学生的t分布，而不是$ y $，它还试图将$ x $的单个距离保存到\下划线{o} RIGIN $ Y $。我们将Co-SNE施加到高维双曲生物数据以及无监督的双曲线表现。我们的结果表明，CO-SNE将高维色双曲数据降低到低维空间，而不会失去双曲线特性，显着优于PCA，T-SNE，UMAP和HOROPCA等流行可视化工具，其最后一个专门设计用于双曲数据。

Deep embeddings answer one simple question: How similar are two images? Learning these embeddings is the bedrock of verification, zero-shot learning, and visual search. The most prominent approaches optimize a deep convolutional network with a suitable loss function, such as contrastive loss or triplet loss. While a rich line of work focuses solely on the loss functions, we show in this paper that selecting training examples plays an equally important role. We propose distance weighted sampling, which selects more informative and stable examples than traditional approaches. In addition, we show that a simple margin based loss is sufficient to outperform all other loss functions. We evaluate our approach on the Stanford Online Products, CAR196, and the CUB200-2011 datasets for image retrieval and clustering, and on the LFW dataset for face verification. Our method achieves state-of-the-art performance on all of them.

Knowledge distillation aims at transferring knowledge acquired in one model (a teacher) to another model (a student) that is typically smaller. Previous approaches can be expressed as a form of training the student to mimic output activations of individual data examples represented by the teacher. We introduce a novel approach, dubbed relational knowledge distillation (RKD), that transfers mutual relations of data examples instead. For concrete realizations of RKD, we propose distance-wise and angle-wise distillation losses that penalize structural differences in relations. Experiments conducted on different tasks show that the proposed method improves educated student models with a significant margin. In particular for metric learning, it allows students to outperform their teachers' performance, achieving the state of the arts on standard benchmark datasets.

深度度量学习（DML）了解映射，该映射到嵌入空间，其中类似数据接近并且不同的数据远远。然而，DML的传统基于代理的损失有两个问题：渐变问题并使用多个本地中心应用现实世界数据集。此外，DML性能指标也有一些问题具有稳定性和灵活性。本文提出了多代理锚（MPA）丢失和归一化折扣累积增益（NDCG @ K）度量。本研究贡献了三个以下：（1）MPA损失能够使用多代理学习现实世界数据集。（2）MPA损失提高了神经网络的培训能力，解决了梯度问题。（3）NDCG @ K度量标准鼓励对各种数据集进行全面评估。最后，我们展示了MPA损失的有效性，MPA损失在两个用于细粒度图像的数据集上实现了最高准确性。

Although existing semi-supervised learning models achieve remarkable success in learning with unannotated in-distribution data, they mostly fail to learn on unlabeled data sampled from novel semantic classes due to their closed-set assumption. In this work, we target a pragmatic but under-explored Generalized Novel Category Discovery (GNCD) setting. The GNCD setting aims to categorize unlabeled training data coming from known and novel classes by leveraging the information of partially labeled known classes. We propose a two-stage Contrastive Affinity Learning method with auxiliary visual Prompts, dubbed PromptCAL, to address this challenging problem. Our approach discovers reliable pairwise sample affinities to learn better semantic clustering of both known and novel classes for the class token and visual prompts. First, we propose a discriminative prompt regularization loss to reinforce semantic discriminativeness of prompt-adapted pre-trained vision transformer for refined affinity relationships. Besides, we propose a contrastive affinity learning stage to calibrate semantic representations based on our iterative semi-supervised affinity graph generation method for semantically-enhanced prompt supervision. Extensive experimental evaluation demonstrates that our PromptCAL method is more effective in discovering novel classes even with limited annotations and surpasses the current state-of-the-art on generic and fine-grained benchmarks (with nearly $11\%$ gain on CUB-200, and $9\%$ on ImageNet-100) on overall accuracy.

从有限的例子中学习和推广，我，e，几次拍摄的学习，对许多真实世界视觉应用的核心重要性是核心重要性。实现少量学习的主要方法是实现来自不同类别的样本是独特的嵌入的嵌入。最近的研究表明，通过双曲线几何嵌入较低的分层和结构化数据，使其适合几次拍摄的学习。在本文中，我们建议学习上下文知识的双曲标准，以表征与学习集合的点与设置距离相关联的点之间的距离。为此，我们将度量标准作为双曲线空间的切线束上的加权总和，并制定自适应地并基于点的星座获得重量的机制。这不仅使得公制本地，而且依赖于手头的任务，这意味着度量根据它比较的样本。我们经验证明，这种度量在异常值存在下产生鲁棒性，并实现基线模型的切实改善。这包括五个流行的少量分类基准，即迷你想象，分层 - 想象成，CALTECH-UCSD鸟-200-2011（幼崽），CIFAR-FS和FC100的最先进的结果。

最近的工作据称，利用Softmax跨熵的分类损失不仅可以用于固定设定的分类任务，而且还通过专门为开放式任务开发的优于开销的损失，包括几次射击学习和检索。使用不同的嵌入几何形状研究了软MAX分类器 - 欧几里德，双曲线和球形，并且已经对一个或另一个的优越性进行了索赔，但它们没有得到精心控制的系统。我们对各种固定设定分类和图像检索任务的软MAX损失嵌入几何的实证研究。对于球形损失观察到的一个有趣的财产导致我们提出了一种基于VON MISES-FISHER分配的概率分类器，我们表明它具有最先进的方法竞争，同时生产出完善的盒子校准。我们提供有关亏损之间的权衡以及如何在其中选择的指导。