Unsupervised Domain Adaptation (UDA) is an effective approach to tackle the issue of domain shift. Specifically, UDA methods try to align the source and target representations to improve the generalization on the target domain. Further, UDA methods work under the assumption that the source data is accessible during the adaptation process. However, in real-world scenarios, the labelled source data is often restricted due to privacy regulations, data transmission constraints, or proprietary data concerns. The Source-Free Domain Adaptation (SFDA) setting aims to alleviate these concerns by adapting a source-trained model for the target domain without requiring access to the source data. In this paper, we explore the SFDA setting for the task of adaptive object detection. To this end, we propose a novel training strategy for adapting a source-trained object detector to the target domain without source data. More precisely, we design a novel contrastive loss to enhance the target representations by exploiting the objects relations for a given target domain input. These object instance relations are modelled using an Instance Relation Graph (IRG) network, which are then used to guide the contrastive representation learning. In addition, we utilize a student-teacher based knowledge distillation strategy to avoid overfitting to the noisy pseudo-labels generated by the source-trained model. Extensive experiments on multiple object detection benchmark datasets show that the proposed approach is able to efficiently adapt source-trained object detectors to the target domain, outperforming previous state-of-the-art domain adaptive detection methods. Code is available at https://github.com/Vibashan/irg-sfda.

我们解决对象检测中的域适应问题，其中在源（带有监控）和目标域（没有监督的域的域名）之间存在显着的域移位。作为广泛采用的域适应方法，自培训教师学生框架（学生模型从教师模型生成的伪标签学习）在目标域中产生了显着的精度增益。然而，由于其偏向源域，它仍然存在从教师产生的大量低质量伪标签（例如，误报）。为了解决这个问题，我们提出了一种叫做自适应无偏见教师（AUT）的自我训练框架，利用对抗的对抗学习和弱强的数据增强来解决域名。具体而言，我们在学生模型中使用特征级的对抗性培训，确保从源和目标域中提取的功能共享类似的统计数据。这使学生模型能够捕获域不变的功能。此外，我们在目标领域的教师模型和两个域上的学生模型之间应用了弱强的增强和相互学习。这使得教师模型能够从学生模型中逐渐受益，而不会遭受域移位。我们展示了AUT通过大边距显示所有现有方法甚至Oracle（完全监督）模型的优势。例如，我们在有雾的城市景观（Clipart1k）上实现了50.9％（49.3％）地图，分别比以前的最先进和甲骨文高9.2％（5.2％）和8.2％（11.0％）

Domain adaptive detection aims to improve the generalization of detectors on target domain. To reduce discrepancy in feature distributions between two domains, recent approaches achieve domain adaption through feature alignment in different granularities via adversarial learning. However, they neglect the relationship between multiple granularities and different features in alignment, degrading detection. Addressing this, we introduce a unified multi-granularity alignment (MGA)-based detection framework for domain-invariant feature learning. The key is to encode the dependencies across different granularities including pixel-, instance-, and category-levels simultaneously to align two domains. Specifically, based on pixel-level features, we first develop an omni-scale gated fusion (OSGF) module to aggregate discriminative representations of instances with scale-aware convolutions, leading to robust multi-scale detection. Besides, we introduce multi-granularity discriminators to identify where, either source or target domains, different granularities of samples come from. Note that, MGA not only leverages instance discriminability in different categories but also exploits category consistency between two domains for detection. Furthermore, we present an adaptive exponential moving average (AEMA) strategy that explores model assessments for model update to improve pseudo labels and alleviate local misalignment problem, boosting detection robustness. Extensive experiments on multiple domain adaption scenarios validate the superiority of MGA over other approaches on FCOS and Faster R-CNN detectors. Code will be released at https://github.com/tiankongzhang/MGA.

Semi-supervised object detection (SSOD) aims to boost detection performance by leveraging extra unlabeled data. The teacher-student framework has been shown to be promising for SSOD, in which a teacher network generates pseudo-labels for unlabeled data to assist the training of a student network. Since the pseudo-labels are noisy, filtering the pseudo-labels is crucial to exploit the potential of such framework. Unlike existing suboptimal methods, we propose a two-step pseudo-label filtering for the classification and regression heads in a teacher-student framework. For the classification head, OCL (Object-wise Contrastive Learning) regularizes the object representation learning that utilizes unlabeled data to improve pseudo-label filtering by enhancing the discriminativeness of the classification score. This is designed to pull together objects in the same class and push away objects from different classes. For the regression head, we further propose RUPL (Regression-Uncertainty-guided Pseudo-Labeling) to learn the aleatoric uncertainty of object localization for label filtering. By jointly filtering the pseudo-labels for the classification and regression heads, the student network receives better guidance from the teacher network for object detection task. Experimental results on Pascal VOC and MS-COCO datasets demonstrate the superiority of our proposed method with competitive performance compared to existing methods.

最近，检测变压器（DETR）是一种端到端对象检测管道，已达到有希望的性能。但是，它需要大规模标记的数据，并遭受域移位，尤其是当目标域中没有标记的数据时。为了解决这个问题，我们根据平均教师框架MTTRANS提出了一个端到端的跨域检测变压器，该变压器可以通过伪标签充分利用对象检测训练中未标记的目标域数据和在域之间的传输知识中的传输知识。我们进一步提出了综合的多级特征对齐方式，以改善由平均教师框架生成的伪标签，利用跨尺度的自我注意事项机制在可变形的DETR中。图像和对象特征在本地，全局和实例级别与基于域查询的特征对齐（DQFA），基于BI级的基于图形的原型对齐（BGPA）和Wine-Wise图像特征对齐（TIFA）对齐。另一方面，未标记的目标域数据伪标记，可用于平均教师框架的对象检测训练，可以导致更好的特征提取和对齐。因此，可以根据变压器的架构对迭代和相互优化的平均教师框架和全面的多层次特征对齐。广泛的实验表明，我们提出的方法在三个领域适应方案中实现了最先进的性能，尤其是SIM10K到CityScapes方案的结果，从52.6地图提高到57.9地图。代码将发布。

Domain adaptive object detection (DAOD) aims to alleviate transfer performance degradation caused by the cross-domain discrepancy. However, most existing DAOD methods are dominated by computationally intensive two-stage detectors, which are not the first choice for industrial applications. In this paper, we propose a novel semi-supervised domain adaptive YOLO (SSDA-YOLO) based method to improve cross-domain detection performance by integrating the compact one-stage detector YOLOv5 with domain adaptation. Specifically, we adapt the knowledge distillation framework with the Mean Teacher model to assist the student model in obtaining instance-level features of the unlabeled target domain. We also utilize the scene style transfer to cross-generate pseudo images in different domains for remedying image-level differences. In addition, an intuitive consistency loss is proposed to further align cross-domain predictions. We evaluate our proposed SSDA-YOLO on public benchmarks including PascalVOC, Clipart1k, Cityscapes, and Foggy Cityscapes. Moreover, to verify its generalization, we conduct experiments on yawning detection datasets collected from various classrooms. The results show considerable improvements of our method in these DAOD tasks. Our code is available on \url{https://github.com/hnuzhy/SSDA-YOLO}.

大多数现有的域自适应对象检测方法利用对抗特征对齐，以使模型适应新域。对抗性特征比对的最新进展旨在减少发生的负面影响或负转移的负面影响，因为特征的分布取决于对象类别。但是，通过分析无锚的一阶段检测器的特征，在本文中，我们发现可能发生负转移，因为特征分布取决于对边界框的回归值以及类别的回归值而变化。为了通过解决此问题来获得域的不变性，我们考虑了特征分布的模式，以偏移值为条件。通过一种非常简单有效的调节方法，我们提出了在各种实验环境中实现最新性能的OADA（偏置感知域自适应对象检测器）。此外，通过通过单数值分析分析，我们发现我们的模型可以增强可区分性和可传递性。

在这项工作中，我们提出了Cluda，这是一种简单而又新颖的方法，用于通过将对比损失纳入学生教师学习范式中，以进行语义分割，以进行语义分割，以利用伪标记，以通过伪标记产生的伪标记。教师网络。更具体地说，我们从编码器中提取多级融合功能图，并通过图像的源目标混合使用不同类别和不同域的对比度损失。我们始终提高各种特征编码器体系结构和语义分割中不同域适应数据集的性能。此外，我们引入了一种学识渊博的对比损失，以改善UDA最先进的多分辨率训练方法。我们在gta $ \ rightarrow $ cityScapes（74.4 miou，+0.6）和Synthia $ \ rightarrow $ cityScapes（67.2 miou，+1.4）数据集上产生最先进的结果。 Cluda有效地证明了UDA中的对比度学习是一种通用方法，可以轻松地将其集成到任何现有的UDA中以进行语义分割任务。有关实施的详细信息，请参考补充材料。

域自适应对象检测（DAOD）旨在改善探测和测试数据来自不同域时的探测器的泛化能力。考虑到显着的域间隙，一些典型方法，例如基于Conscangan的方法，采用中间域来逐步地桥接源域和靶域。然而，基于Conscangan的中间域缺少对象检测的PIX或实例级监控，这导致语义差异。为了解决这个问题，在本文中，我们介绍了具有四种不同的低频滤波器操作的频谱增强一致性（FSAC）框架。通过这种方式，我们可以获得一系列增强数据作为中间域。具体地，我们提出了一种两级优化框架。在第一阶段，我们利用所有原始和增强的源数据来训练对象检测器。在第二阶段，采用增强源和目标数据，具有伪标签来执行预测一致性的自培训。使用均值优化的教师模型用于进一步修改伪标签。在实验中，我们分别评估了我们在单一和复合目标DAOD上的方法，这证明了我们方法的有效性。

无监督的域适配旨在对齐标记的源域和未标记的目标域，但需要访问源数据，这些源数据通常会提高数据隐私，数据便携性和数据传输效率。我们研究无监督的模型适应（UMA），或者在没有源数据的情况下称为无监督域适应，旨在使源训练模型适应目标分布而不访问源数据的替代设置。为此，我们设计了一种创新的历史对比学习（HCL）技术，利用历史来源假设来弥补UMA中的源数据。 HCL从两个角度来解决UMA挑战。首先，它介绍了通过由当前适应的模型和历史模型产生的嵌入来对目标样本学习的历史对比实例歧视（HCID）。通过历史模型，HCID鼓励UMA学习案例鉴别的目标表示，同时保留源假设。其次，它介绍了伪标签目标样本的历史对比类别歧视（HCCD）以学习类别鉴别的目标表示。具体而言，HCCD根据当前和历史模型的预测一致重新重量伪标签。广泛的实验表明，HCL优于各种视觉任务和设置始终如一地呈现和最先进的方法。

尽管他们最近取得了成功，但在测试时遇到分配变化时，深层神经网络仍会继续表现不佳。最近，许多提出的方法试图通过将模型与推理之前的新分布对齐来解决。由于没有可用的标签，因此需要无监督的目标才能使模型适应观察到的测试数据。在本文中，我们提出了测试时间自我训练（测试）：一种技术，该技术在测试时以某些源数据和新的数据分配为输入，并使用学生教师框架来学习不变且强大的表示形式。 。我们发现使用测试适应的模型可以显着改善基线测试时间适应算法。测试可以实现现代领域适应算法的竞争性能，同时自适应时访问5-10倍的数据。我们对两项任务进行了各种基准：对象检测和图像分割，并发现该模型适用于测试。我们发现测试设置了用于测试时间域适应算法的新最新技术。

We propose an approach for unsupervised adaptation of object detectors from label-rich to label-poor domains which can significantly reduce annotation costs associated with detection. Recently, approaches that align distributions of source and target images using an adversarial loss have been proven effective for adapting object classifiers. However, for object detection, fully matching the entire distributions of source and target images to each other at the global image level may fail, as domains could have distinct scene layouts and different combinations of objects. On the other hand, strong matching of local features such as texture and color makes sense, as it does not change category level semantics. This motivates us to propose a novel method for detector adaptation based on strong local alignment and weak global alignment. Our key contribution is the weak alignment model, which focuses the adversarial alignment loss on images that are globally similar and puts less emphasis on aligning images that are globally dissimilar. Additionally, we design the strong domain alignment model to only look at local receptive fields of the feature map. We empirically verify the effectiveness of our method on four datasets comprising both large and small domain shifts. Our code is available at https://github.com/ VisionLearningGroup/DA_Detection.

虽然监督语义分割存在重大进展，但由于领域偏差，将分段模型部署到解除域来仍然具有挑战性。域适应可以通过将知识从标记的源域传输到未标记的目标域来帮助。以前的方法通常尝试执行对全局特征的适应，然而，通常忽略要计入特征空间中的每个像素的本地语义附属机构，导致较少的可辨性。为解决这个问题，我们提出了一种用于细粒度阶级对齐的新型语义原型对比学习框架。具体地，语义原型提供了用于每个像素鉴别的表示学习的监控信号，并且需要在特征空间中的源极和目标域的每个像素来反映相应的语义原型的内容。通过这种方式，我们的框架能够明确地制作较近的类别的像素表示，并且进一步越来越多地分开，以改善分割模型的鲁棒性以及减轻域移位问题。与最先进的方法相比，我们的方法易于实施并达到优异的结果，如众多实验所展示的那样。代码在[此HTTPS URL]（https://github.com/binhuixie/spcl）上公开可用。

无监督域自适应对象检测的自我训练是一项艰巨的任务，其性能在很大程度上取决于伪盒的质量。尽管结果有令人鼓舞，但先前的工作在很大程度上忽略了自训练期间伪箱的不确定性。在本文中，我们提出了一个简单而有效的框架，称为概率教师（PT），该框架旨在从逐渐发展的教师中捕获未标记的目标数据的不确定性，并以互惠互利的方式指导学生学习学生。具体而言，我们建议利用不确定性引导的一致性训练来促进分类适应和本地化适应，而不是通过精心设计的置信度阈值过滤伪盒。此外，我们与定位适应同时进行锚定适应性，因为锚被视为可学习的参数。与此框架一起，我们还提出了一种新颖的熵局灶性损失（EFL），以进一步促进不确定性引导的自我训练。配备了EFL，PT的表现优于所有以前的基线，并实现了新的最先进。

深度学习的快速发展在分割方面取得了长足的进步，这是计算机视觉的基本任务之一。但是，当前的细分算法主要取决于像素级注释的可用性，这些注释通常昂贵，乏味且费力。为了减轻这一负担，过去几年见证了越来越多的关注，以建立标签高效，深度学习的细分算法。本文对标签有效的细分方法进行了全面的审查。为此，我们首先根据不同类型的弱标签提供的监督（包括没有监督，粗略监督，不完整的监督和嘈杂的监督和嘈杂的监督），首先开发出一种分类法来组织这些方法，并通过细分类型（包括语义细分）补充，实例分割和全景分割）。接下来，我们从统一的角度总结了现有的标签有效的细分方法，该方法讨论了一个重要的问题：如何弥合弱监督和密集预测之间的差距 - 当前的方法主要基于启发式先导，例如交叉像素相似性，跨标签约束，跨视图一致性，跨图像关系等。最后，我们分享了对标签有效深层细分的未来研究方向的看法。

Unsupervised source-free domain adaptation methods aim to train a model to be used in the target domain utilizing the pretrained source-domain model and unlabeled target-domain data, where the source data may not be accessible due to intellectual property or privacy issues. These methods frequently utilize self-training with pseudo-labeling thresholded by prediction confidence. In a source-free scenario, only supervision comes from target data, and thresholding limits the contribution of the self-training. In this study, we utilize self-training with a mean-teacher approach. The student network is trained with all predictions of the teacher network. Instead of thresholding the predictions, the gradients calculated from the pseudo-labels are weighted based on the reliability of the teacher's predictions. We propose a novel method that uses proxy-based metric learning to estimate reliability. We train a metric network on the encoder features of the teacher network. Since the teacher is updated with the moving average, the encoder feature space is slowly changing. Therefore, the metric network can be updated in training time, which enables end-to-end training. We also propose a metric-based online ClassMix method to augment the input of the student network where the patches to be mixed are decided based on the metric reliability. We evaluated our method in synthetic-to-real and cross-city scenarios. The benchmarks show that our method significantly outperforms the existing state-of-the-art methods.

语义分割在广泛的计算机视觉应用中起着基本作用，提供了全球对图像​​的理解的关键信息。然而，最先进的模型依赖于大量的注释样本，其比在诸如图像分类的任务中获得更昂贵的昂贵的样本。由于未标记的数据替代地获得更便宜，因此无监督的域适应达到了语义分割社区的广泛成功并不令人惊讶。本调查致力于总结这一令人难以置信的快速增长的领域的五年，这包含了语义细分本身的重要性，以及将分段模型适应新环境的关键需求。我们提出了最重要的语义分割方法;我们对语义分割的域适应技术提供了全面的调查;我们揭示了多域学习，域泛化，测试时间适应或无源域适应等较新的趋势;我们通过描述在语义细分研究中最广泛使用的数据集和基准测试来结束本调查。我们希望本调查将在学术界和工业中提供具有全面参考指导的研究人员，并有助于他们培养现场的新研究方向。

Object detection typically assumes that training and test data are drawn from an identical distribution, which, however, does not always hold in practice. Such a distribution mismatch will lead to a significant performance drop. In this work, we aim to improve the cross-domain robustness of object detection. We tackle the domain shift on two levels: 1) the image-level shift, such as image style, illumination, etc., and 2) the instance-level shift, such as object appearance, size, etc. We build our approach based on the recent state-of-the-art Faster R-CNN model, and design two domain adaptation components, on image level and instance level, to reduce the domain discrepancy. The two domain adaptation components are based on H-divergence theory, and are implemented by learning a domain classifier in adversarial training manner. The domain classifiers on different levels are further reinforced with a consistency regularization to learn a domain-invariant region proposal network (RPN) in the Faster R-CNN model. We evaluate our newly proposed approach using multiple datasets including Cityscapes, KITTI, SIM10K, etc. The results demonstrate the effectiveness of our proposed approach for robust object detection in various domain shift scenarios.

零拍摄对象检测（ZSD），将传统检测模型扩展到检测来自Unseen类别的对象的任务，已成为计算机视觉中的新挑战。大多数现有方法通过严格的映射传输策略来解决ZSD任务，这可能导致次优ZSD结果：1）这些模型的学习过程忽略了可用的看不见的类信息，因此可以轻松地偏向所看到的类别; 2）原始视觉特征空间并不合适，缺乏歧视信息。为解决这些问题，我们开发了一种用于ZSD的新型语义引导的对比网络，命名为Contrastzsd，一种检测框架首先将对比学习机制带入零拍摄检测的领域。特别地，对比度包括两个语义导向的对比学学习子网，其分别与区域类别和区域区域对之间形成对比。成对对比度任务利用从地面真理标签和预定义的类相似性分布派生的附加监督信号。在那些明确的语义监督的指导下，模型可以了解更多关于看不见的类别的知识，以避免看到概念的偏见问题，同时优化视觉功能的数据结构，以更好地辨别更好的视觉语义对齐。广泛的实验是在ZSD，即Pascal VOC和MS Coco的两个流行基准上进行的。结果表明，我们的方法优于ZSD和广义ZSD任务的先前最先进的。

Domain adaptation aims to bridge the domain shifts between the source and the target domain. These shifts may span different dimensions such as fog, rainfall, etc. However, recent methods typically do not consider explicit prior knowledge about the domain shifts on a specific dimension, thus leading to less desired adaptation performance. In this paper, we study a practical setting called Specific Domain Adaptation (SDA) that aligns the source and target domains in a demanded-specific dimension. Within this setting, we observe the intra-domain gap induced by different domainness (i.e., numerical magnitudes of domain shifts in this dimension) is crucial when adapting to a specific domain. To address the problem, we propose a novel Self-Adversarial Disentangling (SAD) framework. In particular, given a specific dimension, we first enrich the source domain by introducing a domainness creator with providing additional supervisory signals. Guided by the created domainness, we design a self-adversarial regularizer and two loss functions to jointly disentangle the latent representations into domainness-specific and domainness-invariant features, thus mitigating the intra-domain gap. Our method can be easily taken as a plug-and-play framework and does not introduce any extra costs in the inference time. We achieve consistent improvements over state-of-the-art methods in both object detection and semantic segmentation.