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.

域的适应区域对解决许多应用程序遇到的域移位问题发挥了重要作用。由于与现实测试方案中使用的目标数据相比，用于培训的源数据的分布之间的差异是由于培训源数据之间的差异而产生的。在本文中，我们引入了一种新型的多尺度域自适应Yolo（MS-Dayolo）框架，该框架在最近引入的Yolov4对象检测器的不同尺度上采用了多个域自适应路径和相应的域分类器。在我们的基线多尺度Dayolo框架的基础上，我们为域名适应网络（DAN）介绍了三个新颖的深度学习体系结构，它们生成了域，不变性功能。特别是，我们提出了渐进式功能减少（PFR），统一分类器（UC）和集成体系结构。我们使用流行的数据集训练和测试我们提出的DAN体系结构。当使用拟议的MS-Dayolo架构训练Yolov4时，我们的实验显示了对象检测性能的显着改善，并在对目标数据进行自动驾驶应用程序中进行测试时。此外，MS-Dayolo框架相对于更快的R-CNN解决方案，在提供可比的对象检测性能的同时，实现了实时速度的数量级改进。

在各种计算机视觉任务（例如对象检测，实例分段等）中，无监督的域适应至关重要。他们试图减少域偏差诱导的性能下降，同时还促进模型应用速度。域适应对象检测中的先前作品尝试使图像级和实例级别变化对准以最大程度地减少域差异，但是它们可能会使单级功能与图像级域适应中的混合级功能相结合，因为对象中的每个图像中的每个图像检测任务可能不止一个类和对象。为了通过单级对齐获得单级和混合级对齐方式，我们将功能的混合级视为新班级，并建议使用混合级$ h-divergence $，以供对象检测到实现均匀特征对准并减少负转移。然后，还提出了基于混合级$ h-Divergence $的语义一致性特征对齐模型（SCFAM）。为了改善单层和混合级的语义信息并完成语义分离，SCFAM模型提出了语义预测模型（SPM）和语义桥接组件（SBC）。然后根据SPM结果更改PIX域鉴别器损耗的重量，以减少样品不平衡。广泛使用的数据集上的广泛无监督域的适应实验说明了我们所提出的方法在域偏置设置中的强大对象检测。

对象检测的域适应性（DAOD）最近由于其检测目标对象而没有任何注释而引起了很多关注。为了解决该问题，以前的作品着重于通过对抗训练在两阶段检测器中从部分级别（例如图像级，实例级，RPN级）提取的对齐功能。但是，对象检测管道中的个体级别相互密切相关，并且尚未考虑此层次之间的关系。为此，我们为DAOD介绍了一个新的框架，该框架具有三个提出的组件：多尺度意识不确定性注意力（MUA），可转移的区域建议网络（TRPN）和动态实例采样（DIS）。使用这些模块，我们试图在训练过程中减少负转移效应，同时最大化可传递性以及两个领域的可区分性。最后，我们的框架隐含地学习了域不变区域，以通过利用可转移信息并通过协作利用其域信息来增强不同检测级别之间的互补性。通过消融研究和实验，我们表明所提出的模块以协同方式有助于性能提高，以证明我们方法的有效性。此外，我们的模型在各种基准测试方面达到了新的最新性能。

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.

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.

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}.

通用域自适应对象检测（UNIDAOD）比域自适应对象检测（DAOD）更具挑战性，因为源域的标签空间可能与目标的标签空间不相同，并且在通用场景中的对象的比例可能会大大变化（即，类别转移和比例位移）。为此，我们提出了US-DAF，即使用多标签学习的US-DAF，即具有多个标记的rcnn自适应率更快，以减少训练期间的负转移效应，同时最大化可传递性以及在各种规模下两个领域的可区分性。具体而言，我们的方法由两个模块实现：1）我们通过设计滤波器机制模块来克服类别移动引起的负转移来促进普通类的特征对齐，并抑制私人类的干扰。 2）我们通过引入一个新的多标签尺度感知适配器来在对象检测中填充比例感知适应的空白，以在两个域的相应刻度之间执行单个对齐。实验表明，US-DAF在三种情况下（即开放式，部分集和封闭设置）实现最新结果，并在基准数据集clipart1k和水彩方面的相对改善中获得7.1％和5.9％的相对改善。特定。

我们建议利用模拟的潜力，以域的概括方式对现实世界自动驾驶场景的语义分割。对分割网络进行了训练，没有任何目标域数据，并在看不见的目标域进行了测试。为此，我们提出了一种新的域随机化和金字塔一致性的方法，以学习具有高推广性的模型。首先，我们建议使用辅助数据集以视觉外观的方式随机将合成图像随机化，以有效地学习域不变表示。其次，我们进一步在不同的“风格化”图像和图像中实施了金字塔一致性，以分别学习域不变和规模不变的特征。关于从GTA和合成对城市景观，BDD和Mapillary的概括进行了广泛的实验；而我们的方法比最新技术取得了卓越的成果。值得注意的是，我们的概括结果与最先进的模拟域适应方法相比甚至更好，甚至比在训练时访问目标域数据的结果。

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％）

无监督域适应（UDA）技术的最新进展在跨域计算机视觉任务中有巨大的成功，通过弥合域分布差距来增强数据驱动的深度学习架构的泛化能力。对于基于UDA的跨域对象检测方法，其中大多数通过对抗性学习策略引导域不变特征产生来缓解域偏差。然而，由于不稳定的对抗性培训过程，他们的域名鉴别器具有有限的分类能力。因此，它们引起的提取特征不能完全域不变，仍然包含域私有因素，使障碍物进一步缓解跨域差异。为了解决这个问题，我们设计一个域分离rcnn（DDF），以消除特定于检测任务学习的特定信息。我们的DDF方法促进了全局和本地阶段的功能解剖，分别具有全局三联脱离（GTD）模块和实例相似性解剖（ISD）模块。通过在四个基准UDA对象检测任务上表现出最先进的方法，对我们的DDF方法进行了宽阔的适用性。

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.

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。

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。

Semantic segmentation is a key problem for many computer vision tasks. While approaches based on convolutional neural networks constantly break new records on different benchmarks, generalizing well to diverse testing environments remains a major challenge. In numerous real world applications, there is indeed a large gap between data distributions in train and test domains, which results in severe performance loss at run-time. In this work, we address the task of unsupervised domain adaptation in semantic segmentation with losses based on the entropy of the pixel-wise predictions. To this end, we propose two novel, complementary methods using (i) an entropy loss and (ii) an adversarial loss respectively. We demonstrate state-of-theart performance in semantic segmentation on two challenging "synthetic-2-real" set-ups 1 and show that the approach can also be used for detection.

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。

检测变压器最近显示出有希望的对象检测结果，并引起了越来越多的注意力。但是，如何开发有效的域适应技术来改善其跨域性能，尚不清楚和不清楚。在本文中，我们深入研究了这个主题，并从经验上发现，CNN骨架上的直接特征分布对齐仅带来有限的改进，因为它不能保证变压器中的域不变序列特征进行预测。为了解决这个问题，我们提出了一种新型的序列特征比对（SFA）方法，该方法是专门设计用于适应检测变压器的。从技术上讲，SFA由基于域查询的特征对齐（DQFA）模块和令牌特征对齐（TDA）模块组成。在DQFA中，一个新的域查询用于从两个域的令牌序列中汇总和对齐全局上下文。 DQFA分别在变压器编码器和解码器中部署时，降低了全局特征表示和对象关系中的域差异。同时，TDA在两个域中的序列中都对准令牌特征，从而分别降低了变压器编码器和解码器中局部和实例级特征表示中的域间隙。此外，提出了一种新型的两分匹配损失，以增强可鲁棒对象检测的特征可区分性。在三个具有挑战性的基准上进行的实验表明，SFA优于最先进的域自适应对象检测方法。代码已在以下网址提供：https：//github.com/encounter1997/sfa。

DETR风格的检测器在内域场景中脱颖而出，但是它们在域移位设置中的属性却没有探索。本文旨在根据两个发现，在域移位设置上使用DETR式检测器建立一个简单但有效的基线。首先，减轻主链的域移动，解码器输出功能在获得有利的结果方面表现出色。对于另一种高级域对准方法，这两个部分都进一步增强了性能。因此，我们提出了对象感知的对准（OAA）模块和最佳基于运输的比对（OTA）模块，以在骨干和检测器的输出上实现全面的域对齐。 OAA模块将伪标签标识的前景区域对齐骨干输出中的伪标签，从而导致基于域的不变特征。 OTA模块利用切成薄片的Wasserstein距离来最大化位置信息的保留，同时最大程度地减少解码器输出中的域间隙。我们将调查结果和对齐模块实施到我们的适应方法中，并基准在域移位设置上基于DETR风格的检测器。在各种领域自适应场景上进行的实验验证了我们方法的有效性。

We consider the problem of unsupervised domain adaptation in semantic segmentation. A key in this campaign consists in reducing the domain shift, i.e., enforcing the data distributions of the two domains to be similar. One of the common strategies is to align the marginal distribution in the feature space through adversarial learning. However, this global alignment strategy does not consider the category-level joint distribution. A possible consequence of such global movement is that some categories which are originally well aligned between the source and target may be incorrectly mapped, thus leading to worse segmentation results in target domain. To address this problem, we introduce a category-level adversarial network, aiming to enforce local semantic consistency during the trend of global alignment. Our idea is to take a close look at the category-level joint distribution and align each class with an adaptive adversarial loss. Specifically, we reduce the weight of the adversarial loss for category-level aligned features while increasing the adversarial force for those poorly aligned. In this process, we decide how well a feature is category-level aligned between source and target by a co-training approach. In two domain adaptation tasks, i.e., GTA5 → Cityscapes and SYN-THIA → Cityscapes, we validate that the proposed method matches the state of the art in segmentation accuracy.

Convolutional neural network-based approaches for semantic segmentation rely on supervision with pixel-level ground truth, but may not generalize well to unseen image domains. As the labeling process is tedious and labor intensive, developing algorithms that can adapt source ground truth labels to the target domain is of great interest. In this paper, we propose an adversarial learning method for domain adaptation in the context of semantic segmentation. Considering semantic segmentations as structured outputs that contain spatial similarities between the source and target domains, we adopt adversarial learning in the output space. To further enhance the adapted model, we construct a multi-level adversarial network to effectively perform output space domain adaptation at different feature levels. Extensive experiments and ablation study are conducted under various domain adaptation settings, including synthetic-to-real and cross-city scenarios. We show that the proposed method performs favorably against the stateof-the-art methods in terms of accuracy and visual quality.