在大型离散图形模型中，随机规划可以简化为概率推断，但是推理的硬度需要使用近似方案。在本文中，我们认为可以沿着两个维度解开此类应用程序。第一个是理想化的精确优化目标中的信息流的方向，即向后推理。第二个是用于计算该目标解决方案的近似类型，例如，信念传播（BP）与平均场变异推理（MFVI）。这种新的分类使我们能够在先前的工作中统一大量孤立的努力，以解释其联系和差异以及潜在的改进。对大型随机计划问题进行广泛的实验评估表明，BP比基于MFVI的几种算法的优势。对MFVI的实际局限性的分析激发了一种新型算法CSVI，该算法提供了更严格的变化近似，并通过正向BP实现了可比的计划性能。

The Position Embedding (PE) is critical for Vision Transformers (VTs) due to the permutation-invariance of self-attention operation. By analyzing the input and output of each encoder layer in VTs using reparameterization and visualization, we find that the default PE joining method (simply adding the PE and patch embedding together) operates the same affine transformation to token embedding and PE, which limits the expressiveness of PE and hence constrains the performance of VTs. To overcome this limitation, we propose a simple, effective, and robust method. Specifically, we provide two independent layer normalizations for token embeddings and PE for each layer, and add them together as the input of each layer's Muti-Head Self-Attention module. Since the method allows the model to adaptively adjust the information of PE for different layers, we name it as Layer-adaptive Position Embedding, abbreviated as LaPE. Extensive experiments demonstrate that LaPE can improve various VTs with different types of PE and make VTs robust to PE types. For example, LaPE improves 0.94% accuracy for ViT-Lite on Cifar10, 0.98% for CCT on Cifar100, and 1.72% for DeiT on ImageNet-1K, which is remarkable considering the negligible extra parameters, memory and computational cost brought by LaPE. The code is publicly available at https://github.com/Ingrid725/LaPE.

虽然视觉变压器（VT）体系结构在计算机视觉中越来越流行，但纯VT模型在微小的数据集上的性能较差。为了解决这个问题，本文提出了改善小型数据集VT性能的地方指南。我们首先分析，由于VTS中自我注意的机制的高灵活性和内在的全球性，因此很难用有限的数据来学习局部信息，这对于理解图像非常重要。为了促进本地信息，我们通过模仿已经训练有素的卷积神经网络（CNN）的特征来实现VT的当地指南，灵感来自CNN的内置本地到全球层次结构。在我们的双任务学习范式下，由低分辨率图像训练的轻型CNN提供的局部指导足以加速收敛并在很大程度上提高VT的性能。因此，我们的本地指导方法非常简单有效，可以作为小型数据集中VT的基本性能增强方法。广泛的实验表明，我们的方法在小型数据集中从头开始训练时可以显着改善VT，并且与不同种类的VT和数据集兼容。例如，我们提出的方法可以将各种VT在微型数据集上的性能提高（例如，DEIT 13.07％，T2T为8.98％，PVT为7.85％），并使更强大的基线PVTV2提高了1.86％至79.30％，显示出来小型数据集上的VT潜力。该代码可从https://github.com/lkhl/tiny-transformers获得。

在本文中，我们表明样品的欧几里得规范的差异可以在空间翻译和划分归一化之后对语义差异甚至混乱做出贡献。为了解决这个问题，我们提出了一种直观但有效的方法，以均衡样品向量的欧几里得规范。具体来说，我们$ l_2 $ - 在批准之前将每个样品向量归一化，因此样品向量的幅度相同。由于所提出的方法结合了$ L_2 $归一化和批量归一化，因此我们将我们的方法称为$ L_2 $ bn。 $ l_2 $ bn可以增强阶层内特征的紧凑性，并扩大阶层间特征的差异。此外，它可以帮助梯度收敛到稳定的量表。 $ l_2 $ bn易于实现，并且可以在没有任何其他参数和超参数的情况下发挥其效果。因此，它可以用作神经网络的基本归一化方法。我们通过对图像分类和声学场景分类任务进行各种模型的广泛实验来评估$ L_2 $亿美元的有效性。实验结果表明，$ L_2 $ bn能够提高各种神经网络模型的概括能力，并取得了可观的性能改进。

关节2D心脏分割和3D体积重建是建立统计心脏解剖模型的基础，并了解运动模式的功能机制。但是，由于CINE MR和高主体间方差的平面分辨率低，精确分割心脏图像并重建3D体积是具有挑战性的。在这项研究中，我们提出了一个基于潜在空间的端到端框架DeepRecon，该框架会产生多个临床上基本的结果，包括准确的图像分割，合成高分辨率3D图像和3D重建体积。我们的方法确定了Cine图像的最佳潜在表示，其中包含心脏结构的准确语义信息。特别是，我们的模型共同生成具有准确的语义信息的合成图像，并使用最佳潜在表示对心脏结构进行分割。我们进一步探索了3D形状重建和4D运动模式通过不同的潜在空间操纵策略进行适应的下游应用。同时生成的高分辨率图像具有评估心脏形状和运动的高可解释价值。实验性结果证明了我们的有效性在多个方面的方法，包括2D分割，3D重建，下游4D运动模式适应性。

组合来自多视图图像的信息对于提高自动化方法的疾病诊断方法的性能和鲁棒性至关重要。但是，由于多视图图像的非对齐特性，跨视图的构建相关性和数据融合在很大程度上仍然是一个开放的问题。在这项研究中，我们提出了输血，这是一种基于变压器的体系结构，可使用卷积层和强大的注意机制合并不同的多视图成像信息。特别是，针对丰富的跨视图上下文建模和语义依赖性挖掘，提出了发散的融合注意（DIFA）模块，以解决从不同图像视图中捕获未对齐数据之间的长期相关性的关键问题。我们进一步提出了多尺度注意（MSA），以收集多尺度特征表示的全局对应关系。我们评估了心脏MRI（M \＆MS-2）挑战队列中多疾病，多视图\＆多中心右心室分段的输血。输血表明了针对最先进方法的领先绩效，并为多视图成像集成的新观点打开了稳健的医学图像分割。

作为新一代神经体系结构的变形金刚在自然语言处理和计算机视觉方面表现出色。但是，现有的视觉变形金刚努力使用有限的医学数据学习，并且无法概括各种医学图像任务。为了应对这些挑战，我们将Medformer作为数据量表变压器呈现为可推广的医学图像分割。关键设计结合了理想的电感偏差，线性复杂性的层次建模以及以空间和语义全局方式以线性复杂性的关注以及多尺度特征融合。 Medformer可以在不预训练的情况下学习微小至大规模的数据。广泛的实验表明，Medformer作为一般分割主链的潜力，在三个具有多种模式（例如CT和MRI）和多样化的医学靶标（例如，健康器官，疾病，疾病组织和肿瘤）的三个公共数据集上优于CNN和视觉变压器。我们将模型和评估管道公开可用，为促进广泛的下游临床应用提供固体基线和无偏比较。

A recent study has shown a phenomenon called neural collapse in that the within-class means of features and the classifier weight vectors converge to the vertices of a simplex equiangular tight frame at the terminal phase of training for classification. In this paper, we explore the corresponding structures of the last-layer feature centers and classifiers in semantic segmentation. Based on our empirical and theoretical analysis, we point out that semantic segmentation naturally brings contextual correlation and imbalanced distribution among classes, which breaks the equiangular and maximally separated structure of neural collapse for both feature centers and classifiers. However, such a symmetric structure is beneficial to discrimination for the minor classes. To preserve these advantages, we introduce a regularizer on feature centers to encourage the network to learn features closer to the appealing structure in imbalanced semantic segmentation. Experimental results show that our method can bring significant improvements on both 2D and 3D semantic segmentation benchmarks. Moreover, our method ranks 1st and sets a new record (+6.8% mIoU) on the ScanNet200 test leaderboard. Code will be available at https://github.com/dvlab-research/Imbalanced-Learning.

Weakly-supervised object localization aims to indicate the category as well as the scope of an object in an image given only the image-level labels. Most of the existing works are based on Class Activation Mapping (CAM) and endeavor to enlarge the discriminative area inside the activation map to perceive the whole object, yet ignore the co-occurrence confounder of the object and context (e.g., fish and water), which makes the model inspection hard to distinguish object boundaries. Besides, the use of CAM also brings a dilemma problem that the classification and localization always suffer from a performance gap and can not reach their highest accuracy simultaneously. In this paper, we propose a casual knowledge distillation method, dubbed KD-CI-CAM, to address these two under-explored issues in one go. More specifically, we tackle the co-occurrence context confounder problem via causal intervention (CI), which explores the causalities among image features, contexts, and categories to eliminate the biased object-context entanglement in the class activation maps. Based on the de-biased object feature, we additionally propose a multi-teacher causal distillation framework to balance the absorption of classification knowledge and localization knowledge during model training. Extensive experiments on several benchmarks demonstrate the effectiveness of KD-CI-CAM in learning clear object boundaries from confounding contexts and addressing the dilemma problem between classification and localization performance.

Witnessing the impressive achievements of pre-training techniques on large-scale data in the field of computer vision and natural language processing, we wonder whether this idea could be adapted in a grab-and-go spirit, and mitigate the sample inefficiency problem for visuomotor driving. Given the highly dynamic and variant nature of the input, the visuomotor driving task inherently lacks view and translation invariance, and the visual input contains massive irrelevant information for decision making, resulting in predominant pre-training approaches from general vision less suitable for the autonomous driving task. To this end, we propose PPGeo (Policy Pre-training via Geometric modeling), an intuitive and straightforward fully self-supervised framework curated for the policy pretraining in visuomotor driving. We aim at learning policy representations as a powerful abstraction by modeling 3D geometric scenes on large-scale unlabeled and uncalibrated YouTube driving videos. The proposed PPGeo is performed in two stages to support effective self-supervised training. In the first stage, the geometric modeling framework generates pose and depth predictions simultaneously, with two consecutive frames as input. In the second stage, the visual encoder learns driving policy representation by predicting the future ego-motion and optimizing with the photometric error based on current visual observation only. As such, the pre-trained visual encoder is equipped with rich driving policy related representations and thereby competent for multiple visuomotor driving tasks. Extensive experiments covering a wide span of challenging scenarios have demonstrated the superiority of our proposed approach, where improvements range from 2% to even over 100% with very limited data. Code and models will be available at https://github.com/OpenDriveLab/PPGeo.