Existing 3D-aware image synthesis approaches mainly focus on generating a single canonical object and show limited capacity in composing a complex scene containing a variety of objects. This work presents DisCoScene: a 3Daware generative model for high-quality and controllable scene synthesis. The key ingredient of our method is a very abstract object-level representation (i.e., 3D bounding boxes without semantic annotation) as the scene layout prior, which is simple to obtain, general to describe various scene contents, and yet informative to disentangle objects and background. Moreover, it serves as an intuitive user control for scene editing. Based on such a prior, the proposed model spatially disentangles the whole scene into object-centric generative radiance fields by learning on only 2D images with the global-local discrimination. Our model obtains the generation fidelity and editing flexibility of individual objects while being able to efficiently compose objects and the background into a complete scene. We demonstrate state-of-the-art performance on many scene datasets, including the challenging Waymo outdoor dataset. Project page: https://snap-research.github.io/discoscene/
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生成建模的最新趋势是从2D图像收集中构建3D感知发电机。为了诱导3D偏见,此类模型通常依赖于体积渲染,这在高分辨率下使用昂贵。在过去的几个月中,似乎有10幅以上的作品通过训练单独的2D解码器来修饰由纯3D发电机产生的低分辨率图像(或功能张量)来解决这个扩展问题。但是该解决方案是有代价的:它不仅打破了多视图的一致性(即相机移动时的形状和纹理变化),而且还以低忠诚度学习了几何形状。在这项工作中,我们表明可以通过遵循完全不同的途径,简单地训练模型贴片,以获得具有SOTA图像质量的高分辨率3D发电机。我们通过两种方式重新审视和改进此优化方案。首先,我们设计了一个位置和比例意识的歧视器来处理不同比例和空间位置的贴片。其次,我们基于退火beta分布来修改补丁采样策略,以稳定训练并加速收敛。所得的模型名为Epigraf,是一个高效,高分辨率的纯3D发电机,我们在四个数据集(在这项工作中引入两个)上测试了它,价格为$ 256^2 $和$ 512^2 $分辨率。它获得了最先进的图像质量,高保真的几何形状,并比基于UpSampler的同行训练$ {\ oft} 2.5 \ times $ $。项目网站:https://universome.github.io/epigraf。
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神经渲染可用于在没有3D监督的情况下重建形状的隐式表示。然而,当前的神经表面重建方法难以学习形状的高频细节,因此经常过度厚度地呈现重建形状。我们提出了一种新的方法来提高神经渲染中表面重建的质量。我们遵循最近的工作,将表面模型为签名的距离字段。首先,我们提供了一个派生,以分析签名的距离函数,体积密度,透明度函数和体积渲染方程中使用的加权函数之间的关系。其次,我们观察到,试图在单个签名的距离函数中共同编码高频和低频组件会导致不稳定的优化。我们建议在基本函数和位移函数中分解签名的距离函数以及粗到最新的策略,以逐渐增加高频细节。最后,我们建议使用一种自适应策略,使优化能够专注于改善签名距离场具有伪影的表面附近的某些区域。我们的定性和定量结果表明,我们的方法可以重建高频表面细节,并获得比目前的现状更好的表面重建质量。代码将在https://github.com/yiqun-wang/hfs上发布。
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视频显示连续事件,但大多数 - 如果不是全部 - 视频综合框架及时酌情对待它们。在这项工作中,我们想到它们应该是连续的信号的视频,并扩展神经表示的范式以构建连续时间视频发生器。为此,我们首先通过位置嵌入的镜头设计连续运动表示。然后,我们探讨了在非常稀疏的视频上培训问题,并证明可以使用每剪辑的少数为2帧来学习良好的发电机。之后,我们重新思考传统的图像和视频鉴别器对并建议使用基于Hypernetwork的一个。这降低了培训成本并向发电机提供了更丰富的学习信号,使得可以首次直接培训1024美元$ ^ 2 $视频。我们在Stylegan2的顶部构建我们的模型,并且在同样的分辨率下培训速度速度较高5%,同时实现几乎相同的图像质量。此外,我们的潜在空间具有类似的属性,使我们的方法可以及时传播的空间操纵。我们可以在任意高帧速率下任意长的视频,而现有工作努力以固定速率生成均匀的64个帧。我们的模型在四个现代256美元$ ^ 2 $视频综合基准测试中实现最先进的结果,一个1024美元$ ^ 2 $ state。视频和源代码在项目网站上提供:https://universome.github.io/stylegan-v。
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Machine learning models are typically evaluated by computing similarity with reference annotations and trained by maximizing similarity with such. Especially in the bio-medical domain, annotations are subjective and suffer from low inter- and intra-rater reliability. Since annotations only reflect the annotation entity's interpretation of the real world, this can lead to sub-optimal predictions even though the model achieves high similarity scores. Here, the theoretical concept of Peak Ground Truth (PGT) is introduced. PGT marks the point beyond which an increase in similarity with the reference annotation stops translating to better Real World Model Performance (RWMP). Additionally, a quantitative technique to approximate PGT by computing inter- and intra-rater reliability is proposed. Finally, three categories of PGT-aware strategies to evaluate and improve model performance are reviewed.
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A "heart attack" or myocardial infarction (MI), occurs when an artery supplying blood to the heart is abruptly occluded. The "gold standard" method for imaging MI is Cardiovascular Magnetic Resonance Imaging (MRI), with intravenously administered gadolinium-based contrast (late gadolinium enhancement). However, no "gold standard" fully automated method for the quantification of MI exists. In this work, we propose an end-to-end fully automatic system (MyI-Net) for the detection and quantification of MI in MRI images. This has the potential to reduce the uncertainty due to the technical variability across labs and inherent problems of the data and labels. Our system consists of four processing stages designed to maintain the flow of information across scales. First, features from raw MRI images are generated using feature extractors built on ResNet and MoblieNet architectures. This is followed by the Atrous Spatial Pyramid Pooling (ASPP) to produce spatial information at different scales to preserve more image context. High-level features from ASPP and initial low-level features are concatenated at the third stage and then passed to the fourth stage where spatial information is recovered via up-sampling to produce final image segmentation output into: i) background, ii) heart muscle, iii) blood and iv) scar areas. New models were compared with state-of-art models and manual quantification. Our models showed favorable performance in global segmentation and scar tissue detection relative to state-of-the-art work, including a four-fold better performance in matching scar pixels to contours produced by clinicians.
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Graph neural networks (GNN) have become the default machine learning model for relational datasets, including protein interaction networks, biological neural networks, and scientific collaboration graphs. We use tools from statistical physics and random matrix theory to precisely characterize generalization in simple graph convolution networks on the contextual stochastic block model. The derived curves are phenomenologically rich: they explain the distinction between learning on homophilic and heterophilic graphs and they predict double descent whose existence in GNNs has been questioned by recent work. Our results are the first to accurately explain the behavior not only of a stylized graph learning model but also of complex GNNs on messy real-world datasets. To wit, we use our analytic insights about homophily and heterophily to improve performance of state-of-the-art graph neural networks on several heterophilic benchmarks by a simple addition of negative self-loop filters.
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In this paper, we propose a new neural network architecture based on the H2 matrix. Even though networks with H2-inspired architecture already exist, and our approach is designed to reduce memory costs and improve performance by taking into account the sparsity template of the H2 matrix. In numerical comparison with alternative neural networks, including the known H2-based ones, our architecture showed itself as beneficial in terms of performance, memory, and scalability.
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Semi-supervised learning (SSL) has made significant strides in the field of remote sensing. Finding a large number of labeled datasets for SSL methods is uncommon, and manually labeling datasets is expensive and time-consuming. Furthermore, accurately identifying remote sensing satellite images is more complicated than it is for conventional images. Class-imbalanced datasets are another prevalent phenomenon, and models trained on these become biased towards the majority classes. This becomes a critical issue with an SSL model's subpar performance. We aim to address the issue of labeling unlabeled data and also solve the model bias problem due to imbalanced datasets while achieving better accuracy. To accomplish this, we create "artificial" labels and train a model to have reasonable accuracy. We iteratively redistribute the classes through resampling using a distribution alignment technique. We use a variety of class imbalanced satellite image datasets: EuroSAT, UCM, and WHU-RS19. On UCM balanced dataset, our method outperforms previous methods MSMatch and FixMatch by 1.21% and 0.6%, respectively. For imbalanced EuroSAT, our method outperforms MSMatch and FixMatch by 1.08% and 1%, respectively. Our approach significantly lessens the requirement for labeled data, consistently outperforms alternative approaches, and resolves the issue of model bias caused by class imbalance in datasets.
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Fine-tuning a Pre-trained Language Model (PLM) on a specific downstream task has been a well-known paradigm in Natural Language Processing. However, with the ever-growing size of PLMs, training the entire model on several downstream tasks becomes very expensive and resource-hungry. Recently, different Parameter Efficient Tuning (PET) techniques are proposed to improve the efficiency of fine-tuning PLMs. One popular category of PET methods is the low-rank adaptation methods which insert learnable truncated SVD modules into the original model either sequentially or in parallel. However, low-rank decomposition suffers from limited representation power. In this work, we address this problem using the Kronecker product instead of the low-rank representation. We introduce KronA, a Kronecker product-based adapter module for efficient fine-tuning of Transformer-based PLMs. We apply the proposed methods for fine-tuning T5 on the GLUE benchmark to show that incorporating the Kronecker-based modules can outperform state-of-the-art PET methods.
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