减少斑点并限制合成孔径雷达(SAR)图像中物理参数的变化通常是完全利用此类数据潜力的关键步骤。如今,深度学习方法产生了最新的现状,从而导致单位SAR修复。然而,现在经常可用巨大的多阶梯堆栈,并且可以有效利用以进一步提高图像质量。本文探讨了两种快速的策略,这些策略采用单像伪装算法,即SAR2SAR,在多个阶段的框架中。第一个是基于Quegan过滤器,并取代了SAR2SAR的局部反射率预估计。第二个使用SAR2SAR来抑制从“超级图像”的形式(即时间序列的时间算术平均值)形式的形式编码多个时间段信息的比率图像中抑制斑点。 Sentinel-1 GRD数据的实验结果表明,这两种多时间策略提供了改进的过滤结果,同时增加了有限的计算成本。
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斑点过滤通常是分析合成孔径雷达(SAR)图像的先决条件。在单像伪装的领域取得了巨大进步。最新技术依靠深度神经网络来恢复SAR图像特有的各种结构和纹理。 SAR图像的时间序列的可用性提供了通过在同一区域结合不同斑点实现来改善斑点过滤的可能性。深度神经网络的监督培训需要无基真斑点图像。这样的图像只能通过某种平均形式,空间或时间整合间接获得,并且不完美。考虑到通过多阶段斑点滤波可以达到非常高质量的恢复的潜力,需要规避地面真相图像的局限性。我们将最新的自我监督训练策略扩展到了称为Merlin的单外观复杂SAR图像的情况,以进行多个颞滤波。这需要对空间和时间维度以及复杂幅度的真实组件和虚构组件之间的统计依赖性来源进行建模。使用模拟斑点上的数据集进行定量分析表明,当包括其他SAR图像时,斑点减少了明显改善。然后,将我们的方法应用于Terrasar-X图像的堆栈,并显示出优于竞争的多阶段斑点滤波方法。在$ \ href {https://gitlab.telecom-paris.fr/ring/multi-temporal-merlin/} {\ text {gitlab}} $上LTCI实验室,T \'El \'Ecom Paris Institut Polytechnique de Paris。
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斑点波动严重限制了合成孔径雷达(SAR)图像的可解释性。因此,散斑减少是跨越至少四十年的众多作品的主题。基于深度神经网络的技术最近在SAR图像恢复质量方面实现了一种新的性能。超出了合适的网络架构的设计或选择足够的损失功能,培训集的构建是最重要的。到目前为止,大多数方法都考虑了监督培训策略:培训网络以产生尽可能靠近斑点的参考图像的输出。无斑点图像通常不可用,这需要采用自然或光学图像或在长时间序列中选择稳定区域,以规避缺乏地面真理。另一方面,自我监督避免使用无斑点图像。我们介绍了一个自我监督的战略,基于单眼复杂的SAR图像的真实和虚构部分的分离,称为Merlin(复杂的自我监督的机除),并表明它提供了一种培训各种深度掠夺的直接途径网络。由于特定于给定传感器和成像模式的SAR传输功能,使用Merlin培训的网络考虑了空间相关性。通过只需要一个图像,并且可能利用大型档案,Merlin将门打开了无忧无虑的机器,以及对机器网络的大规模培训。培训型号的代码是在https://gitlab.telecom-paris.fr/ring/mollin的。
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Self-supervised learning is a popular and powerful method for utilizing large amounts of unlabeled data, for which a wide variety of training objectives have been proposed in the literature. In this study, we perform a Bayesian analysis of state-of-the-art self-supervised learning objectives and propose a unified formulation based on likelihood learning. Our analysis suggests a simple method for integrating self-supervised learning with generative models, allowing for the joint training of these two seemingly distinct approaches. We refer to this combined framework as GEDI, which stands for GEnerative and DIscriminative training. Additionally, we demonstrate an instantiation of the GEDI framework by integrating an energy-based model with a cluster-based self-supervised learning model. Through experiments on synthetic and real-world data, including SVHN, CIFAR10, and CIFAR100, we show that GEDI outperforms existing self-supervised learning strategies in terms of clustering performance by a wide margin. We also demonstrate that GEDI can be integrated into a neural-symbolic framework to address tasks in the small data regime, where it can use logical constraints to further improve clustering and classification performance.
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We propose a novel approach for deep learning-based Multi-View Stereo (MVS). For each pixel in the reference image, our method leverages a deep architecture to search for the corresponding point in the source image directly along the corresponding epipolar line. We denote our method DELS-MVS: Deep Epipolar Line Search Multi-View Stereo. Previous works in deep MVS select a range of interest within the depth space, discretize it, and sample the epipolar line according to the resulting depth values: this can result in an uneven scanning of the epipolar line, hence of the image space. Instead, our method works directly on the epipolar line: this guarantees an even scanning of the image space and avoids both the need to select a depth range of interest, which is often not known a priori and can vary dramatically from scene to scene, and the need for a suitable discretization of the depth space. In fact, our search is iterative, which avoids the building of a cost volume, costly both to store and to process. Finally, our method performs a robust geometry-aware fusion of the estimated depth maps, leveraging a confidence predicted alongside each depth. We test DELS-MVS on the ETH3D, Tanks and Temples and DTU benchmarks and achieve competitive results with respect to state-of-the-art approaches.
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Timely and effective feedback within surgical training plays a critical role in developing the skills required to perform safe and efficient surgery. Feedback from expert surgeons, while especially valuable in this regard, is challenging to acquire due to their typically busy schedules, and may be subject to biases. Formal assessment procedures like OSATS and GEARS attempt to provide objective measures of skill, but remain time-consuming. With advances in machine learning there is an opportunity for fast and objective automated feedback on technical skills. The SimSurgSkill 2021 challenge (hosted as a sub-challenge of EndoVis at MICCAI 2021) aimed to promote and foster work in this endeavor. Using virtual reality (VR) surgical tasks, competitors were tasked with localizing instruments and predicting surgical skill. Here we summarize the winning approaches and how they performed. Using this publicly available dataset and results as a springboard, future work may enable more efficient training of surgeons with advances in surgical data science. The dataset can be accessed from https://console.cloud.google.com/storage/browser/isi-simsurgskill-2021.
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A tractogram is a virtual representation of the brain white matter. It is composed of millions of virtual fibers, encoded as 3D polylines, which approximate the white matter axonal pathways. To date, tractograms are the most accurate white matter representation and thus are used for tasks like presurgical planning and investigations of neuroplasticity, brain disorders, or brain networks. However, it is a well-known issue that a large portion of tractogram fibers is not anatomically plausible and can be considered artifacts of the tracking procedure. With Verifyber, we tackle the problem of filtering out such non-plausible fibers using a novel fully-supervised learning approach. Differently from other approaches based on signal reconstruction and/or brain topology regularization, we guide our method with the existing anatomical knowledge of the white matter. Using tractograms annotated according to anatomical principles, we train our model, Verifyber, to classify fibers as either anatomically plausible or non-plausible. The proposed Verifyber model is an original Geometric Deep Learning method that can deal with variable size fibers, while being invariant to fiber orientation. Our model considers each fiber as a graph of points, and by learning features of the edges between consecutive points via the proposed sequence Edge Convolution, it can capture the underlying anatomical properties. The output filtering results highly accurate and robust across an extensive set of experiments, and fast; with a 12GB GPU, filtering a tractogram of 1M fibers requires less than a minute. Verifyber implementation and trained models are available at https://github.com/FBK-NILab/verifyber.
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Semi-supervised learning methods can train high-accuracy machine learning models with a fraction of the labeled training samples required for traditional supervised learning. Such methods do not typically involve close review of the unlabeled training samples, making them tempting targets for data poisoning attacks. In this paper we investigate the vulnerabilities of semi-supervised learning methods to backdoor data poisoning attacks on the unlabeled samples. We show that simple poisoning attacks that influence the distribution of the poisoned samples' predicted labels are highly effective - achieving an average attack success rate as high as 96.9%. We introduce a generalized attack framework targeting semi-supervised learning methods to better understand and exploit their limitations and to motivate future defense strategies.
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Extreme wildfires continue to be a significant cause of human death and biodiversity destruction within countries that encompass the Mediterranean Basin. Recent worrying trends in wildfire activity (i.e., occurrence and spread) suggest that wildfires are likely to be highly impacted by climate change. In order to facilitate appropriate risk mitigation, it is imperative to identify the main drivers of extreme wildfires and assess their spatio-temporal trends, with a view to understanding the impacts of global warming on fire activity. To this end, we analyse the monthly burnt area due to wildfires over a region encompassing most of Europe and the Mediterranean Basin from 2001 to 2020, and identify high fire activity during this period in eastern Europe, Algeria, Italy and Portugal. We build an extreme quantile regression model with a high-dimensional predictor set describing meteorological conditions, land cover usage, and orography, for the domain. To model the complex relationships between the predictor variables and wildfires, we make use of a hybrid statistical deep-learning framework that allows us to disentangle the effects of vapour-pressure deficit (VPD), air temperature, and drought on wildfire activity. Our results highlight that whilst VPD, air temperature, and drought significantly affect wildfire occurrence, only VPD affects extreme wildfire spread. Furthermore, to gain insights into the effect of climate change on wildfire activity in the near future, we perturb VPD and temperature according to their observed trends and find evidence that global warming may lead to spatially non-uniform changes in wildfire activity.
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Recent video+language datasets cover domains where the interaction is highly structured, such as instructional videos, or where the interaction is scripted, such as TV shows. Both of these properties can lead to spurious cues to be exploited by models rather than learning to ground language. In this paper, we present GrOunded footbAlL commentaries (GOAL), a novel dataset of football (or `soccer') highlights videos with transcribed live commentaries in English. As the course of a game is unpredictable, so are commentaries, which makes them a unique resource to investigate dynamic language grounding. We also provide state-of-the-art baselines for the following tasks: frame reordering, moment retrieval, live commentary retrieval and play-by-play live commentary generation. Results show that SOTA models perform reasonably well in most tasks. We discuss the implications of these results and suggest new tasks for which GOAL can be used. Our codebase is available at: https://gitlab.com/grounded-sport-convai/goal-baselines.
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