尽管深度神经网络在各个领域中受到欢迎,但从机载激光扫描(ALS)点云中提取数字地形模型(DTM)仍然具有挑战性。这可能是由于缺乏专用的大规模注释数据集以及点云和DTMS之间的数据结构差异。为了促进数据驱动的DTM提取,本文从开源的ALS点云和相应的DTM中收集了带有各种城市,森林和山区场景的相应DTM。提出了一种基线方法,作为第一次尝试通过栅格化技术(即涂层的深层)从ALS点云中直接从ALS点云中提取数字地形模型的尝试。进行了良好的方法进行广泛的研究,以基准数据集对数据集进行基准测试,并分析学习从点云中提取DTM的挑战。实验结果显示了不可知论数据驱动的方法的兴趣,与为DTM提取设计的方法相比,次级误差级别。数据和源代码可在https://lhoangan.github.io/deepterra/上提供可重复性和进一步的类似研究。
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深度学习模型的最新发展,捕捉作物物候的复杂的时间模式有卫星图像时间序列(坐在),大大高级作物分类。然而,当施加到目标区域从训练区空间上不同的,这些模型差没有任何目标标签由于作物物候区域之间的时间位移进行。为了解决这个无人监督跨区域适应环境,现有方法学域不变特征没有任何目标的监督,而不是时间偏移本身。因此,这些技术提供了SITS只有有限的好处。在本文中,我们提出TimeMatch,一种新的无监督领域适应性方法SITS直接占时移。 TimeMatch由两个部分组成:1)时间位移的估计,其估计具有源极训练模型的未标记的目标区域的时间偏移,和2)TimeMatch学习,它结合了时间位移估计与半监督学习到一个分类适应未标记的目标区域。我们还引进了跨区域适应的开放式访问的数据集与来自欧洲四个不同区域的旁边。在此数据集,我们证明了TimeMatch优于所有竞争的方法,通过11%的在五个不同的适应情景F1-得分,创下了新的国家的最先进的跨区域适应性。
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Remote sensing satellites capture the cyclic dynamics of our Planet in regular time intervals recorded in satellite time series data. End-to-end trained deep learning models use this time series data to make predictions at a large scale, for instance, to produce up-to-date crop cover maps. Most time series classification approaches focus on the accuracy of predictions. However, the earliness of the prediction is also of great importance since coming to an early decision can make a crucial difference in time-sensitive applications. In this work, we present an End-to-End Learned Early Classification of Time Series (ELECTS) model that estimates a classification score and a probability of whether sufficient data has been observed to come to an early and still accurate decision. ELECTS is modular: any deep time series classification model can adopt the ELECTS conceptual idea by adding a second prediction head that outputs a probability of stopping the classification. The ELECTS loss function then optimizes the overall model on a balanced objective of earliness and accuracy. Our experiments on four crop classification datasets from Europe and Africa show that ELECTS allows reaching state-of-the-art accuracy while reducing the quantity of data massively to be downloaded, stored, and processed. The source code is available at https://github.com/marccoru/elects.
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Existing analyses of neural network training often operate under the unrealistic assumption of an extremely small learning rate. This lies in stark contrast to practical wisdom and empirical studies, such as the work of J. Cohen et al. (ICLR 2021), which exhibit startling new phenomena (the "edge of stability" or "unstable convergence") and potential benefits for generalization in the large learning rate regime. Despite a flurry of recent works on this topic, however, the latter effect is still poorly understood. In this paper, we take a step towards understanding genuinely non-convex training dynamics with large learning rates by performing a detailed analysis of gradient descent for simplified models of two-layer neural networks. For these models, we provably establish the edge of stability phenomenon and discover a sharp phase transition for the step size below which the neural network fails to learn "threshold-like" neurons (i.e., neurons with a non-zero first-layer bias). This elucidates one possible mechanism by which the edge of stability can in fact lead to better generalization, as threshold neurons are basic building blocks with useful inductive bias for many tasks.
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We introduce the XPER (eXplainable PERformance) methodology to measure the specific contribution of the input features to the predictive or economic performance of a model. Our methodology offers several advantages. First, it is both model-agnostic and performance metric-agnostic. Second, XPER is theoretically founded as it is based on Shapley values. Third, the interpretation of the benchmark, which is inherent in any Shapley value decomposition, is meaningful in our context. Fourth, XPER is not plagued by model specification error, as it does not require re-estimating the model. Fifth, it can be implemented either at the model level or at the individual level. In an application based on auto loans, we find that performance can be explained by a surprisingly small number of features. XPER decompositions are rather stable across metrics, yet some feature contributions switch sign across metrics. Our analysis also shows that explaining model forecasts and model performance are two distinct tasks.
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We introduce a parametric view of non-local two-step denoisers, for which BM3D is a major representative, where quadratic risk minimization is leveraged for unsupervised optimization. Within this paradigm, we propose to extend the underlying mathematical parametric formulation by iteration. This generalization can be expected to further improve the denoising performance, somehow curbed by the impracticality of repeating the second stage for all two-step denoisers. The resulting formulation involves estimating an even larger amount of parameters in a unsupervised manner which is all the more challenging. Focusing on the parameterized form of NL-Ridge, the simplest but also most efficient non-local two-step denoiser, we propose a progressive scheme to approximate the parameters minimizing the risk. In the end, the denoised images are made up of iterative linear combinations of patches. Experiments on artificially noisy images but also on real-world noisy images demonstrate that our method compares favorably with the very best unsupervised denoisers such as WNNM, outperforming the recent deep-learning-based approaches, while being much faster.
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The French National Institute of Geographical and Forest Information (IGN) has the mission to document and measure land-cover on French territory and provides referential geographical datasets, including high-resolution aerial images and topographic maps. The monitoring of land-cover plays a crucial role in land management and planning initiatives, which can have significant socio-economic and environmental impact. Together with remote sensing technologies, artificial intelligence (IA) promises to become a powerful tool in determining land-cover and its evolution. IGN is currently exploring the potential of IA in the production of high-resolution land cover maps. Notably, deep learning methods are employed to obtain a semantic segmentation of aerial images. However, territories as large as France imply heterogeneous contexts: variations in landscapes and image acquisition make it challenging to provide uniform, reliable and accurate results across all of France. The FLAIR-one dataset presented is part of the dataset currently used at IGN to establish the French national reference land cover map "Occupation du sol \`a grande \'echelle" (OCS- GE).
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Reflection high-energy electron diffraction (RHEED) is a powerful tool in molecular beam epitaxy (MBE), but RHEED images are often difficult to interpret, requiring experienced operators. We present an approach for automated surveillance of GaAs substrate deoxidation in MBE reactors using deep learning based RHEED image-sequence classification. Our approach consists of an non-supervised auto-encoder (AE) for feature extraction, combined with a supervised convolutional classifier network. We demonstrate that our lightweight network model can accurately identify the exact deoxidation moment. Furthermore we show that the approach is very robust and allows accurate deoxidation detection during months without requiring re-training. The main advantage of the approach is that it can be applied to raw RHEED images without requiring further information such as the rotation angle, temperature, etc.
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近年来,关于如何在公平限制下学习机器学习模型的越来越多的工作,通常在某些敏感属性方面表达。在这项工作中,我们考虑了对手对目标模型具有黑箱访问的设置,并表明对手可以利用有关该模型公平性的信息,以增强他对训练数据敏感属性的重建。更确切地说,我们提出了一种通用的重建校正方法,该方法将其作为对手进行的初始猜测,并纠正它以符合某些用户定义的约束(例如公平信息),同时最大程度地减少了对手猜测的变化。提出的方法对目标模型的类型,公平感知的学习方法以及对手的辅助知识不可知。为了评估我们的方法的适用性,我们对两种最先进的公平学习方法进行了彻底的实验评估,使用四个具有广泛公差的不同公平指标以及三个不同大小和敏感属性的数据集。实验结果证明了提出的方法改善训练集敏感属性的重建的有效性。
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为了减轻模型中不希望的偏差的影响,几种方法建议预先处理输入数据集,以通过防止敏感属性的推断来减少歧视风险。不幸的是,这些预处理方法中的大多数导致一代新分布与原始分布有很大不同,因此通常导致不切实际的数据。作为副作用,这种新的数据分布意味着需要重新训练现有模型才能做出准确的预测。为了解决这个问题,我们提出了一种新颖的预处理方法,我们将根据保护组的分布转换为所选目标一个,并具有附加的隐私约束,其目的是防止敏感敏感的推断属性。更确切地说,我们利用Wasserstein Gan和Attgan框架的最新作品来实现数据点的最佳运输以及强制保护属性推断的歧视器。我们提出的方法可以保留数据的可解释性,并且可以在不定义敏感组的情况下使用。此外,我们的方法可以专门建模现有的最新方法,从而提出对这些方法的统一观点。最后,关于真实和合成数据集的一些实验表明,我们的方法能够隐藏敏感属性,同时限制数据的变形并改善了后续数据分析任务的公平性。
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