突出对象检测在许多下游任务中发挥着重要作用。然而,复杂的现实世界场景具有不同尺度和突出对象的数量仍然构成挑战。在本文中,我们直接解决了在复杂场景中检测多个突出对象的问题。我们提出了一种在空间和频道空间中的非本地特征信息的网络架构,捕获单独对象之间的远程依赖性。传统的自下而上和非本地特征与特征融合门中的边缘特性相结合,逐渐改进解码器中的突出物体预测。我们表明,即使在复杂的情况下,我们的方法也可以准确地定位多个突出区域。为了证明我们对多个突出对象问题的方法的功效,我们策划仅包含多个突出对象的新数据集。我们的实验证明了所提出的方法在没有任何预处理和后处理的情况下展示了五种广泛使用的数据集的最新结果。我们在我们的多对象数据集中获得了对竞争技术的进一步绩效改进。数据集和源代码是可用的:https://github.com/ericdengbowen/dslrdnet。
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Artificial Intelligence (AI) has become commonplace to solve routine everyday tasks. Because of the exponential growth in medical imaging data volume and complexity, the workload on radiologists is steadily increasing. We project that the gap between the number of imaging exams and the number of expert radiologist readers required to cover this increase will continue to expand, consequently introducing a demand for AI-based tools that improve the efficiency with which radiologists can comfortably interpret these exams. AI has been shown to improve efficiency in medical-image generation, processing, and interpretation, and a variety of such AI models have been developed across research labs worldwide. However, very few of these, if any, find their way into routine clinical use, a discrepancy that reflects the divide between AI research and successful AI translation. To address the barrier to clinical deployment, we have formed MONAI Consortium, an open-source community which is building standards for AI deployment in healthcare institutions, and developing tools and infrastructure to facilitate their implementation. This report represents several years of weekly discussions and hands-on problem solving experience by groups of industry experts and clinicians in the MONAI Consortium. We identify barriers between AI-model development in research labs and subsequent clinical deployment and propose solutions. Our report provides guidance on processes which take an imaging AI model from development to clinical implementation in a healthcare institution. We discuss various AI integration points in a clinical Radiology workflow. We also present a taxonomy of Radiology AI use-cases. Through this report, we intend to educate the stakeholders in healthcare and AI (AI researchers, radiologists, imaging informaticists, and regulators) about cross-disciplinary challenges and possible solutions.
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SchNetPack is a versatile neural networks toolbox that addresses both the requirements of method development and application of atomistic machine learning. Version 2.0 comes with an improved data pipeline, modules for equivariant neural networks as well as a PyTorch implementation of molecular dynamics. An optional integration with PyTorch Lightning and the Hydra configuration framework powers a flexible command-line interface. This makes SchNetPack 2.0 easily extendable with custom code and ready for complex training task such as generation of 3d molecular structures.
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Generating realistic 3D worlds occupied by moving humans has many applications in games, architecture, and synthetic data creation. But generating such scenes is expensive and labor intensive. Recent work generates human poses and motions given a 3D scene. Here, we take the opposite approach and generate 3D indoor scenes given 3D human motion. Such motions can come from archival motion capture or from IMU sensors worn on the body, effectively turning human movement in a "scanner" of the 3D world. Intuitively, human movement indicates the free-space in a room and human contact indicates surfaces or objects that support activities such as sitting, lying or touching. We propose MIME (Mining Interaction and Movement to infer 3D Environments), which is a generative model of indoor scenes that produces furniture layouts that are consistent with the human movement. MIME uses an auto-regressive transformer architecture that takes the already generated objects in the scene as well as the human motion as input, and outputs the next plausible object. To train MIME, we build a dataset by populating the 3D FRONT scene dataset with 3D humans. Our experiments show that MIME produces more diverse and plausible 3D scenes than a recent generative scene method that does not know about human movement. Code and data will be available for research at https://mime.is.tue.mpg.de.
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Synthetic data generation has recently gained widespread attention as a more reliable alternative to traditional data anonymization. The involved methods are originally developed for image synthesis. Hence, their application to the typically tabular and relational datasets from healthcare, finance and other industries is non-trivial. While substantial research has been devoted to the generation of realistic tabular datasets, the study of synthetic relational databases is still in its infancy. In this paper, we combine the variational autoencoder framework with graph neural networks to generate realistic synthetic relational databases. We then apply the obtained method to two publicly available databases in computational experiments. The results indicate that real databases' structures are accurately preserved in the resulting synthetic datasets, even for large datasets with advanced data types.
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We develop a wall model for large-eddy simulation (LES) that takes into account various pressure-gradient effects using multi-agent reinforcement learning (MARL). The model is trained using low-Reynolds-number flow over periodic hills with agents distributed on the wall along the computational grid points. The model utilizes a wall eddy-viscosity formulation as the boundary condition, which is shown to provide better predictions of the mean velocity field, rather than the typical wall-shear stress formulation. Each agent receives states based on local instantaneous flow quantities at an off-wall location, computes a reward based on the estimated wall-shear stress, and provides an action to update the wall eddy viscosity at each time step. The trained wall model is validated in wall-modeled LES (WMLES) of flow over periodic hills at higher Reynolds numbers, and the results show the effectiveness of the model on flow with pressure gradients. The analysis of the trained model indicates that the model is capable of distinguishing between the various pressure gradient regimes present in the flow.
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Multi-agent artificial intelligence research promises a path to develop intelligent technologies that are more human-like and more human-compatible than those produced by "solipsistic" approaches, which do not consider interactions between agents. Melting Pot is a research tool developed to facilitate work on multi-agent artificial intelligence, and provides an evaluation protocol that measures generalization to novel social partners in a set of canonical test scenarios. Each scenario pairs a physical environment (a "substrate") with a reference set of co-players (a "background population"), to create a social situation with substantial interdependence between the individuals involved. For instance, some scenarios were inspired by institutional-economics-based accounts of natural resource management and public-good-provision dilemmas. Others were inspired by considerations from evolutionary biology, game theory, and artificial life. Melting Pot aims to cover a maximally diverse set of interdependencies and incentives. It includes the commonly-studied extreme cases of perfectly-competitive (zero-sum) motivations and perfectly-cooperative (shared-reward) motivations, but does not stop with them. As in real-life, a clear majority of scenarios in Melting Pot have mixed incentives. They are neither purely competitive nor purely cooperative and thus demand successful agents be able to navigate the resulting ambiguity. Here we describe Melting Pot 2.0, which revises and expands on Melting Pot. We also introduce support for scenarios with asymmetric roles, and explain how to integrate them into the evaluation protocol. This report also contains: (1) details of all substrates and scenarios; (2) a complete description of all baseline algorithms and results. Our intention is for it to serve as a reference for researchers using Melting Pot 2.0.
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We present a new perspective on loss minimization and the recent notion of Omniprediction through the lens of Outcome Indistingusihability. For a collection of losses and hypothesis class, omniprediction requires that a predictor provide a loss-minimization guarantee simultaneously for every loss in the collection compared to the best (loss-specific) hypothesis in the class. We present a generic template to learn predictors satisfying a guarantee we call Loss Outcome Indistinguishability. For a set of statistical tests--based on a collection of losses and hypothesis class--a predictor is Loss OI if it is indistinguishable (according to the tests) from Nature's true probabilities over outcomes. By design, Loss OI implies omniprediction in a direct and intuitive manner. We simplify Loss OI further, decomposing it into a calibration condition plus multiaccuracy for a class of functions derived from the loss and hypothesis classes. By careful analysis of this class, we give efficient constructions of omnipredictors for interesting classes of loss functions, including non-convex losses. This decomposition highlights the utility of a new multi-group fairness notion that we call calibrated multiaccuracy, which lies in between multiaccuracy and multicalibration. We show that calibrated multiaccuracy implies Loss OI for the important set of convex losses arising from Generalized Linear Models, without requiring full multicalibration. For such losses, we show an equivalence between our computational notion of Loss OI and a geometric notion of indistinguishability, formulated as Pythagorean theorems in the associated Bregman divergence. We give an efficient algorithm for calibrated multiaccuracy with computational complexity comparable to that of multiaccuracy. In all, calibrated multiaccuracy offers an interesting tradeoff point between efficiency and generality in the omniprediction landscape.
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安全至关重要的应用中神经网络(NNS)的患病率的增加,要求采用证明安全行为的方法。本文提出了一种向后的可及性方法,以安全验证神经反馈循环(NFLS),即具有NN控制策略的闭环系统。尽管最近的作品集中在远程达到NFL的安全认证策略上,但落后性能比远期策略具有优势,尤其是在避免障碍的情况下。先前的工作已经开发了用于无NNS系统的向后可及性分析的技术,但是由于其激活功能的非线性,反馈回路中的NNS存在唯一的问题,并且由于NN模型通常不可逆转。为了克服这些挑战,我们使用现有的NN分析工具有效地找到了对反射(BP)集的过度评估,即NN控制策略将将系统驱动到给定目标集的状态集。我们介绍了用于计算以馈电NN表示的控制策略的线性和非线性系统的BP过度评估的框架,并提出了计算有效的策略。我们使用各种模型的数值结果来展示所提出的算法,包括6D系统的安全认证。
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来自多个RGB摄像机的无标记人类运动捕获(MOCAP)是一个广泛研究的问题。现有方法要么需要校准相机,要么相对于静态摄像头校准它们,该摄像头是MOCAP系统的参考框架。每个捕获会话都必须先验完成校准步骤,这是一个乏味的过程,并且每当有意或意外移动相机时,都需要重新校准。在本文中,我们提出了一种MOCAP方法,该方法使用了多个静态和移动的外部未校准的RGB摄像机。我们方法的关键组成部分如下。首先,由于相机和受试者可以自由移动,因此我们选择接地平面作为常见参考,以代表身体和相机运动,与代表摄像机坐标中身体的现有方法不同。其次,我们了解相对于接地平面的短人类运动序列($ \ sim $ 1SEC)的概率分布,并利用它在摄像机和人类运动之间消除歧义。第三,我们将此分布用作一种新型的多阶段优化方法的运动,以适合SMPL人体模型,并且摄像机在图像上的人体关键点构成。最后,我们证明我们的方法可以在从航空摄像机到智能手机的各种数据集上使用。与使用静态摄像头的单眼人类MOCAP任务相比,它还提供了更准确的结果。我们的代码可在https://github.com/robot-ception-group/smartmocap上进行研究。
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