与其他技术(例如电感回路,雷达或激光器)相比,使用摄像头进行车速测量的成本效益要高得多。但是,由于相机的固有局限性提供准确的范围估计值,因此准确的速度测量仍然是一个挑战。此外,基于经典的视觉方法对相机和道路之间的外部校准非常敏感。在这种情况下,使用数据驱动的方法是一种有趣的选择。但是,数据收集需要一个复杂且昂贵的设置,以在与高精度速度传感器同步的相机中录制视频,以生成地面真相速度值。最近已经证明,使用驾驶模拟器(例如Carla)可以用作生成大型合成数据集的强大替代方案,以实现对单个摄像机的车辆速度估算的应用。在本文中,我们在不同的虚拟位置和不同的外部参数中使用多个摄像机研究相同的问题。我们解决了复杂的3D-CNN体系结构是否能够使用单个模型隐式学习视图速度的问题,或者特定于视图的模型是否更合适。结果非常有前途,因为它们表明具有来自多个视图的数据报告的单个模型比摄像机特异性模型更好地准确性,从而铺平了迈向视图的车辆速度测量系统。
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Motion prediction systems aim to capture the future behavior of traffic scenarios enabling autonomous vehicles to perform safe and efficient planning. The evolution of these scenarios is highly uncertain and depends on the interactions of agents with static and dynamic objects in the scene. GNN-based approaches have recently gained attention as they are well suited to naturally model these interactions. However, one of the main challenges that remains unexplored is how to address the complexity and opacity of these models in order to deal with the transparency requirements for autonomous driving systems, which includes aspects such as interpretability and explainability. In this work, we aim to improve the explainability of motion prediction systems by using different approaches. First, we propose a new Explainable Heterogeneous Graph-based Policy (XHGP) model based on an heterograph representation of the traffic scene and lane-graph traversals, which learns interaction behaviors using object-level and type-level attention. This learned attention provides information about the most important agents and interactions in the scene. Second, we explore this same idea with the explanations provided by GNNExplainer. Third, we apply counterfactual reasoning to provide explanations of selected individual scenarios by exploring the sensitivity of the trained model to changes made to the input data, i.e., masking some elements of the scene, modifying trajectories, and adding or removing dynamic agents. The explainability analysis provided in this paper is a first step towards more transparent and reliable motion prediction systems, important from the perspective of the user, developers and regulatory agencies. The code to reproduce this work is publicly available at https://github.com/sancarlim/Explainable-MP/tree/v1.1.
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这项工作提出了一种新的方法,可以使用有效的鸟类视图表示和卷积神经网络在高速公路场景中预测车辆轨迹。使用基本的视觉表示,很容易将车辆位置,运动历史,道路配置和车辆相互作用轻松包含在预测模型中。 U-NET模型已被选为预测内核,以使用图像到图像回归方法生成场景的未来视觉表示。已经实施了一种方法来从生成的图形表示中提取车辆位置以实现子像素分辨率。该方法已通过预防数据集(一个板载传感器数据集)进行了培训和评估。已经评估了不同的网络配置和场景表示。这项研究发现,使用线性终端层和车辆的高斯表示,具有6个深度水平的U-NET是最佳性能配置。发现使用车道标记不会改善预测性能。平均预测误差为0.47和0.38米,对于纵向和横向坐标的最终预测误差分别为0.76和0.53米,预测轨迹长度为2.0秒。与基线方法相比,预测误差低至50%。
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由于需要快速原型制作和广泛的测试,模拟在自主驾驶中的作用变得越来越重要。基于物理的模拟使用涉及多个利益和优势,以合理的成本消除了对原型,驱动因素和脆弱道路使用者的风险。但是,有两个主要局限性。首先,众所周知的现实差距是指现实与模拟之间的差异,这阻止了模拟自主驾驶体验实现有效的现实性能。其次,缺乏有关真实代理商的行为的经验知识,包括备用驾驶员或乘客以及其他道路使用者,例如车辆,行人或骑自行车的人。代理仿真通常是根据实际数据进行确定性,随机概率或生成的预编程的,但它不代表与特定模拟方案相互作用的真实试剂的行为。在本文中,我们提出了一个初步框架,以实现真实试剂与模拟环境(包括自动驾驶汽车)之间的实时互动,并从多个视图中从模拟传感器数据中生成合成序列,这些视图可用于培训依赖行为模型的预测系统。我们的方法将沉浸式的虚拟现实和人类运动捕获系统与Carla模拟器进行自主驾驶。我们描述了提出的硬件和软件体系结构,并讨论所谓的行为差距或存在。我们提出了支持这种方法的潜力并讨论未来步骤的初步但有希望的结果。
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我们在右审查的生存时间和协变量之间介绍一般的非参数独立测试,这可能是多变量的。我们的测试统计数据具有双重解释,首先是潜在无限的重量索引日志秩检验的超级索引,具有属于函数的再现内核HILBERT空间(RKHS)的重量函数;其次,作为某些有限措施的嵌入差异的规范,与Hilbert-Schmidt独立性标准(HSIC)测试统计类似。我们研究了测试的渐近性质,找到了足够的条件,以确保我们的测试在任何替代方案下正确拒绝零假设。可以直截了当地计算测试统计,并且通过渐近总体的野外自注程序进行拒绝阈值。对模拟和实际数据的广泛调查表明,我们的测试程序通常比检测复杂的非线性依赖的竞争方法更好。
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In this paper, we propose a novel technique, namely INVALIDATOR, to automatically assess the correctness of APR-generated patches via semantic and syntactic reasoning. INVALIDATOR reasons about program semantic via program invariants while it also captures program syntax via language semantic learned from large code corpus using the pre-trained language model. Given a buggy program and the developer-patched program, INVALIDATOR infers likely invariants on both programs. Then, INVALIDATOR determines that a APR-generated patch overfits if: (1) it violates correct specifications or (2) maintains errors behaviors of the original buggy program. In case our approach fails to determine an overfitting patch based on invariants, INVALIDATOR utilizes a trained model from labeled patches to assess patch correctness based on program syntax. The benefit of INVALIDATOR is three-fold. First, INVALIDATOR is able to leverage both semantic and syntactic reasoning to enhance its discriminant capability. Second, INVALIDATOR does not require new test cases to be generated but instead only relies on the current test suite and uses invariant inference to generalize the behaviors of a program. Third, INVALIDATOR is fully automated. We have conducted our experiments on a dataset of 885 patches generated on real-world programs in Defects4J. Experiment results show that INVALIDATOR correctly classified 79% overfitting patches, accounting for 23% more overfitting patches being detected by the best baseline. INVALIDATOR also substantially outperforms the best baselines by 14% and 19% in terms of Accuracy and F-Measure, respectively.
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The recent increase in public and academic interest in preserving biodiversity has led to the growth of the field of conservation technology. This field involves designing and constructing tools that utilize technology to aid in the conservation of wildlife. In this article, we will use case studies to demonstrate the importance of designing conservation tools with human-wildlife interaction in mind and provide a framework for creating successful tools. These case studies include a range of complexities, from simple cat collars to machine learning and game theory methodologies. Our goal is to introduce and inform current and future researchers in the field of conservation technology and provide references for educating the next generation of conservation technologists. Conservation technology not only has the potential to benefit biodiversity but also has broader impacts on fields such as sustainability and environmental protection. By using innovative technologies to address conservation challenges, we can find more effective and efficient solutions to protect and preserve our planet's resources.
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Numerous works use word embedding-based metrics to quantify societal biases and stereotypes in texts. Recent studies have found that word embeddings can capture semantic similarity but may be affected by word frequency. In this work we study the effect of frequency when measuring female vs. male gender bias with word embedding-based bias quantification methods. We find that Skip-gram with negative sampling and GloVe tend to detect male bias in high frequency words, while GloVe tends to return female bias in low frequency words. We show these behaviors still exist when words are randomly shuffled. This proves that the frequency-based effect observed in unshuffled corpora stems from properties of the metric rather than from word associations. The effect is spurious and problematic since bias metrics should depend exclusively on word co-occurrences and not individual word frequencies. Finally, we compare these results with the ones obtained with an alternative metric based on Pointwise Mutual Information. We find that this metric does not show a clear dependence on frequency, even though it is slightly skewed towards male bias across all frequencies.
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Variational autoencoders model high-dimensional data by positing low-dimensional latent variables that are mapped through a flexible distribution parametrized by a neural network. Unfortunately, variational autoencoders often suffer from posterior collapse: the posterior of the latent variables is equal to its prior, rendering the variational autoencoder useless as a means to produce meaningful representations. Existing approaches to posterior collapse often attribute it to the use of neural networks or optimization issues due to variational approximation. In this paper, we consider posterior collapse as a problem of latent variable non-identifiability. We prove that the posterior collapses if and only if the latent variables are non-identifiable in the generative model. This fact implies that posterior collapse is not a phenomenon specific to the use of flexible distributions or approximate inference. Rather, it can occur in classical probabilistic models even with exact inference, which we also demonstrate. Based on these results, we propose a class of latent-identifiable variational autoencoders, deep generative models which enforce identifiability without sacrificing flexibility. This model class resolves the problem of latent variable non-identifiability by leveraging bijective Brenier maps and parameterizing them with input convex neural networks, without special variational inference objectives or optimization tricks. Across synthetic and real datasets, latent-identifiable variational autoencoders outperform existing methods in mitigating posterior collapse and providing meaningful representations of the data.
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Cashews are grown by over 3 million smallholders in more than 40 countries worldwide as a principal source of income. As the third largest cashew producer in Africa, Benin has nearly 200,000 smallholder cashew growers contributing 15% of the country's national export earnings. However, a lack of information on where and how cashew trees grow across the country hinders decision-making that could support increased cashew production and poverty alleviation. By leveraging 2.4-m Planet Basemaps and 0.5-m aerial imagery, newly developed deep learning algorithms, and large-scale ground truth datasets, we successfully produced the first national map of cashew in Benin and characterized the expansion of cashew plantations between 2015 and 2021. In particular, we developed a SpatioTemporal Classification with Attention (STCA) model to map the distribution of cashew plantations, which can fully capture texture information from discriminative time steps during a growing season. We further developed a Clustering Augmented Self-supervised Temporal Classification (CASTC) model to distinguish high-density versus low-density cashew plantations by automatic feature extraction and optimized clustering. Results show that the STCA model has an overall accuracy of 80% and the CASTC model achieved an overall accuracy of 77.9%. We found that the cashew area in Benin has doubled from 2015 to 2021 with 60% of new plantation development coming from cropland or fallow land, while encroachment of cashew plantations into protected areas has increased by 70%. Only half of cashew plantations were high-density in 2021, suggesting high potential for intensification. Our study illustrates the power of combining high-resolution remote sensing imagery and state-of-the-art deep learning algorithms to better understand tree crops in the heterogeneous smallholder landscape.
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