基于骨架的动作识别吸引了其对照明条件的计算效率和鲁棒性的关注。现有的基于骨架的动作识别方法通常是作为单次分类任务而不充分利用动作之间的语义关系的一项单次分类任务。例如,“胜利标志”和“拇指”是手势的两个动作,其主要区别在于手的运动。该信息是从分类的动作类别编码的不可知论,但可以在动作的语言描述中揭示。因此,在培训中利用动作语言描述可能会受益于代表性学习。在这项工作中,我们提出了一种基于骨架的动作识别的语言监督培训(LST)方法。更具体地说,我们采用大型语言模型作为知识引擎来为身体部件的动作运动提供文本描述,并通过利用文本编码器来生成特征向量来为不同的身体部位生成特征向量并监督多模式训练方案并监督动作表示学习的骨架编码器。实验表明,我们提出的LST方法在没有推理时没有额外的计算成本的情况下,对各种基线模型实现了明显的改进。 LST在基于流行的骨架的动作识别基准上实现了新的最新技术,包括NTU RGB+D,NTU RGB+D 120和NW-UCLA。该代码可以在https://github.com/martinxm/lst上找到。
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基于变压器的方法最近在基于2D图像的视力任务上取得了巨大进步。但是,对于基于3D视频的任务,例如动作识别,直接将时空变压器应用于视频数据将带来沉重的计算和记忆负担,因为斑块的数量大大增加以及自我注意计算的二次复杂性。如何对视频数据的3D自我注意力进行有效地建模,这对于变压器来说是一个巨大的挑战。在本文中,我们提出了一种时间贴片移动(TPS)方法,用于在变压器中有效的3D自发明建模,以进行基于视频的动作识别。 TPS在时间尺寸中以特定的镶嵌图模式移动斑块的一部分,从而将香草的空间自我发项操作转换为时空的一部分,几乎没有额外的成本。结果,我们可以使用几乎相同的计算和记忆成本来计算3D自我注意力。 TPS是一个插件模块,可以插入现有的2D变压器模型中,以增强时空特征学习。提出的方法可以通过最先进的V1和V1,潜水-48和Kinetics400实现竞争性能,同时在计算和内存成本方面效率更高。 TPS的源代码可在https://github.com/martinxm/tps上找到。
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最近,变形金刚在图像分类中表现出巨大的潜力,并在ImageNet基准测试中建立了最先进的结果。然而,与CNN相比,变压器会缓慢收敛,并且由于缺乏空间电感偏见而容易过度拟合低数据。这种空间电感偏见可能特别有益,因为输入图像的2D结构在变压器中不能很好地保存。在这项工作中,我们提出了空间先验增强的自我注意力(SP-SA),这是为视觉变压器量身定制的香草自我注意力(SA)的新型变体。空间先验(SP)是我们提出的归纳偏见家族,突出了某些空间关系。与卷积归纳偏见不同,被迫专注于硬编码的地方区域,我们提出的SP是由模型本身学到的,并考虑了各种空间关系。具体而言,注意力评分是在每个头部都强调某些空间关系的重点,并且这种学识渊博的空间灶可以彼此互补。基于SP-SA,我们提出了SP-VIT家族,该家族始终优于其他具有相似GFLOPS或参数的VIT模型。我们最大的型号SP-VIT-L与以前的最新模型相比,参数数量降低了近50%(SP-VIT-L 150m VS 271M的CAIT-M-36)在所有Imagenet-1K模型中,在224x224训练,并在384x384分辨率上进行了微调,该分辨率带有额外的数据。
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In contrast to the control-theoretic methods, the lack of stability guarantee remains a significant problem for model-free reinforcement learning (RL) methods. Jointly learning a policy and a Lyapunov function has recently become a promising approach to ensuring the whole system with a stability guarantee. However, the classical Lyapunov constraints researchers introduced cannot stabilize the system during the sampling-based optimization. Therefore, we propose the Adaptive Stability Certification (ASC), making the system reach sampling-based stability. Because the ASC condition can search for the optimal policy heuristically, we design the Adaptive Lyapunov-based Actor-Critic (ALAC) algorithm based on the ASC condition. Meanwhile, our algorithm avoids the optimization problem that a variety of constraints are coupled into the objective in current approaches. When evaluated on ten robotic tasks, our method achieves lower accumulated cost and fewer stability constraint violations than previous studies.
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A storyboard is a roadmap for video creation which consists of shot-by-shot images to visualize key plots in a text synopsis. Creating video storyboards however remains challenging which not only requires association between high-level texts and images, but also demands for long-term reasoning to make transitions smooth across shots. In this paper, we propose a new task called Text synopsis to Video Storyboard (TeViS) which aims to retrieve an ordered sequence of images to visualize the text synopsis. We construct a MovieNet-TeViS benchmark based on the public MovieNet dataset. It contains 10K text synopses each paired with keyframes that are manually selected from corresponding movies by considering both relevance and cinematic coherence. We also present an encoder-decoder baseline for the task. The model uses a pretrained vision-and-language model to improve high-level text-image matching. To improve coherence in long-term shots, we further propose to pre-train the decoder on large-scale movie frames without text. Experimental results demonstrate that our proposed model significantly outperforms other models to create text-relevant and coherent storyboards. Nevertheless, there is still a large gap compared to human performance suggesting room for promising future work.
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Retrieval-augmented in-context learning has emerged as a powerful approach for addressing knowledge-intensive tasks using frozen language models (LM) and retrieval models (RM). Existing work has combined these in simple "retrieve-then-read" pipelines in which the RM retrieves passages that are inserted into the LM prompt. To begin to fully realize the potential of frozen LMs and RMs, we propose Demonstrate-Search-Predict (DSP), a framework that relies on passing natural language texts in sophisticated pipelines between an LM and an RM. DSP can express high-level programs that bootstrap pipeline-aware demonstrations, search for relevant passages, and generate grounded predictions, systematically breaking down problems into small transformations that the LM and RM can handle more reliably. We have written novel DSP programs for answering questions in open-domain, multi-hop, and conversational settings, establishing in early evaluations new state-of-the-art in-context learning results and delivering 37-200%, 8-40%, and 80-290% relative gains against vanilla LMs, a standard retrieve-then-read pipeline, and a contemporaneous self-ask pipeline, respectively.
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Future work sentences (FWS) are the particular sentences in academic papers that contain the author's description of their proposed follow-up research direction. This paper presents methods to automatically extract FWS from academic papers and classify them according to the different future directions embodied in the paper's content. FWS recognition methods will enable subsequent researchers to locate future work sentences more accurately and quickly and reduce the time and cost of acquiring the corpus. The current work on automatic identification of future work sentences is relatively small, and the existing research cannot accurately identify FWS from academic papers, and thus cannot conduct data mining on a large scale. Furthermore, there are many aspects to the content of future work, and the subdivision of the content is conducive to the analysis of specific development directions. In this paper, Nature Language Processing (NLP) is used as a case study, and FWS are extracted from academic papers and classified into different types. We manually build an annotated corpus with six different types of FWS. Then, automatic recognition and classification of FWS are implemented using machine learning models, and the performance of these models is compared based on the evaluation metrics. The results show that the Bernoulli Bayesian model has the best performance in the automatic recognition task, with the Macro F1 reaching 90.73%, and the SCIBERT model has the best performance in the automatic classification task, with the weighted average F1 reaching 72.63%. Finally, we extract keywords from FWS and gain a deep understanding of the key content described in FWS, and we also demonstrate that content determination in FWS will be reflected in the subsequent research work by measuring the similarity between future work sentences and the abstracts.
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Heterogeneous graph contrastive learning has received wide attention recently. Some existing methods use meta-paths, which are sequences of object types that capture semantic relationships between objects, to construct contrastive views. However, most of them ignore the rich meta-path context information that describes how two objects are connected by meta-paths. On the other hand, they fail to distinguish hard negatives from false negatives, which could adversely affect the model performance. To address the problems, we propose MEOW, a heterogeneous graph contrastive learning model that considers both meta-path contexts and weighted negative samples. Specifically, MEOW constructs a coarse view and a fine-grained view for contrast. The former reflects which objects are connected by meta-paths, while the latter uses meta-path contexts and characterizes the details on how the objects are connected. We take node embeddings in the coarse view as anchors, and construct positive and negative samples from the fine-grained view. Further, to distinguish hard negatives from false negatives, we learn weights of negative samples based on node clustering. We also use prototypical contrastive learning to pull close embeddings of nodes in the same cluster. Finally, we conduct extensive experiments to show the superiority of MEOW against other state-of-the-art methods.
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Previous work has shown the potential of deep learning to predict renal obstruction using kidney ultrasound images. However, these image-based classifiers have been trained with the goal of single-visit inference in mind. We compare methods from video action recognition (i.e. convolutional pooling, LSTM, TSM) to adapt single-visit convolutional models to handle multiple visit inference. We demonstrate that incorporating images from a patient's past hospital visits provides only a small benefit for the prediction of obstructive hydronephrosis. Therefore, inclusion of prior ultrasounds is beneficial, but prediction based on the latest ultrasound is sufficient for patient risk stratification.
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Referring image segmentation aims to segment the target object described by a given natural language expression. Typically, referring expressions contain complex relationships between the target and its surrounding objects. The main challenge of this task is to understand the visual and linguistic content simultaneously and to find the referred object accurately among all instances in the image. Currently, the most effective way to solve the above problem is to obtain aligned multi-modal features by computing the correlation between visual and linguistic feature modalities under the supervision of the ground-truth mask. However, existing paradigms have difficulty in thoroughly understanding visual and linguistic content due to the inability to perceive information directly about surrounding objects that refer to the target. This prevents them from learning aligned multi-modal features, which leads to inaccurate segmentation. To address this issue, we present a position-aware contrastive alignment network (PCAN) to enhance the alignment of multi-modal features by guiding the interaction between vision and language through prior position information. Our PCAN consists of two modules: 1) Position Aware Module (PAM), which provides position information of all objects related to natural language descriptions, and 2) Contrastive Language Understanding Module (CLUM), which enhances multi-modal alignment by comparing the features of the referred object with those of related objects. Extensive experiments on three benchmarks demonstrate our PCAN performs favorably against the state-of-the-art methods. Our code will be made publicly available.
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