Training a Neural Radiance Field (NeRF) without pre-computed camera poses is challenging. Recent advances in this direction demonstrate the possibility of jointly optimising a NeRF and camera poses in forward-facing scenes. However, these methods still face difficulties during dramatic camera movement. We tackle this challenging problem by incorporating undistorted monocular depth priors. These priors are generated by correcting scale and shift parameters during training, with which we are then able to constrain the relative poses between consecutive frames. This constraint is achieved using our proposed novel loss functions. Experiments on real-world indoor and outdoor scenes show that our method can handle challenging camera trajectories and outperforms existing methods in terms of novel view rendering quality and pose estimation accuracy.
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神经隐式表示在新的视图合成和来自多视图图像的高质量3D重建方面显示了其有效性。但是,大多数方法都集中在整体场景表示上,但忽略了其中的各个对象,从而限制了潜在的下游应用程序。为了学习对象组合表示形式,一些作品将2D语义图作为训练中的提示,以掌握对象之间的差异。但是他们忽略了对象几何和实例语义信息之间的牢固联系,这导致了单个实例的不准确建模。本文提出了一个新颖的框架ObjectsDF,以在3D重建和对象表示中构建具有高保真度的对象复合神经隐式表示。观察常规音量渲染管道的歧义,我们通过组合单个对象的签名距离函数(SDF)来对场景进行建模,以发挥明确的表面约束。区分不同实例的关键是重新审视单个对象的SDF和语义标签之间的牢固关联。特别是,我们将语义信息转换为对象SDF的函数,并为场景和对象开发统一而紧凑的表示形式。实验结果表明,ObjectSDF框架在表示整体对象组合场景和各个实例方面的优越性。可以在https://qianyiwu.github.io/objectsdf/上找到代码
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在3D视觉中,视觉重新定位已被广泛讨论:鉴于预构建的3D视觉图,估计查询图像的6 DOF(自由度)姿势。大规模室内环境中的重新定位可实现有吸引力的应用程序,例如增强现实和机器人导航。但是,当相机移动时,在这种环境中,外观变化很快,这对于重新定位系统来说是具有挑战性的。为了解决这个问题,我们建议一种基于虚拟视图综合方法Rendernet,以丰富有关此特定情况的数据库和完善姿势。我们选择直接渲染虚拟观点的必要全局和本地特征,而不是渲染需要高质量3D模型的真实图像,并分别将它们应用于后续图像检索和功能匹配操作中。所提出的方法在很大程度上可以改善大规模室内环境中的性能,例如,在INLOC数据集中获得7.1 \%和12.2 \%的改善。
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人类姿势转移旨在将源人的外观转移到目标姿势。利用基于流量的非刚性人类图像的翘曲的现有方法取得了巨大的成功。然而,由于源和目标之间的空间相关性未充分利用,它们未能保留合成图像中的外观细节。为此,我们提出了基于流动的双重关注GaN(FDA-GaN),以应用于更高的发电质量的遮挡和变形感知功能融合。具体而言,可变形的局部注意力和流量相似性关注,构成双重关注机制,可以分别导出负责可变形和遮挡感知融合的输出特征。此外,为了维持传输的姿势和全球位置一致性,我们设计了一种姿势归一化网络,用于从目标姿势到源人员学习自适应标准化。定性和定量结果都表明,我们的方法在公共IPer和Deepfashion数据集中优于最先进的模型。
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在本文中,我们专注于人物图像的生成,即在各种条件下产生人物图像,例如腐败的纹理或不同的姿势。在此任务中解决纹理遮挡和大构成错位,以前的作品只使用相应的区域的风格来推断遮挡区域并依靠点明智的对齐来重新组织上下文纹理信息,缺乏全局关联地区的能力代码并保留源的局部结构。为了解决这些问题,我们提出了一种Glocal框架,通过全球推理不同语义区域之间的样式相互关系来改善遮挡感知纹理估计,这也可以用于恢复纹理染色中的损坏图像。对于本地结构信息保存,我们进一步提取了源图像的本地结构,并通过本地结构传输在所生成的图像中重新获得。我们基准测试我们的方法,以充分表征其对Deepfashion DataSet的性能,并显示出突出我们方法的新颖性的广泛消融研究。
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图表神经网络(GNNS)已成功利用在许多现实世界应用中的图形分析任务中。攻击和防御方法之间的竞争也增强了GNN的鲁棒性。在这次竞争中,对抗性培训方法的发展提出了对攻击例子的多样性要求。相比之下,大多数具有特定攻击策略的攻击方法难以满足这种要求。为了解决这个问题,我们提出了GraphAtcher,这是一种新型通用图形攻击框架,可根据图分析任务灵活地调整结构和攻击策略。通过在三个关键组件上的替代培训:基于生成对冲网络(GaN)的多策略攻击发生器(MAG),相似性鉴别器(SD)和攻击鉴别器(AD),产生对手示例。此外,考虑到节点相似性分布的变化,我们介绍了一种新颖的相似性修改率SMR来进行隐秘的攻击。在各种基准数据集上的实验表明,GraphAtcker可以在节点分类,图形分类和链路预测的图形分析任务上实现最先进的攻击性能,无论是否进行了对抗性培训。此外,我们还分析了每个任务的独特特征及其在统一攻击框架中的特定响应。项目代码可在https://github.com/honoluluuuu/graphatter处获得。
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In this paper, we propose a robust 3D detector, named Cross Modal Transformer (CMT), for end-to-end 3D multi-modal detection. Without explicit view transformation, CMT takes the image and point clouds tokens as inputs and directly outputs accurate 3D bounding boxes. The spatial alignment of multi-modal tokens is performed implicitly, by encoding the 3D points into multi-modal features. The core design of CMT is quite simple while its performance is impressive. CMT obtains 73.0% NDS on nuScenes benchmark. Moreover, CMT has a strong robustness even if the LiDAR is missing. Code will be released at https://github.com/junjie18/CMT.
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Dataset distillation has emerged as a prominent technique to improve data efficiency when training machine learning models. It encapsulates the knowledge from a large dataset into a smaller synthetic dataset. A model trained on this smaller distilled dataset can attain comparable performance to a model trained on the original training dataset. However, the existing dataset distillation techniques mainly aim at achieving the best trade-off between resource usage efficiency and model utility. The security risks stemming from them have not been explored. This study performs the first backdoor attack against the models trained on the data distilled by dataset distillation models in the image domain. Concretely, we inject triggers into the synthetic data during the distillation procedure rather than during the model training stage, where all previous attacks are performed. We propose two types of backdoor attacks, namely NAIVEATTACK and DOORPING. NAIVEATTACK simply adds triggers to the raw data at the initial distillation phase, while DOORPING iteratively updates the triggers during the entire distillation procedure. We conduct extensive evaluations on multiple datasets, architectures, and dataset distillation techniques. Empirical evaluation shows that NAIVEATTACK achieves decent attack success rate (ASR) scores in some cases, while DOORPING reaches higher ASR scores (close to 1.0) in all cases. Furthermore, we conduct a comprehensive ablation study to analyze the factors that may affect the attack performance. Finally, we evaluate multiple defense mechanisms against our backdoor attacks and show that our attacks can practically circumvent these defense mechanisms.
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Automatic music generation with artificial intelligence typically requires a large amount of data which is hard to obtain for many less common genres and musical instruments. To tackle this issue, we present ongoing work and preliminary findings on the possibility for deep models to transfer knowledge from language to music, by finetuning large language models pre-trained on a massive text corpus on only hundreds of MIDI files of drum performances. We show that by doing so, one of the largest, state-of-the-art models (GPT3) is capable of generating reasonable drum grooves, while models that are not pre-trained (Transformer) shows no such ability beyond naive repetition. Evaluating generated music is a challenging task, more so is evaluating drum grooves with little precedence in literature. Hence, we propose a tailored structural evaluation method and analyze drum grooves produced by GPT3 compared to those played by human professionals, exposing the strengths and weaknesses of such generation by language-to-music transfer. Our findings suggest that language-to-music transfer learning with large language models is viable and promising.
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Few Shot Instance Segmentation (FSIS) requires models to detect and segment novel classes with limited several support examples. In this work, we explore a simple yet unified solution for FSIS as well as its incremental variants, and introduce a new framework named Reference Twice (RefT) to fully explore the relationship between support/query features based on a Transformer-like framework. Our key insights are two folds: Firstly, with the aid of support masks, we can generate dynamic class centers more appropriately to re-weight query features. Secondly, we find that support object queries have already encoded key factors after base training. In this way, the query features can be enhanced twice from two aspects, i.e., feature-level and instance-level. In particular, we firstly design a mask-based dynamic weighting module to enhance support features and then propose to link object queries for better calibration via cross-attention. After the above steps, the novel classes can be improved significantly over our strong baseline. Additionally, our new framework can be easily extended to incremental FSIS with minor modification. When benchmarking results on the COCO dataset for FSIS, gFSIS, and iFSIS settings, our method achieves a competitive performance compared to existing approaches across different shots, e.g., we boost nAP by noticeable +8.2/+9.4 over the current state-of-the-art FSIS method for 10/30-shot. We further demonstrate the superiority of our approach on Few Shot Object Detection. Code and model will be available.
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