The capture and animation of human hair are two of the major challenges in the creation of realistic avatars for the virtual reality. Both problems are highly challenging, because hair has complex geometry and appearance, as well as exhibits challenging motion. In this paper, we present a two-stage approach that models hair independently from the head to address these challenges in a data-driven manner. The first stage, state compression, learns a low-dimensional latent space of 3D hair states containing motion and appearance, via a novel autoencoder-as-a-tracker strategy. To better disentangle the hair and head in appearance learning, we employ multi-view hair segmentation masks in combination with a differentiable volumetric renderer. The second stage learns a novel hair dynamics model that performs temporal hair transfer based on the discovered latent codes. To enforce higher stability while driving our dynamics model, we employ the 3D point-cloud autoencoder from the compression stage for de-noising of the hair state. Our model outperforms the state of the art in novel view synthesis and is capable of creating novel hair animations without having to rely on hair observations as a driving signal.
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我们提出了神经像素组成(NPC),这是一种连续3D-4D视图合成的新方法,只有一组离散的多视图观测值作为输入。现有的最新方法需要密集的多视图监督和广泛的计算预算。所提出的配方可靠地在稀疏和宽基线的多视图图像上运行,并且可以在几秒钟至10分钟内进行高分辨率(12MP)含量(即比现有方法快200-400x的收敛速度)进行有效训练。对我们的方法至关重要的是两个核心新颖性:1)像素的表示,其中包含从视线沿特定位置和时间的多视图中积累的颜色和深度信息,以及2)多层感知器(MLP)这使得为​​像素位置提供了这种丰富信息的组成,以获得最终的颜色输出。我们尝试了各种各样的多视图序列,与现有方法相比,并在各种和挑战性的环境中获得更好的结果。最后,我们的方法从稀疏的多视图中实现了密集的3D重建,其中Colmap是最先进的3D重建方法,挣扎。
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基于图像的体积人类使用像素对齐的特征有望泛化,从而看不见姿势和身份。先前的工作利用全局空间编码和多视图几何一致性来减少空间歧义。但是,全球编码通常会过度适应培训数据的分布,并且很难从稀疏视图中学习多视图一致的重建。在这项工作中,我们研究了现有空间编码的常见问题,并提出了一种简单而高效的方法,可以从稀疏视图中对高保真体积的人类进行建模。关键思想之一是通过稀疏3D关键点编码相对空间3D信息。这种方法对观点和跨数据库域间隙的稀疏性很强。我们的方法的表现优于头部重建的最先进方法。关于人体的重建是看不见的受试者,我们还实现了与使用参数人体模型和时间特征聚集的先前工作相当的性能。 Our experiments show that a majority of errors in prior work stem from an inappropriate choice of spatial encoding and thus we suggest a new direction for high-fidelity image-based human modeling. https://markomih.github.io/keypointnerf
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捕获和渲染寿命状的头发由于其细微的几何结构,复杂的物理相互作用及其非琐碎的视觉外观而特别具有挑战性。灰色是可信的头像的关键部件。在本文中,我们解决了上述问题:1)我们使用一种新的体积发型,这是成千上万的基元提出的。通过构建神经渲染的最新进步,每个原始可以有效地渲染。 2)具有可靠的控制信号,我们呈现了一种在股线水平上跟踪头发的新方法。为了保持计算努力,我们使用引导毛和经典技术将那些扩展到致密的头发罩中。 3)为了更好地强制执行我们模型的时间一致性和泛化能力,我们使用体积射线前导,进一步优化了我们的表示光流的3D场景流。我们的方法不仅可以创建录制的多视图序列的真实渲染,还可以通过提供新的控制信号来为新的头发配置创建渲染。我们将我们的方法与现有的方法进行比较,在视点合成和可驱动动画和实现最先进的结果。
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神经辐射场(NERFS)产生最先进的视图合成结果。然而,它们慢渲染,需要每像素数百个网络评估,以近似卷渲染积分。将nerfs烘烤到明确的数据结构中实现了有效的渲染,但导致内存占地面积的大幅增加,并且在许多情况下,质量降低。在本文中,我们提出了一种新的神经光场表示,相反,相反,紧凑,直接预测沿线的集成光线。我们的方法支持使用每个像素的单个网络评估,用于小基线光场数据集,也可以应用于每个像素的几个评估的较大基线。在我们的方法的核心,是一个光线空间嵌入网络,将4D射线空间歧管映射到中间可间可动子的潜在空间中。我们的方法在诸如斯坦福光场数据集等密集的前置数据集中实现了最先进的质量。此外,对于带有稀疏输入的面对面的场景,我们可以在质量方面实现对基于NERF的方法具有竞争力的结果,同时提供更好的速度/质量/内存权衡,网络评估较少。
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人类性能捕获是一种非常重要的计算机视觉问题,在电影制作和虚拟/增强现实中具有许多应用。许多以前的性能捕获方法需要昂贵的多视图设置,或者没有恢复具有帧到帧对应关系的密集时空相干几何。我们提出了一种新颖的深度致密人体性能捕获的深层学习方法。我们的方法是基于多视图监督的弱监督方式培训,完全删除了使用3D地面真理注释的培训数据的需求。网络架构基于两个单独的网络,将任务解散为姿势估计和非刚性表面变形步骤。广泛的定性和定量评估表明,我们的方法在质量和稳健性方面优于现有技术。这项工作是DeepCAP的扩展版本,在那里我们提供更详细的解释,比较和结果以及应用程序。
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综合照片 - 现实图像和视频是计算机图形的核心,并且是几十年的研究焦点。传统上,使用渲染算法(如光栅化或射线跟踪)生成场景的合成图像,其将几何形状和材料属性的表示为输入。统称,这些输入定义了实际场景和呈现的内容,并且被称为场景表示(其中场景由一个或多个对象组成)。示例场景表示是具有附带纹理的三角形网格(例如,由艺术家创建),点云(例如,来自深度传感器),体积网格(例如,来自CT扫描)或隐式曲面函数(例如,截短的符号距离)字段)。使用可分辨率渲染损耗的观察结果的这种场景表示的重建被称为逆图形或反向渲染。神经渲染密切相关,并将思想与经典计算机图形和机器学习中的思想相结合,以创建用于合成来自真实观察图像的图像的算法。神经渲染是朝向合成照片现实图像和视频内容的目标的跨越。近年来,我们通过数百个出版物显示了这一领域的巨大进展,这些出版物显示了将被动组件注入渲染管道的不同方式。这种最先进的神经渲染进步的报告侧重于将经典渲染原则与学习的3D场景表示结合的方法,通常现在被称为神经场景表示。这些方法的一个关键优势在于它们是通过设计的3D-一致,使诸如新颖的视点合成捕获场景的应用。除了处理静态场景的方法外,我们还涵盖了用于建模非刚性变形对象的神经场景表示...
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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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We present a dynamic path planning algorithm to navigate an amphibious rotor craft through a concave time-invariant obstacle field while attempting to minimize energy usage. We create a nonlinear quaternion state model that represents the rotor craft dynamics above and below the water. The 6 degree of freedom dynamics used within a layered architecture to generate motion paths for the vehicle to follow and the required control inputs. The rotor craft has a 3 dimensional map of its surroundings that is updated via limited range onboard sensor readings within the current medium (air or water). Path planning is done via PRM and D* Lite.
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While the capabilities of autonomous systems have been steadily improving in recent years, these systems still struggle to rapidly explore previously unknown environments without the aid of GPS-assisted navigation. The DARPA Subterranean (SubT) Challenge aimed to fast track the development of autonomous exploration systems by evaluating their performance in real-world underground search-and-rescue scenarios. Subterranean environments present a plethora of challenges for robotic systems, such as limited communications, complex topology, visually-degraded sensing, and harsh terrain. The presented solution enables long-term autonomy with minimal human supervision by combining a powerful and independent single-agent autonomy stack, with higher level mission management operating over a flexible mesh network. The autonomy suite deployed on quadruped and wheeled robots was fully independent, freeing the human supervision to loosely supervise the mission and make high-impact strategic decisions. We also discuss lessons learned from fielding our system at the SubT Final Event, relating to vehicle versatility, system adaptability, and re-configurable communications.
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