3D shapes have complementary abstractions from low-level geometry to part-based hierarchies to languages, which convey different levels of information. This paper presents a unified framework to translate between pairs of shape abstractions: $\textit{Text}$ $\Longleftrightarrow$ $\textit{Point Cloud}$ $\Longleftrightarrow$ $\textit{Program}$. We propose $\textbf{Neural Shape Compiler}$ to model the abstraction transformation as a conditional generation process. It converts 3D shapes of three abstract types into unified discrete shape code, transforms each shape code into code of other abstract types through the proposed $\textit{ShapeCode Transformer}$, and decodes them to output the target shape abstraction. Point Cloud code is obtained in a class-agnostic way by the proposed $\textit{Point}$VQVAE. On Text2Shape, ShapeGlot, ABO, Genre, and Program Synthetic datasets, Neural Shape Compiler shows strengths in $\textit{Text}$ $\Longrightarrow$ $\textit{Point Cloud}$, $\textit{Point Cloud}$ $\Longrightarrow$ $\textit{Text}$, $\textit{Point Cloud}$ $\Longrightarrow$ $\textit{Program}$, and Point Cloud Completion tasks. Additionally, Neural Shape Compiler benefits from jointly training on all heterogeneous data and tasks.

Point cloud completion is a generation and estimation issue derived from the partial point clouds, which plays a vital role in the applications in 3D computer vision. The progress of deep learning (DL) has impressively improved the capability and robustness of point cloud completion. However, the quality of completed point clouds is still needed to be further enhanced to meet the practical utilization. Therefore, this work aims to conduct a comprehensive survey on various methods, including point-based, convolution-based, graph-based, and generative model-based approaches, etc. And this survey summarizes the comparisons among these methods to provoke further research insights. Besides, this review sums up the commonly used datasets and illustrates the applications of point cloud completion. Eventually, we also discussed possible research trends in this promptly expanding field.

While recent work on text-conditional 3D object generation has shown promising results, the state-of-the-art methods typically require multiple GPU-hours to produce a single sample. This is in stark contrast to state-of-the-art generative image models, which produce samples in a number of seconds or minutes. In this paper, we explore an alternative method for 3D object generation which produces 3D models in only 1-2 minutes on a single GPU. Our method first generates a single synthetic view using a text-to-image diffusion model, and then produces a 3D point cloud using a second diffusion model which conditions on the generated image. While our method still falls short of the state-of-the-art in terms of sample quality, it is one to two orders of magnitude faster to sample from, offering a practical trade-off for some use cases. We release our pre-trained point cloud diffusion models, as well as evaluation code and models, at https://github.com/openai/point-e.

Three-dimensional geometric data offer an excellent domain for studying representation learning and generative modeling. In this paper, we look at geometric data represented as point clouds. We introduce a deep AutoEncoder (AE) network with state-of-the-art reconstruction quality and generalization ability. The learned representations outperform existing methods on 3D recognition tasks and enable shape editing via simple algebraic manipulations, such as semantic part editing, shape analogies and shape interpolation, as well as shape completion. We perform a thorough study of different generative models including GANs operating on the raw point clouds, significantly improved GANs trained in the fixed latent space of our AEs, and Gaussian Mixture Models (GMMs). To quantitatively evaluate generative models we introduce measures of sample fidelity and diversity based on matchings between sets of point clouds. Interestingly, our evaluation of generalization, fidelity and diversity reveals that GMMs trained in the latent space of our AEs yield the best results overall.

给定日常工件，例如桌子和椅子，人类识别其中的高级规律性，例如桌子的对称性，腿的重复，同时拥有低级的几何学，例如，表面是平稳的，边缘是光滑的，边缘是光滑的。锋利。这种知识构成了人类感知理解和推理的重要组成部分。在这种知识中的表现以及如何推理，以及其获取的习得仍然是人工智能（AI）和认知科学中的开放问题。基于\ emph {3D形状程序}的先前建议，单独使用\ citet {tian2019llear}的随附的神经发电机和执行者，我们提出了一个分析性但可不同的执行者，在解释形状程序中更忠实，可以控制外推）和更有效的样本效率（不需要培训）。当无法获得地面真理程序时，这些促进了发电机的学习，当人类设计师或 - 在图书馆学习的背景下，当新的形状编程组件被录入时，应该特别有用。关于使用它进行适应的初步实验说明了所提出的模块的上述优势，鼓励在建筑机器中探索类似的方法，这些方法学会通过上述知识来推理推理，甚至学习这些知识本身。

随着信息中的各种方式存在于现实世界中的各种方式，多式联信息之间的有效互动和融合在计算机视觉和深度学习研究中的多模式数据的创造和感知中起着关键作用。通过卓越的功率，在多式联运信息中建模互动，多式联运图像合成和编辑近年来已成为一个热门研究主题。与传统的视觉指导不同，提供明确的线索，多式联路指南在图像合成和编辑方面提供直观和灵活的手段。另一方面，该领域也面临着具有固有的模态差距的特征的几个挑战，高分辨率图像的合成，忠实的评估度量等。在本调查中，我们全面地阐述了最近多式联运图像综合的进展根据数据模型和模型架构编辑和制定分类。我们从图像合成和编辑中的不同类型的引导方式开始介绍。然后，我们描述了多模式图像综合和编辑方法，其具有详细的框架，包括生成的对抗网络（GAN），GaN反转，变压器和其他方法，例如NERF和扩散模型。其次是在多模式图像合成和编辑中广泛采用的基准数据集和相应的评估度量的综合描述，以及分析各个优点和限制的不同合成方法的详细比较。最后，我们为目前的研究挑战和未来的研究方向提供了深入了解。与本调查相关的项目可在HTTPS://github.com/fnzhan/mise上获得

由于没有大型配对的文本形状数据，这两种方式之间的大量语义差距以及3D形状的结构复杂性，因此文本指导的3D形状生成仍然具有挑战性。本文通过引入2D图像作为垫脚石来连接两种方式并消除对配对的文本形状数据的需求，提出了一个名为“图像”的新框架，称为“垫脚石”（ISS）。我们的关键贡献是一种两阶段的功能空间对准方法，它通过利用具有多视图Supperions的预训练的单视重构造（SVR）模型来映射剪辑功能以形成形状：首先将剪辑图像剪辑剪辑功能到详细信息 - SVR模型中的丰富形状空间，然后将剪辑文本功能映射到形状空间，并通过鼓励输入文本和渲染图像之间的剪辑一致性来优化映射。此外，我们制定了一个文本制定的形状样式化模块，以用新颖的纹理打扮出输出形状。除了从文本上生成3D Shape生成的现有作品外，我们的新方法是在不需要配对的文本形状数据的情况下创建形状的一般性。实验结果表明，我们的方法在忠诚度和与文本一致性方面优于最先进的和我们的基线。此外，我们的方法可以通过逼真的和幻想结构和纹理对生成的形状进行样式化。

Generative models, as an important family of statistical modeling, target learning the observed data distribution via generating new instances. Along with the rise of neural networks, deep generative models, such as variational autoencoders (VAEs) and generative adversarial network (GANs), have made tremendous progress in 2D image synthesis. Recently, researchers switch their attentions from the 2D space to the 3D space considering that 3D data better aligns with our physical world and hence enjoys great potential in practice. However, unlike a 2D image, which owns an efficient representation (i.e., pixel grid) by nature, representing 3D data could face far more challenges. Concretely, we would expect an ideal 3D representation to be capable enough to model shapes and appearances in details, and to be highly efficient so as to model high-resolution data with fast speed and low memory cost. However, existing 3D representations, such as point clouds, meshes, and recent neural fields, usually fail to meet the above requirements simultaneously. In this survey, we make a thorough review of the development of 3D generation, including 3D shape generation and 3D-aware image synthesis, from the perspectives of both algorithms and more importantly representations. We hope that our discussion could help the community track the evolution of this field and further spark some innovative ideas to advance this challenging task.

Text-guided 3D object generation aims to generate 3D objects described by user-defined captions, which paves a flexible way to visualize what we imagined. Although some works have been devoted to solving this challenging task, these works either utilize some explicit 3D representations (e.g., mesh), which lack texture and require post-processing for rendering photo-realistic views; or require individual time-consuming optimization for every single case. Here, we make the first attempt to achieve generic text-guided cross-category 3D object generation via a new 3D-TOGO model, which integrates a text-to-views generation module and a views-to-3D generation module. The text-to-views generation module is designed to generate different views of the target 3D object given an input caption. prior-guidance, caption-guidance and view contrastive learning are proposed for achieving better view-consistency and caption similarity. Meanwhile, a pixelNeRF model is adopted for the views-to-3D generation module to obtain the implicit 3D neural representation from the previously-generated views. Our 3D-TOGO model generates 3D objects in the form of the neural radiance field with good texture and requires no time-cost optimization for every single caption. Besides, 3D-TOGO can control the category, color and shape of generated 3D objects with the input caption. Extensive experiments on the largest 3D object dataset (i.e., ABO) are conducted to verify that 3D-TOGO can better generate high-quality 3D objects according to the input captions across 98 different categories, in terms of PSNR, SSIM, LPIPS and CLIP-score, compared with text-NeRF and Dreamfields.

本文通过学习的基于零件的自相似性解决了无监督的零件感知点云产生的问题。我们的SPA-VAE可为任何给定物体提供一组潜在的典型候选形状，以及每种此类候选形状的一组刚体转换，以在组装的对象中为一个或多个位置。通过这种方式，可以有效地组合在表面上的嘈杂样品，以估计单腿原型。当原始数据中存在基于零件的自相似性时，以这种方式共享数据会赋予许多优势：建模准确性，适当的自相似生成输出，闭塞的精确填充和模型简约。 Spa-vae是使用各种贝叶斯方法的端到端训练的，该方法使用Gumbel-Softmax Trick进行共享零件分配，并提供各种新颖的损失，以提供适当的电感偏见。对塑料的定量和定性分析证明了SPA-VAE的优势。

3D点云是捕获真实世界3D对象的重要3D表示。但是，真正扫描的3D点云通常不完整，并且对于恢复下游应用程序的完整点云非常重要。大多数现有点云完成方法使用倒角距离（CD）训练丢失。通过搜索最近的邻居，CD损耗估计两个点云之间的对应关系，该邻居不会捕获所生成的形状上的总点密度分布，因此可能导致非均匀的点云生成。为了解决这个问题，我们提出了一个新的点扩散细化（PDR）范例，用于点云完成。 PDR包括条件生成网络（CGNET）和细化网络（RFNET）。 CGNET使用称为去噪扩散概率模型（DDPM）的条件生成模型，以在部分观察中产生粗略完成。 DDPM在生成的点云和统一的地面真理之间建立一对一的映射，然后优化平均平方误差损耗以实现均匀生成。 RFNET精制CGNet的粗输出，并进一步提高完成点云的质量。此外，我们开发了两个网络的新型双路架构。该体系结构可以（1）有效且有效地从部分观察到的点云提取多级特征以指导完成，并且（2）精确地操纵3D点的空间位置以获得平滑的表面和尖锐的细节。各种基准数据集上的广泛实验结果表明，我们的PDR范例优于以前的最先进的方法，用于点云完成。值得注意的是，在RFNET的帮助下，我们可以在没有太多的性能下降的情况下加速DDPM的迭代生成过程。

With the rising industrial attention to 3D virtual modeling technology, generating novel 3D content based on specified conditions (e.g. text) has become a hot issue. In this paper, we propose a new generative 3D modeling framework called Diffusion-SDF for the challenging task of text-to-shape synthesis. Previous approaches lack flexibility in both 3D data representation and shape generation, thereby failing to generate highly diversified 3D shapes conforming to the given text descriptions. To address this, we propose a SDF autoencoder together with the Voxelized Diffusion model to learn and generate representations for voxelized signed distance fields (SDFs) of 3D shapes. Specifically, we design a novel UinU-Net architecture that implants a local-focused inner network inside the standard U-Net architecture, which enables better reconstruction of patch-independent SDF representations. We extend our approach to further text-to-shape tasks including text-conditioned shape completion and manipulation. Experimental results show that Diffusion-SDF is capable of generating both high-quality and highly diversified 3D shapes that conform well to the given text descriptions. Diffusion-SDF has demonstrated its superiority compared to previous state-of-the-art text-to-shape approaches.

Diffusion models have shown great promise for image generation, beating GANs in terms of generation diversity, with comparable image quality. However, their application to 3D shapes has been limited to point or voxel representations that can in practice not accurately represent a 3D surface. We propose a diffusion model for neural implicit representations of 3D shapes that operates in the latent space of an auto-decoder. This allows us to generate diverse and high quality 3D surfaces. We additionally show that we can condition our model on images or text to enable image-to-3D generation and text-to-3D generation using CLIP embeddings. Furthermore, adding noise to the latent codes of existing shapes allows us to explore shape variations.

您将如何通过一些错过来修复物理物体？您可能会想象它的原始形状从先前捕获的图像中，首先恢复其整体（全局）但粗大的形状，然后完善其本地细节。我们有动力模仿物理维修程序以解决点云完成。为此，我们提出了一个跨模式的形状转移双转化网络（称为CSDN），这是一种带有全循环参与图像的粗到精细范式，以完成优质的点云完成。 CSDN主要由“ Shape Fusion”和“ Dual-Refinect”模块组成，以应对跨模式挑战。第一个模块将固有的形状特性从单个图像传输，以指导点云缺失区域的几何形状生成，在其中，我们建议iPadain嵌入图像的全局特征和部分点云的完成。第二个模块通过调整生成点的位置来完善粗糙输出，其中本地改进单元通过图卷积利用了小说和输入点之间的几何关系，而全局约束单元则利用输入图像来微调生成的偏移。与大多数现有方法不同，CSDN不仅探讨了图像中的互补信息，而且还可以在整个粗到精细的完成过程中有效利用跨模式数据。实验结果表明，CSDN对十个跨模式基准的竞争对手表现出色。

The success of deep learning heavily relies on large-scale data with comprehensive labels, which is more expensive and time-consuming to fetch in 3D compared to 2D images or natural languages. This promotes the potential of utilizing models pretrained with data more than 3D as teachers for cross-modal knowledge transferring. In this paper, we revisit masked modeling in a unified fashion of knowledge distillation, and we show that foundational Transformers pretrained with 2D images or natural languages can help self-supervised 3D representation learning through training Autoencoders as Cross-Modal Teachers (ACT). The pretrained Transformers are transferred as cross-modal 3D teachers using discrete variational autoencoding self-supervision, during which the Transformers are frozen with prompt tuning for better knowledge inheritance. The latent features encoded by the 3D teachers are used as the target of masked point modeling, wherein the dark knowledge is distilled to the 3D Transformer students as foundational geometry understanding. Our ACT pretrained 3D learner achieves state-of-the-art generalization capacity across various downstream benchmarks, e.g., 88.21% overall accuracy on ScanObjectNN. Codes will be released at https://github.com/RunpeiDong/ACT.

连接视觉和语言在生成智能中起着重要作用。因此，已经致力于图像标题的大型研究工作，即用句法和语义有意义的句子描述图像。从2015年开始，该任务通常通过由Visual Encoder组成的管道和文本生成的语言模型来解决任务。在这些年来，两种组件通过对象区域，属性，介绍多模态连接，完全关注方法和伯特早期融合策略的利用而显着发展。但是，无论令人印象深刻的结果，图像标题的研究还没有达到结论性答案。这项工作旨在提供图像标题方法的全面概述，从视觉编码和文本生成到培训策略，数据集和评估度量。在这方面，我们量化地比较了许多相关的最先进的方法来确定架构和培训策略中最有影响力的技术创新。此外，讨论了问题的许多变体及其开放挑战。这项工作的最终目标是作为理解现有文献的工具，并突出显示计算机视觉和自然语言处理的研究领域的未来方向可以找到最佳的协同作用。

Point clouds captured by scanning devices are often incomplete due to occlusion. Point cloud completion aims to predict the complete shape based on its partial input. Existing methods can be classified into supervised and unsupervised methods. However, both of them require a large number of 3D complete point clouds, which are difficult to capture. In this paper, we propose Cross-PCC, an unsupervised point cloud completion method without requiring any 3D complete point clouds. We only utilize 2D images of the complete objects, which are easier to capture than 3D complete and clean point clouds. Specifically, to take advantage of the complementary information from 2D images, we use a single-view RGB image to extract 2D features and design a fusion module to fuse the 2D and 3D features extracted from the partial point cloud. To guide the shape of predicted point clouds, we project the predicted points of the object to the 2D plane and use the foreground pixels of its silhouette maps to constrain the position of the projected points. To reduce the outliers of the predicted point clouds, we propose a view calibrator to move the points projected to the background into the foreground by the single-view silhouette image. To the best of our knowledge, our approach is the first point cloud completion method that does not require any 3D supervision. The experimental results of our method are superior to those of the state-of-the-art unsupervised methods by a large margin. Moreover, compared to some supervised methods, our method achieves similar performance. We will make the source code publicly available at https://github.com/ltwu6/cross-pcc.

我们提出了Kkexgen，这是一种用于计算机辅助设计（CAD）构造序列的新型自回旋生成模型，其中包含草图和伸出的建模操作。我们的模型利用不同的变压器体系结构编码构造序列的拓扑，几何和挤压变化为分离的代码簿。自回归变压器解码器生成CAD构造序列，共享代码簿向量指定的某些属性。广泛的实验表明，我们的删除代码书表示会生成多样化和高质量的CAD模型，增强用户控制，并有效地探索设计空间。该代码可在https://samxuxiang.github.io/skexgen上找到。

点云完成任务旨在预测不完整的点云的缺失部分，并通过详细信息生成完整的点云。在本文中，我们提出了一个新颖的点云完成网络，即完成。具体而言，从具有不同分辨率的点云中学到了特征，该分辨率是从不完整输入中采样的，并根据几何结构转换为一系列\ textit {spots}。然后，提出了基于变压器的密集关系增强模块（DRA），以学习\ textit {spots}中的特征，并考虑这些\ textit {spots}之间的相关性。 DRA由点局部注意模块（PLA）和点密集的多尺度注意模块（PDMA）组成，其中PLA通过适应邻居的权重，PDMA Expolo the Local \ textit {spots}捕获本地信息。这些\ textit {spots}之间的全局关系以多尺度的密集连接方式。最后，由\ textit {spots}通过多分辨率点融合模块（MPF）预测完整形状，该模块（mpf）逐渐从\ textit {spots}中逐渐生成完整的点云，并基于这些生成的点进行更新\ textit {spots}云。实验结果表明，由于基于变压器的DRA可以从不完整的输入中学习表达性特征，并且MPF可以完全探索这些功能以预测完整的输入，因此我们的方法在很大程度上优于先进方法。

Figure 1: DeepSDF represents signed distance functions (SDFs) of shapes via latent code-conditioned feed-forward decoder networks. Above images are raycast renderings of DeepSDF interpolating between two shapes in the learned shape latent space. Best viewed digitally.