Creating diverse and high-quality 3D assets with an automatic generative model is highly desirable. Despite extensive efforts on 3D generation, most existing works focus on the generation of a single category or a few categories. In this paper, we introduce a diffusion-based feed-forward framework for synthesizing massive categories of real-world 3D objects with a single generative model. Notably, there are three major challenges for this large-vocabulary 3D generation: a) the need for expressive yet efficient 3D representation; b) large diversity in geometry and texture across categories; c) complexity in the appearances of real-world objects. To this end, we propose a novel triplane-based 3D-aware Diffusion model with TransFormer, DiffTF, for handling challenges via three aspects. 1) Considering efficiency and robustness, we adopt a revised triplane representation and improve the fitting speed and accuracy. 2) To handle the drastic variations in geometry and texture, we regard the features of all 3D objects as a combination of generalized 3D knowledge and specialized 3D features. To extract generalized 3D knowledge from diverse categories, we propose a novel 3D-aware transformer with shared cross-plane attention. It learns the cross-plane relations across different planes and aggregates the generalized 3D knowledge with specialized 3D features. 3) In addition, we devise the 3D-aware encoder/decoder to enhance the generalized 3D knowledge in the encoded triplanes for handling categories with complex appearances. Extensive experiments on ShapeNet and OmniObject3D (over 200 diverse real-world categories) convincingly demonstrate that a single DiffTF model achieves state-of-the-art large-vocabulary 3D object generation performance with large diversity, rich semantics, and high quality.

翻译：通过自动生成模型创建多样化且高质量的三维资产极具吸引力。尽管三维生成领域已开展大量研究，但现有工作大多聚焦于单个或少数类别的生成。本文提出一种基于扩散的前馈框架，可通过单个生成模型合成海量类别的真实世界三维对象。值得注意的是，大词汇量三维生成面临三大挑战：a) 需要兼具表达力与高效性的三维表征；b) 不同类别间几何与纹理的极大差异性；c) 真实世界物体外观的复杂性。为此，我们提出新型三平面感知三维扩散Transformer（DiffTF），通过三方面应对挑战：1) 兼顾效率与鲁棒性，采用改进的三平面表征并提升拟合速度与精度；2) 为处理几何与纹理的剧烈变化，将所有三维对象的特征视为通用三维知识与专用三维特征的组合。为从多类别中提取通用三维知识，我们提出带共享交叉平面注意力的新型三维感知Transformer，学习不同平面间的跨平面关系，并将通用三维知识与专用三维特征进行聚合；3) 此外，设计三维感知编解码器以增强编码三平面中的通用三维知识，从而处理复杂外观类别。在ShapeNet与OmniObject3D（涵盖200余类真实世界物体）上的大量实验令人信服地表明，单模型DiffTF在保持大多样性、丰富语义与高质量的同时，实现了最先进的大词汇量三维对象生成性能。