Artistic authoring of 3D environments is a laborious enterprise that also requires skilled content creators. There have been impressive improvements in using machine learning to address different aspects of generating 3D content, such as generating meshes, arranging geometry, synthesizing textures, etc. In this paper we develop a model to generate Bidirectional Reflectance Distribution Functions (BRDFs) from descriptive textual prompts. BRDFs are four dimensional probability distributions that characterize the interaction of light with surface materials. They are either represented parametrically, or by tabulating the probability density associated with every pair of incident and outgoing angles. The former lends itself to artistic editing while the latter is used when measuring the appearance of real materials. Numerous works have focused on hypothesizing BRDF models from images of materials. We learn a mapping from textual descriptions of materials to parametric BRDFs. Our model is first trained using a semi-supervised approach before being tuned via an unsupervised scheme. Although our model is general, in this paper we specifically generate parameters for MDL materials, conditioned on natural language descriptions, within NVIDIA's Omniverse platform. This enables use cases such as real-time text prompts to change materials of objects in 3D environments such as "dull plastic" or "shiny iron". Since the output of our model is a parametric BRDF, rather than an image of the material, it may be used to render materials using any shape under arbitrarily specified viewing and lighting conditions.

翻译：三维环境的艺术创作是一项需要熟练内容创作者的艰巨任务。近年来，机器学习在三维内容生成的不同方面取得了显著进展，例如网格生成、几何布局和纹理合成等。本文开发了一种模型，能够从描述性文本提示中生成双向反射分布函数（BRDF）。BRDF是描述光线与表面材料相互作用的四维概率分布，既可通过参数化表示，也可通过枚举每个入射角和出射角对应的概率密度表格化表示。前者便于艺术编辑，后者则用于测量真实材料的外观。已有大量研究致力于从材料图像中推测BRDF模型。我们学习了从材料文本描述到参数化BRDF的映射。该模型首先通过半监督方法训练，再通过无监督方案进行调优。尽管模型具有通用性，但本文特别针对NVIDIA Omniverse平台中的MDL材料，基于自然语言描述生成其参数。这使得用户可以通过实时文本提示（例如“哑光塑料”或“亮面铁”）改变三维环境中物体的材质。由于模型输出的是参数化BRDF而非材料图像，因此该模型可支持在任意指定的视角和光照条件下，使用任意形状渲染材料。