Assisting people in efficiently producing visually plausible 3D characters has always been a fundamental research topic in computer vision and computer graphics. Recent learning-based approaches have achieved unprecedented accuracy and efficiency in the area of 3D real human digitization. However, none of the prior works focus on modeling 3D biped cartoon characters, which are also in great demand in gaming and filming. In this paper, we introduce 3DBiCar, the first large-scale dataset of 3D biped cartoon characters, and RaBit, the corresponding parametric model. Our dataset contains 1,500 topologically consistent high-quality 3D textured models which are manually crafted by professional artists. Built upon the data, RaBit is thus designed with a SMPL-like linear blend shape model and a StyleGAN-based neural UV-texture generator, simultaneously expressing the shape, pose, and texture. To demonstrate the practicality of 3DBiCar and RaBit, various applications are conducted, including single-view reconstruction, sketch-based modeling, and 3D cartoon animation. For the single-view reconstruction setting, we find a straightforward global mapping from input images to the output UV-based texture maps tends to lose detailed appearances of some local parts (e.g., nose, ears). Thus, a part-sensitive texture reasoner is adopted to make all important local areas perceived. Experiments further demonstrate the effectiveness of our method both qualitatively and quantitatively. 3DBiCar and RaBit are available at gaplab.cuhk.edu.cn/projects/RaBit.

翻译：帮助人们高效地生成视觉上逼真的三维角色一直是计算机视觉与计算机图形学领域的基础研究课题。近年来，基于学习的方法在三维真实人体数字化方面取得了前所未有的精度和效率。然而，此前尚无任何工作聚焦于三维双足卡通角色建模，而这类角色在游戏和影视领域需求巨大。本文首次提出了大规模三维双足卡通角色数据集3DBiCar，以及对应的参数化模型RaBit。该数据集包含1,500个由专业艺术家手工制作的拓扑一致的高质量三维带纹理模型。基于此数据，RaBit被设计为具有类似SMPL的线性混合形状模型和基于StyleGAN的神经UV纹理生成器，可同时表达形状、姿态和纹理。为证明3DBiCar与RaBit的实用性，我们开展了多种应用，包括单视角重建、基于草图的建模和三维卡通动画。在单视角重建场景中，我们发现从输入图像到输出UV纹理图的直接全局映射容易丢失局部区域（如鼻子、耳朵）的细节外观。因此，采用了一种对局部区域敏感的纹理推理器，使所有重要局部区域均能被感知。实验从定性和定量两方面进一步证明了我们方法的有效性。3DBiCar与RaBit可在gaplab.cuhk.edu.cn/projects/RaBit获取。