We present DiffHuman, a probabilistic method for photorealistic 3D human reconstruction from a single RGB image. Despite the ill-posed nature of this problem, most methods are deterministic and output a single solution, often resulting in a lack of geometric detail and blurriness in unseen or uncertain regions. In contrast, DiffHuman predicts a probability distribution over 3D reconstructions conditioned on an input 2D image, which allows us to sample multiple detailed 3D avatars that are consistent with the image. DiffHuman is implemented as a conditional diffusion model that denoises pixel-aligned 2D observations of an underlying 3D shape representation. During inference, we may sample 3D avatars by iteratively denoising 2D renders of the predicted 3D representation. Furthermore, we introduce a generator neural network that approximates rendering with considerably reduced runtime (55x speed up), resulting in a novel dual-branch diffusion framework. Our experiments show that DiffHuman can produce diverse and detailed reconstructions for the parts of the person that are unseen or uncertain in the input image, while remaining competitive with the state-of-the-art when reconstructing visible surfaces.

DiffHuman是一种基于概率的方法，通过一个单一的RGB图像实现逼真的三维人体重建。与确定性方法不同，DiffHuman根据二维图像预测三维重建的概率分布，可以生成与图像一致的多个详细的三维人体模型。此外，DiffHuman还引入了一个生成器神经网络，可以以大幅减少的运行时间进行渲染，从而实现了一种新颖的双分支扩散框架。在实验中，DiffHuman在重建可见表面方面与现有技术不相上下，并且可以对输入图像中未见或不确定的部分生成多样且详细的重建结果。

DiffHuman：人体的概率光真实三维重建