  Denoising diffusion models have demonstrated outstanding results in 2D image
generation, yet it remains a challenge to replicate its success in 3D shape
generation. In this paper, we propose leveraging multi-view depth, which
represents complex 3D shapes in a 2D data format that is easy to denoise. We
pair this representation with a diffusion model, MVDD, that is capable of
generating high-quality dense point clouds with 20K+ points with fine-grained
details. To enforce 3D consistency in multi-view depth, we introduce an
epipolar line segment attention that conditions the denoising step for a view
on its neighboring views. Additionally, a depth fusion module is incorporated
into diffusion steps to further ensure the alignment of depth maps. When
augmented with surface reconstruction, MVDD can also produce high-quality 3D
meshes. Furthermore, MVDD stands out in other tasks such as depth completion,
and can serve as a 3D prior, significantly boosting many downstream tasks, such
as GAN inversion. State-of-the-art results from extensive experiments
demonstrate MVDD's excellent ability in 3D shape generation, depth completion,
and its potential as a 3D prior for downstream tasks.
