G-NeRF: Geometry-enhanced Novel View Synthesis from Single-View Images
Authors: Zixiong Huang, Qi Chen, Libo Sun, Yifan Yang, Naizhou Wang, Qi Wu, Mingkui Tan

Novel view synthesis aims to generate new view images of a given view image collection. Recent attempts address this problem relying on 3D geometry priors (e.g. shapes sizes and positions) learned from multi-view images. However such methods encounter the following limitations: 1) they require a set of multi-view images as training data for a specific scene (e.g. face car or chair) which is often unavailable in many real-world scenarios; 2) they fail to extract the geometry priors from single-view images due to the lack of multi-view supervision. In this paper we propose a Geometry-enhanced NeRF (G-NeRF) which seeks to enhance the geometry priors by a geometry-guided multi-view synthesis approach followed by a depth-aware training. In the synthesis process inspired that existing 3D GAN models can unconditionally synthesize high-fidelity multi-view images we seek to adopt off-the-shelf 3D GAN models such as EG3D as a free source to provide geometry priors through synthesizing multi-view data. Simultaneously to further improve the geometry quality of the synthetic data we introduce a truncation method to effectively sample latent codes within 3D GAN models. To tackle the absence of multi-view supervision for single-view images we design the depth-aware training approach incorporating a depth-aware discriminator to guide geometry priors through depth maps. Experiments demonstrate the effectiveness of our method in terms of both qualitative and quantitative results.