Inverse Rendering of Glossy Objects via the Neural Plenoptic Function and Radiance Fields
Authors: Haoyuan Wang, Wenbo Hu, Lei Zhu, Rynson W.H. Lau

Inverse rendering aims at recovering both geometry and materials of objects. It provides a more compatible reconstruction for conventional rendering engines compared with the neural radiance fields (NeRFs). On the other hand existing NeRF-based inverse rendering methods cannot handle glossy objects with local light interactions well as they typically oversimplify the illumination as a 2D environmental map which assumes infinite lights only. Observing the superiority of NeRFs in recovering radiance fields we propose a novel 5D Neural Plenoptic Function (NeP) based on NeRFs and ray tracing such that more accurate lighting-object interactions can be formulated via the rendering equation. We also design a material-aware cone sampling strategy to efficiently integrate lights inside the BRDF lobes with the help of pre-filtered radiance fields. Our method has two stages: the geometry of the target object and the pre-filtered environmental radiance fields are reconstructed in the first stage and materials of the target object are estimated in the second stage with the proposed NeP and material-aware cone sampling strategy. Extensive experiments on the proposed real-world and synthetic datasets demonstrate that our method can reconstruct high-fidelity geometry/materials of challenging glossy objects with complex lighting interactions from nearby objects. Project webpage: https://whyy.site/paper/nep