Inverse Rendering of Glossy Objects via the Neural Plenoptic Function and Radiance Fields

Inverse rendering, aiming at recovering both the geometry and materials of objects, provides a more compatible reconstruction to conventional rendering engines compared with the popular neural radiance fields (NeRFs). However, existing NeRF-based inverse rendering methods cannot handle glossy objects with local light interactions well, as these methods 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 assistance of pre-filtered radiance fields. Our method is divided into 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 both high-fidelity geometry and materials of challenging glossy objects with complex lighting interactions from nearby objects. We will release the code and dataset.