Path-Traced Inverse Rendering with Global Illumination in 3D Gaussian Fields
2026-06-08 • Graphics
Graphics
AI summaryⓘ
The authors present a new way to recreate 3D objects and their materials using a technique called path tracing combined with 3D Gaussian fields. Unlike previous methods that rely on screen-based shortcuts and simpler lighting models, their approach fully simulates how light moves and bounces around in a scene with overlapping Gaussian shapes. This leads to more consistent and realistic images with better shadows, reflections, and lighting effects. Their method also accurately calculates gradients needed for optimization directly within the ray-tracing process, improving material recovery and rendering quality under complex lighting.
Ray tracingPath tracingInverse rendering3D Gaussian fieldsLight transportMonte Carlo integrationMaterial estimationSpherical-Gaussian environmentGlobal illuminationGradient propagation
Authors
Junke Zhu, Hao Zhang, Yutian Zhu, Ang Li, Chenxiao Hu, Meng Gai, Fei Zhu, Zhangjin Huang, Sheng Li
Abstract
Ray tracing enables 3D Gaussian fields to serve as a representation for physically based light transport. Faithful inverse rendering requires forward rendering and backward optimization to be defined within a consistent light-transport pipeline. Existing inverse rendering methods estimate G-buffers via splatting and optimize materials in screen space, tying the recovered properties to a rasterization-based pipeline. This pipeline mismatch, together with simplified rendering equations that neglect indirect illumination, often leads to inconsistent shading, visible artifacts, and inaccurate material-lighting estimation under path-traced rendering. Therefore, we propose a splatting-free path-traced inverse rendering framework for 3D Gaussian fields, where forward light transport and backward gradient propagation are defined within a unified ray-tracing pipeline. Our key idea is to define a path-space equivalent interaction model for overlapping Gaussian primitives, under which Monte-Carlo-based path tracing is unbiased for the induced light-transport integral, while pathwise gradients are replayed over the same ray-traced interactions rather than splatting-derived screen-space buffers. The framework optimizes materials and a compact Spherical-Gaussian environment under the full rendering equation with ray-traced visibility and multi-bounce light transport. Extensive experiments demonstrate competitive material inversion and improved path-traced rendering quality, producing more plausible shadows, reflections, and relighting results under global illumination.