Recovering the intrinsic physical attributes of a scene from images, generally termed as the inverse rendering problem, has been a central and challenging task in computer vision and computer graphics. In this paper, we present GUS-IR, a novel framework designed to address the inverse rendering problem for complicated scenes featuring rough and glossy surfaces. This paper starts by analyzing and comparing two prominent shading techniques popularly used for inverse rendering, forward shading and deferred shading, effectiveness in handling complex materials. More importantly, we propose a unified shading solution that combines the advantages of both techniques for better decomposition. In addition, we analyze the normal modeling in 3D Gaussian Splatting (3DGS) and utilize the shortest axis as normal for each particle in GUS-IR, along with a depth-related regularization, resulting in improved geometric representation and better shape reconstruction. Furthermore, we enhance the probe-based baking scheme proposed by GS-IR to achieve more accurate ambient occlusion modeling to better handle indirect illumination. Extensive experiments have demonstrated the superior performance of GUS-IR in achieving precise intrinsic decomposition and geometric representation, supporting many downstream tasks (such as relighting, retouching) in computer vision, graphics, and extended reality.

本文提出的GUS-IR框架解决了逆向渲染中复杂场景（如粗糙和光滑表面）的物理属性重建问题。通过综合前向阴影和延迟阴影的优点，本文提供了一种统一的阴影解决方案，同时改善了几何表示和形状重建。实验结果表明，GUS-IR在内在分解和几何表示方面表现优越，支持计算机视觉、图形学和扩展现实中的多种后续任务。

GUS-IR：用于逆向渲染的统一阴影高斯散射