Rendering and reconstruction are long-standing topics in computer vision and graphics. Achieving both high rendering quality and accurate geometry is a challenge. Recent advancements in 3D Gaussian Splatting (3DGS) have enabled high-fidelity novel view synthesis at real-time speeds. However, the noisy and discrete nature of 3D Gaussian primitives hinders accurate surface estimation. Previous attempts to regularize 3D Gaussian normals often degrade rendering quality due to the fundamental disconnect between normal vectors and the rendering pipeline in 3DGS-based methods. Therefore, we introduce Normal-GS, a novel approach that integrates normal vectors into the 3DGS rendering pipeline. The core idea is to model the interaction between normals and incident lighting using the physically-based rendering equation. Our approach re-parameterizes surface colors as the product of normals and a designed Integrated Directional Illumination Vector (IDIV). To optimize memory usage and simplify optimization, we employ an anchor-based 3DGS to implicitly encode locally-shared IDIVs. Additionally, Normal-GS leverages optimized normals and Integrated Directional Encoding (IDE) to accurately model specular effects, enhancing both rendering quality and surface normal precision. Extensive experiments demonstrate that Normal-GS achieves near state-of-the-art visual quality while obtaining accurate surface normals and preserving real-time rendering performance.
渲染和重建是计算机视觉和图形学中的长期研究课题，实现高渲染质量和准确几何形状的结合是一大挑战。最近，三维高斯喷涂 (3D Gaussian Splatting, 3DGS) 的进展使得在实时速度下实现高保真新视图合成成为可能。然而，3D 高斯基元的噪声和离散特性阻碍了精确的表面估计。先前试图对 3D 高斯法向量进行正则化的方法通常因法向量与 3DGS 渲染管道之间的根本脱节而导致渲染质量下降。因此，我们提出了 Normal-GS，一种将法向量集成到 3DGS 渲染管道中的新方法。 核心思想是利用基于物理的渲染方程来建模法向量与入射光之间的交互。我们通过重新参数化表面颜色，将其表示为法向量与设计的集成方向光矢量 (Integrated Directional Illumination Vector, IDIV) 的乘积。为了优化内存使用并简化优化过程，我们采用基于锚点的 3DGS 以隐式编码局部共享的 IDIV。此外，Normal-GS 利用优化后的法向量和集成方向编码 (Integrated Directional Encoding, IDE) 精确建模高光效果，从而增强了渲染质量和表面法向精度。 大量实验表明，Normal-GS 实现了接近最新技术的视觉质量，同时获得了精确的表面法向量并保持了实时渲染性能。