Recently, 3D Gaussian Splatting (3DGS) has enabled photorealistic view synthesis at high inference speeds. However, its splatting-based rendering model makes several approximations to the rendering equation, reducing physical accuracy. We show that splatting and its approximations are unnecessary, even within a rasterizer; we instead volumetrically integrate 3D Gaussians directly to compute the transmittance across them analytically. We use this analytic transmittance to derive more physically-accurate alpha values than 3DGS, which can directly be used within their framework. The result is a method that more closely follows the volume rendering equation (similar to ray-tracing) while enjoying the speed benefits of rasterization. Our method represents opaque surfaces with higher accuracy and fewer points than 3DGS. This enables it to outperform 3DGS for view synthesis (measured in SSIM and LPIPS). Being volumetrically consistent also enables our method to work out of the box for tomography. We match the state-of-the-art 3DGS-based tomography method with fewer points. Being volumetrically consistent also enables our method to work out of the box for tomography. We match the state-of-the-art 3DGS-based tomography method with fewer points.

翻译：近年来，三维高斯泼溅（3DGS）技术实现了高推理速度下的逼真视图合成。然而，其基于泼溅的渲染模型对渲染方程进行了若干近似处理，降低了物理精度。我们证明，即使在光栅化器中，泼溅及其近似也是不必要的；我们转而直接对三维高斯函数进行体积积分，以解析计算其透射率。利用该解析透射率，我们推导出比3DGS物理精度更高的alpha值，这些值可直接应用于其现有框架。由此产生的方法更严格地遵循体积渲染方程（类似于光线追踪），同时保持了光栅化的速度优势。我们的方法能以比3DGS更高的精度和更少的点数表示不透明表面，从而在视图合成质量（以SSIM和LPIPS指标衡量）上超越3DGS。体积一致性还使我们的方法能直接适用于断层扫描任务，我们以更少的点数达到了当前最先进的基于3DGS的断层扫描方法的性能水平。