Particle-based representations of radiance fields such as 3D Gaussian Splatting have found great success for reconstructing and re-rendering of complex scenes. Most existing methods render particles via rasterization, projecting them to screen space tiles for processing in a sorted order. This work instead considers ray tracing the particles, building a bounding volume hierarchy and casting a ray for each pixel using high-performance GPU ray tracing hardware. To efficiently handle large numbers of semi-transparent particles, we describe a specialized rendering algorithm which encapsulates particles with bounding meshes to leverage fast ray-triangle intersections, and shades batches of intersections in depth-order. The benefits of ray tracing are well-known in computer graphics: processing incoherent rays for secondary lighting effects such as shadows and reflections, rendering from highly-distorted cameras common in robotics, stochastically sampling rays, and more. With our renderer, this flexibility comes at little cost compared to rasterization. Experiments demonstrate the speed and accuracy of our approach, as well as several applications in computer graphics and vision. We further propose related improvements to the basic Gaussian representation, including a simple use of generalized kernel functions which significantly reduces particle hit counts.

翻译：基于粒子的辐射场表示方法（如三维高斯泼溅）在复杂场景的重建与重渲染方面取得了巨大成功。现有方法大多通过光栅化渲染粒子，将其投影到屏幕空间分块中并按排序顺序处理。本研究则采用光线追踪粒子方案，构建包围体层次结构，并利用高性能GPU光线追踪硬件为每个像素投射光线。为高效处理大量半透明粒子，我们提出一种专用渲染算法：通过包围网格封装粒子以利用快速光线-三角形相交检测，并按深度顺序对相交批次进行着色。光线追踪的优势在计算机图形学中广为人知：可处理非相干光线以实现阴影与反射等次级光照效果，支持机器人学中常见的高度畸变相机渲染，实现光线随机采样等。我们的渲染器在保持这种灵活性的同时，其性能成本与光栅化方法相当。实验验证了本方法的速度与精度，并展示了在计算机图形学与视觉领域的多个应用案例。我们进一步对基础高斯表示提出相关改进，包括采用广义核函数的简易方案，该方案显著降低了粒子命中次数。