GauTracer: Extending Ray Tracing Accelerator for Gaussian-Based Scene Representation

Gaussian splatting has emerged as a promising paradigm in 3D vision, enabling instant scene reconstruction and photorealistic rendering. However, integrating rasterization-oriented Gaussian representations into ray tracing pipelines remains challenging. Existing ray tracing accelerators (RTAs) lack native support for Gaussian primitives, forcing reliance on software shader, which incurs significant instruction overhead, thread divergence, and excessive memory traffic. To address this, we present GauTracer, a ray tracing accelerator with efficient hardware support for Gaussian primitives. GauTracer elevates Gaussians to first-class primitives via lightweight microarchitectural extensions, including a dedicated Ray-Gauss Intersection Unit (RGIU). To improve versatility, the RGIU adopts a reconfigurable design supporting both 3D ellipsoidal and 2D planar Gaussian primitives with minimal overhead. In addition, a max-heap-based Any-Gauss-Hit Unit (AGHU) maintains a per-ray hit buffer for efficient volumetric blending of Gaussian primitives. To further optimize traversal performance, GauTracer employs a treelet-based BVH traversal scheme with a far-node pruning scheme, reducing unnecessary node visits beyond the buffer's capacity. Simulation results based on Vulkan-Sim show that GauTracer achieves average performance improvements of 5.8× for 3D Gaussians and $7.3 \times$ for 2D Gaussians over the baseline GPU-RTA. It also enhances energy efficiency by $6.6 \times$ and $7.5 \times$, respectively.