Sparse Voxels Rasterization: Real-Time High-Fidelity Radiance Field Rendering

Our scene representation is a hybrid of primitive and volumetric model. (a) Primitive component. We explicitly allocate voxels primitives to cover different scene level-of-details under an Octree layout. Note that we do not replicate a traditional Octree data structure with parent-child pointers or linear Octree. We only keep voxels at the Octree leaf nodes without any ancestor nodes. (b) Volumetric component. Inside a voxel is a volumetric (trilinear) density field and a (constant) spherical harmonic field. We sample K points on the ray-voxel intersection segment to compute the intensity contribution from the voxel to the pixel with numerical integration. Adaptive level-of-details is crucial to scalability and quality. Sparse voxels with uniform voxel size can not scale up. We sort voxels by ray direction-dependent Morton order, which ensures correct primitive blending order with mathematical proof. Sorting by primtive centers like 3DGS can produce inaccurate rendering. The inaccura ... Read full article.