Optimization of GPU Ray Tracing Algorithm for Voxel Data Using a Tetrahexacontree Data Structure

An optimization of the traversal algorithm using tetrahexacontree data structure is presented, which improves raytracing performance in voxel scenes. In existing research on this data structure, the use of the classical 3DDDA method [1] was proposed for traversing the cells of the space partition without any additional modifications. This approach proved to be less efficient in terms of performance compared to the popular hierarchical voxel data structure—the octree [2]. The aim of this work is to justify and evaluate the application of optimization techniques to the tetrahexacontree traversal algorithm. By analyzing cell occupancy bitmaps, the ray can skip empty regions within the tree nodes, thereby reducing the number of ray steps and thus improving performance. The optimization incurs a small overhead in terms of processor time and requires a fixed amount of extra memory, but does not require any additional preprocessing of the input data. The optimization is compatible with both dense and sparse tree representations. On average, the algorithm optimization yields a 28% performance gain compared to naive tetrahexacontree traversal algorithm, and is 21% more efficient than an octree method.