Ray tracing acceleration method based on an improved KD-Tree structure

When ray tracing is performed based on the traditional KD-Tree (K-Dimensional tree) structure, a ray may first pass through a number of leaf nodes before it intersects with one facet in the "last" leaf node. During this process, the ray needs to sequentially perform the ray-triangle intersection with all the internal facets in each of the aforementioned leaf nodes before it enters into the next leaf node, wasting a large amount of computation time. In this paper, an improved KD-Tree structure is proposed. In addition to the space occupied by a leaf node in the traditional KD-Tree, the minimum bounding box occupied by the facets of the leaf node is also introduced for the leaf node. If a ray does not intersect with the minimum bounding box when it enters into a leaf node, it will directly penetrate out of the leaf node without performing ray-triangle intersection procedure and then enter into the next leaf node. Simulation results for T-cavity and L-cavity models show that, under the parameter conditions of this paper, the total ray tracing time based on the improved KD-Tree structure is reduced by 10% to 44% compared with the traditional KD-Tree, which effectively improves the computational efficiency of the ray tracing process.