BVH Leaf Node Compression With Common Triangle Data
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Solution Overview
Problem
Ray tracing operations are computationally expensive due to the need to test rays against a large number of triangles in a scene, which can be inefficient and resource-intensive.
Innovation Solution
Implement a bounding volume hierarchy (BVH) with compressed triangle blocks that store common and unique data for groups of triangles, using techniques like common prefix deduplication, trailing zero deduplication, and geometry identifier compression to reduce data redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ray tracing tests rays against all triangles in a scene, then complete accuracy is achieved, but computational cost and time increase significantly
Solution Approach 1:
The patent segments the scene geometry into a hierarchical bounding volume structure where the scene is divided into bounding boxes, which are further divided into child bounding boxes, ultimately containing triangles at leaf nodes. This segmentation allows the ray tracing algorithm to test against bounding volumes first and only proceed to triangle intersection tests for bounding boxes that are actually intersected by the ray, significantly reducing the number of triangle tests required while maintaining complete accuracy.
2Productivity
If bounding volume hierarchy is used to reduce triangle tests, then ray tracing efficiency improves, but memory usage increases due to storing BVH structure
Solution Approach 1:
The patent implements a nested hierarchical structure where bounding boxes contain child bounding boxes, which contain grandchildren bounding boxes, and so on down to leaf nodes containing triangles. This nesting allows the BVH to be built recursively with each level providing a coarser approximation, enabling the structure to be stored more compactly by sharing common bounding box data among multiple child nodes and only storing unique differences at each level of the hierarchy.
Solution Approach 2:
The patent changes the parameter representation of bounding box data by storing only the differing parameters between parent and child bounding boxes rather than storing complete bounding box data at each level. This parameter change approach reduces memory usage by exploiting the fact that child bounding boxes are subsets of their parent bounding boxes and therefore share many common parameters, storing only the minimal necessary information to define each bounding box uniquely.
3Measurement precision
If leaf nodes store complete triangle data, then triangle reconstruction is accurate, but data redundancy increases
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing the bounding box hierarchy structure before ray tracing operations. The BVH is built in advance with all bounding box parameters calculated and stored in a compressed hierarchical format. This preliminary organization of geometry data into a structured hierarchy allows rapid traversal during ray tracing without requiring redundant storage of complete triangle data at each node, as the hierarchical structure itself encodes the spatial relationships efficiently.
Data Source
AI summary
A technique for performing ray tracing operations is provided. The technique includes identifying triangles to include in a compressed triangle block; storing data common to the identified triangles as common data of the compressed triangle block; and storing data unique to the identified triangles as unique data of the compressed triangle block.