Split BVH Instance Volumes to Reduce Ray Tracing False Positives
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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, leading to inefficiencies in graphics rendering.
Innovation Solution
Implementing a bounding volume hierarchy (BVH) with split bounding volumes that allow for better geometric fitting and reduce false positives by using instance nodes with multiple references, and applying an instance traversal limiting criterion to ensure traversal into an instance node only once during a BVH traversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bounding volume hierarchy is used to organize scene geometry, then ray tracing efficiency is improved by reducing the number of ray-triangle intersections, but false positives occur when rays intersect bounding volumes that do not contain actual geometry
Solution Approach 1:
The patent applies segmentation by dividing instance nodes into multiple split bounding volumes, where each split bounding volume corresponds to a specific spatial region. This segmentation allows the BVH to more precisely represent the actual geometry distribution, reducing false positives while maintaining traversal efficiency. The split bounding volumes are organized in a hierarchical structure that enables selective traversal based on ray-spatial relationship.
2Quantity of substance
If instance nodes with multiple references are used to represent duplicated geometry, then memory usage is reduced by avoiding duplication, but traversal complexity increases due to multiple potential traversal paths
Solution Approach 1:
The patent implements the nested doll principle by creating a hierarchical nesting structure where split bounding volumes are nested within instance nodes, which are in turn nested within the overall BVH structure. This nested organization allows multiple references to the same instance node to be managed systematically, reducing memory usage while controlling traversal complexity through the hierarchical framework.
Solution Approach 2:
The patent applies preliminary action by pre-organizing instance nodes with multiple references into a structured format with associated split bounding volumes before ray tracing begins. This preliminary organization enables efficient traversal by pre-computing spatial relationships and reference structures, reducing the complexity encountered during actual ray tracing operations.
3Device complexity
If traditional bounding volumes are used without splitting, then the BVH structure is simpler to implement, but rendering accuracy decreases due to larger bounding volumes enclosing more empty space
Solution Approach 1:
The patent applies segmentation by dividing instance nodes into multiple split bounding volumes, where each split bounding volume corresponds to a specific spatial region. This segmentation allows the BVH to more precisely represent the actual geometry distribution, reducing false positives while maintaining traversal efficiency. The split bounding volumes are organized in a hierarchical structure that enables selective traversal based on ray-spatial relationship.
Data Source
AI summary
A technique for performing ray tracing operations is provided. The technique includes detecting intersection of a ray with a split bounding volume of an instance of a bounding volume hierarchy; determining whether the split bounding volume meets an instance traversal limiting criterion; and continuing BVH traversal based on the determining.