Low-Resolution BVH Traversal for Lower Ray Tracing Cost
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Solution Overview
Problem
Current ray traversal techniques in graphics processing are costly and inefficient, necessitating improved methods to reduce computational complexity.
Innovation Solution
The implementation of a low-resolution bounding volume hierarchy (BVH) that includes conservative candidate nodes associated with full-resolution BVH nodes, allowing for efficient traversal by determining intersections with primitive leaves and internal nodes, thereby reducing the number of traversals required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-resolution BVH traversal is performed, then ray tracing accuracy is maintained, but computational cost increases
Solution Approach 1:
The patent segments the BVH traversal process into two distinct phases: a low-resolution BVH for initial ray intersection testing and a full-resolution BVH for detailed processing. This segmentation allows the system to perform coarse-level culling efficiently while maintaining the option to traverse the full-resolution structure when necessary, thereby reducing overall computational cost while preserving accuracy.
Solution Approach 2:
The patent applies partial action by using a low-resolution BVH that contains only a subset of the full-resolution BVH nodes (specifically, only internal nodes and selected leaf nodes). This partial structure provides sufficient bounding volume information for ray intersection determination without requiring traversal of all nodes, thus reducing computational effort while maintaining adequate precision for the intended application.
2Productivity
If low-resolution BVH is used, then computational cost is reduced, but bounding volume information may be lost
Solution Approach 1:
The patent introduces an intermediary mapping structure that links low-resolution BVH nodes to their corresponding full-resolution BVH nodes. This intermediary mechanism ensures that when a ray intersects a conservative candidate node in the low-resolution BVH, the system can accurately retrieve and process the corresponding full-resolution node information, thereby preventing loss of bounding volume information while maintaining computational efficiency.
Solution Approach 2:
The patent employs conservative candidate nodes in the low-resolution BVH that are designed to be slightly larger than their full-resolution counterparts. This beforehand cushioning ensures that all primitive leaves are contained within the conservative candidate node bounding volumes, providing a safety margin that prevents any loss of geometric information during the downsampling process.
3Ease of operation
If conservative candidate nodes are used, then ray intersection determination is simplified, but traversal path may increase
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing the mapping between low-resolution and full-resolution BVH nodes during BVH construction. This preliminary setup allows the traversal process to quickly navigate from low-resolution to full-resolution structures without performing complex computations during ray tracing, thus simplifying intersection determination while minimizing the time penalty of extended traversal paths.
Data Source
AI summary
This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for traversing a low-resolution BVH. A processor may obtain a first indication of a low-resolution BVH that includes a set of conservative candidate nodes that are associated with corresponding internal nodes of a full-resolution BVH. The processor may traverse the low-resolution BVH by (a) determining whether a ray intersects a primitive leaf of a conservative candidate node of the set of conservative candidate nodes in response to a first determination that the ray intersects the conservative candidate node and (b) traversing an internal node of the full-resolution BVH that corresponds with the conservative candidate node in response to a second determination that the ray does not intersect the primitive leaf. The processor may output a second indication of a ray trace hit or a ray trace miss based the traversal.