BVH Path Encoding for Faster Ray Traversal Restarts
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Solution Overview
Problem
Existing ray tracing techniques are resource-intensive and inefficient for real-time performance, particularly in distributed systems, as they lack effective methods for handling ray-scene intersections and denoising across multiple devices.
Innovation Solution
A GPU-based ray traversal algorithm using compressed wide BVHs and octant-aware fixed-order traversal, combined with distributed denoising frameworks that maintain traversal stacks in a compressed format, enabling efficient ray traversal and denoising across multiple devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional ray traversal algorithms are used for real-time rendering, then image quality can be maintained, but computational resources and time consumption increase significantly
Solution Approach 1:
The patent segments the BVH traversal process into distinct phases: identifying candidate triangles using axis-aligned bounding boxes, performing precise triangle intersection tests only on candidates, and using spatial partitioning to divide the scene into manageable regions. This segmentation allows the system to quickly eliminate non-intersecting triangles while maintaining accurate intersection detection, resolving the contradiction between image quality and traversal time.
Solution Approach 2:
The patent performs preliminary actions by pre-computing and storing axis-aligned bounding boxes for triangles, pre-sorting triangles by their bounding box coordinates, and pre-identifying candidate triangles before performing expensive intersection tests. This preliminary preparation significantly reduces the computational burden during actual ray traversal, enabling real-time performance while maintaining accurate intersection detection for high-quality rendering.
2Measurement precision
If comprehensive ray-scene intersection tests are performed, then rendering accuracy is improved, but computational complexity and resource consumption increase
Solution Approach 1:
The patent applies local quality by using different levels of precision at different stages of the traversal process. Axis-aligned bounding box tests use simple coordinate comparisons for quick filtering, while triangle intersection tests use precise geometric calculations only for candidate triangles. This localized application of different precision levels maintains overall intersection detection accuracy while significantly reducing computational complexity.
Solution Approach 2:
The patent substitutes complex mechanical intersection testing with a two-stage system: first using simple axis-aligned bounding box coordinate comparisons to filter candidates, then applying precise triangle intersection mathematics only to the filtered set. This substitution of a simple filtering mechanism for the initial screening stage reduces computational complexity while preserving measurement precision in the final intersection detection.
3Productivity
If distributed rendering is implemented across multiple devices, then rendering capability is enhanced, but data accessibility and coordination become more difficult
Solution Approach 1:
The patent implements universality by designing a data structure and algorithm that can operate independently on any device while producing consistent results. Each device can process its assigned portion of the scene using the same BVH traversal algorithm and triangle intersection tests, ensuring that the system is multi-functional and can be distributed across any number of devices without requiring device-specific optimizations or complex coordination protocols.
Data Source
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AI summary
Apparatus and method for preventing re-traversal of a prior path on a restart. For example, one embodiment of an apparatus comprises: a ray generator to generate a plurality of rays in a first graphics scene; a bounding volume hierarchy (BVH) generator to construct a BVH comprising a plurality of hierarchically arranged nodes, wherein the BVH comprises a specified number of child nodes at a current BVH level beneath a parent node in the hierarchy; traversal/intersection circuitry to traverse one or more of the rays through the hierarchically arranged nodes of the BVH to form a current traversal path and intersect the one or more rays with primitives contained within the nodes; and traversal tracking circuitry to maintain a path encoding array to store path data related to the current traversal path, the path data comprising an index of a currently traversed child node; wherein the traversal/intersection circuitry is to prevent one or more subsequent rays from re-intersecting primitives from which they originated and/or avoid re-traversing the current traversal path based on the path data in the path encoding array.