Shared BVH Structure for Ray Tracing and Collision Detection
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Solution Overview
Problem
Existing ray tracing systems face inefficiencies in both rendering and collision detection due to the high computational cost of testing every triangle in a scene, especially when using axis-aligned bounding boxes that result in false positives.
Innovation Solution
Utilizing a bounding volume hierarchy (BVH) with oriented bounding boxes for both ray tracing and collision detection, where the BVH is generated for ray tracing and reused for collision detection, reducing the need for extensive triangle testing by leveraging the spatial representation of the BVH to eliminate non-intersecting volumes early in the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If axis-aligned bounding boxes are used for ray tracing, then the implementation is simple, but false positives increase and computational efficiency decreases
Solution Approach 1:
The patent changes the orientation parameter of bounding boxes from axis-aligned to arbitrarily oriented, allowing them to better fit the underlying geometry. This parameter change reduces false positives by aligning bounding boxes with object orientations, thereby improving ray tracing efficiency without sacrificing implementation feasibility.
Solution Approach 2:
The patent employs oriented bounding boxes that can rotate and align with geometric features, analogous to adapting the shape to fit the object rather than forcing the object to fit a fixed shape. This allows tighter bounds and fewer false positives compared to rigid axis-aligned boxes.
2Reliability
If every triangle in a scene is tested for both ray tracing and collision detection, then completeness is ensured, but computational overhead increases significantly
Solution Approach 1:
The patent segments the scene into a hierarchical structure of bounding volumes (BVH), organizing triangles into nested groups. This segmentation allows the system to test bounding volumes first and only process triangles in regions that potentially intersect, dramatically reducing the number of triangle tests required for both ray tracing and collision detection while maintaining completeness.
Solution Approach 2:
The patent performs preliminary organization of scene geometry into a bounding volume hierarchy before executing ray tracing or collision detection queries. This preliminary structuring enables efficient culling of non-intersecting regions, reducing computational overhead by eliminating unnecessary triangle tests in advance.
3Reliability
If separate data structures are built for ray tracing and collision detection, then each operation is optimized, but memory usage and construction time increase
Solution Approach 1:
The patent designs a universal bounding volume hierarchy data structure that serves both ray tracing and collision detection purposes. By making the BVH multi-functional, the system eliminates the need for separate data structures, reducing memory usage and construction time while maintaining effectiveness for both operations through the common hierarchical organization of scene geometry.
4Measurement precision
If oriented bounding boxes are used instead of axis-aligned bounding boxes, then false positives are reduced, but computational complexity increases
Solution Approach 1:
The patent changes the orientation parameter of bounding boxes from fixed axis-alignment to arbitrary orientation, allowing them to better fit the underlying geometry. This parameter change improves measurement precision by reducing false positives, while the hierarchical organization and efficient algorithms keep computational complexity manageable.
Data Source
AI summary
Techniques herein propose utilization of the bounding volume hierarchy generated for ray tracing for the purposes of collision detection. In various examples, once an application has requested ray tracing operations be performed, thus resulting in building of a bounding volume hierarchy (“BVH”), the application also requests collision detection to be performed with that BVH. Such requests can be made to a driver, for example, which causes the collision detection tests to be performed using the previously generated BVH (for example, on the central processing unit (“CPU”) or on a graphics processing unit). This double use of the BVH provides efficiencies as compared with having completely separate rendering and collision detection operations.