Oriented Bounding Box Emulation Using Axis-Aligned Volumes
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Solution Overview
Problem
Axis-aligned bounding boxes in ray tracing do not conform well to rotated geometries, leading to increased computational costs and hardware area requirements for oriented bounding box intersection tests.
Innovation Solution
Emulate oriented bounding boxes using multiple axis-aligned bounding boxes to reduce computational overhead and hardware costs while maintaining performance benefits, by translating each oriented bounding box into N regular shapes or volumes during runtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oriented bounding boxes are used to conform to rotated geometries, then the accuracy of ray intersection tests is improved, but the computational overhead and hardware area cost increase
Solution Approach 1:
The oriented bounding box is segmented into multiple axis-aligned bounding boxes (typically 8 boxes in 3D space). Each axis-aligned bounding box represents a portion of the oriented bounding box volume. By using multiple simpler axis-aligned boxes instead of a single complex oriented box, the patent achieves accurate representation of rotated geometries while using only standard axis-aligned intersection test hardware, thus avoiding the need for dedicated oriented bounding box intersection hardware and reducing hardware area cost.
2Measurement precision
If oriented bounding boxes are used to conform to rotated geometries, then the accuracy of ray intersection tests is improved, but the computational overhead increases
Solution Approach 1:
The oriented bounding box is divided into multiple axis-aligned bounding boxes, allowing the use of efficient axis-aligned intersection tests for each segment. This segmentation approach maintains the accuracy benefits of oriented bounding boxes while leveraging the computational efficiency of axis-aligned tests, avoiding the need for expensive oriented bounding box intersection calculations.
Solution Approach 2:
Instead of performing complex oriented bounding box intersection tests, the patent creates multiple copies of simpler axis-aligned bounding boxes that collectively represent the oriented bounding box volume. The intersection test then checks the ray against these copied axis-aligned boxes, which are computationally cheaper to test while maintaining accuracy.
3Device complexity
If axis-aligned bounding boxes are used for ray tracing, then the hardware area cost is reduced, but the ability to conform to rotated geometries is worsened
Solution Approach 1:
The patent segments the oriented bounding box into multiple axis-aligned bounding boxes. This segmentation allows the use of simple axis-aligned hardware for each segment while collectively achieving accurate representation of rotated geometries. The multiple axis-aligned boxes together capture the extent of the rotated primitive without requiring complex oriented bounding box intersection hardware.
Data Source
AI summary
A technique for performing ray tracing is provided. The technique is applied to a bounding volume hierarchy which comprises a plurality of oriented bounding boxes. The oriented bounding boxes are emulated by translating each oriented bounding box into two or more volumes. After the emulating step, the bounding volume hierarchy is traversed. In some examples, the regular shapes or volumes comprise axis-aligned bounding boxes, cubes or anisotropic rectangles. In one example, the emulating step is performed at run-time using dedicated hardware.