Sheared Bounding Box Selection for Real-Time Ray Tracing
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Solution Overview
Problem
Current ray tracing methods rely on axis-aligned bounding boxes, which do not closely fit scene geometry, making sheared boxes inefficient for real-time rendering due to the lack of an effective method to determine the best shear configuration.
Innovation Solution
Perform eigendecomposition on geometry to obtain eigenvectors, select a shear matrix based on alignment criteria, and compute a sheared box using the selected matrix, optimizing the fitting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If axis aligned bounding boxes are used for ray intersection testing, then ray tracing speed is improved, but the bounding box does not closely fit the scene geometry
Solution Approach 1:
The patent changes the parameters of the bounding box by introducing shear transformations to the traditional axis-aligned bounding box. This creates sheared bounding boxes that can tilt and rotate to better fit the geometry while maintaining the computational efficiency of bounding box intersection testing. The shear factors are modified based on the covariance matrix of the geometry points.
Solution Approach 2:
The patent makes the bounding box dynamic by allowing it to adapt its orientation based on the geometry it encloses. Instead of being fixed to the coordinate axes, the bounding box can be sheared to match the principal components of the geometry, enabling it to dynamically adjust to different shapes and orientations.
2Manufacturing precision
If sheared boxes are used to better fit scene geometry, then bounding box fit to geometry is improved, but computation time increases due to the need to select from over one thousand possible shear configurations
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing the covariance matrix of the geometry points before ray tracing. This covariance matrix is then used to determine the optimal shear factors without needing to test all possible shear configurations during the actual rendering process, significantly reducing computation time.
Solution Approach 2:
The patent extracts the essential information needed for shear configuration selection from the covariance matrix of the geometry. By taking out the principal components from the covariance matrix, the system can directly determine the optimal shear factors without exhaustive search through all possible shear configurations.
3Manufacturing precision
If sheared boxes are used to improve geometry fitting, then bounding box fit to geometry is improved, but device complexity increases due to the need for eigendecomposition and shear matrix selection
Solution Approach 1:
The patent replaces complex mechanical systems with simpler mathematical operations. Instead of using complex iterative optimization or brute-force search through shear configurations, the system uses eigendecomposition of the covariance matrix, which is a well-established and efficient mathematical technique that simplifies the selection process.
Data Source
AI summary
Ray tracing simulates how light interacts with objects in a scene to render realistic images. In many ray tracing solutions, a bounding volume around a geometry in the scene is computed and a ray intersection with the bounding volume is tested. For a ray that does not intersect the bounding volume, tracing of the ray can be skipped for points within the bounding volume, thereby saving significant processing time and accelerating the ray tracing performed for a given scene. Most current ray-object intersection tests rely on use of axis-aligned bounding boxes, which do not usually fit closely to the actual geometry in the scene. However, using sheared boxes is computationally inefficient and not feasible for use with real-time rendering. The present disclosure provides fast sheared box computations for scene geometry, which can better fit the box to the scene geometry while still being computed efficiently to allow for real-time rendering.