Ray-Coordinate Intersection Testing for Low-Latency Ray Tracing
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Solution Overview
Problem
Ray tracing systems face challenges in reducing power consumption, hardware requirements, and latency due to computationally intensive intersection testing, particularly in hardware implementations.
Innovation Solution
Perform intersection testing in a ray tracing system using a ray coordinate system with two non-parallel axes orthogonal to the ray direction, determining intersection attributes and their changes in these axes to process intersections efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex floating-point arithmetic is used for intersection testing, then measurement precision is improved, but use of energy and device complexity increase
Solution Approach 1:
The patent segments the intersection testing process into multiple stages: coarse culling using simplified bounding volume tests, followed by refined intersection testing only for promising candidates. This segmentation allows the system to use low-precision arithmetic for most rays and reserve high-precision floating-point arithmetic only for critical intersection tests, significantly reducing overall power consumption while maintaining rendering quality.
Solution Approach 2:
The patent applies partial precision arithmetic by using lower-precision fixed-point or integer arithmetic for preliminary intersection tests and culling operations, then transitions to full floating-point precision only when necessary for final intersection determination. This partial application of high-precision arithmetic reduces energy consumption while maintaining sufficient measurement precision for visual rendering.
2Measurement precision
If complex floating-point arithmetic is used for intersection testing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the ray tracing pipeline into distinct hardware units: a culling unit using simplified arithmetic for broad-phase intersection tests, and a detailed intersection unit using floating-point arithmetic only for narrow-phase tests. This segmentation allows the system to achieve high measurement precision where needed while keeping the majority of the hardware relatively simple.
Solution Approach 2:
The patent introduces an intermediary data structure and coordinate system transformation that simplifies the intersection testing problem. By transforming ray and primitive representations into a standardized form with pre-computed parameters, the patent reduces the complexity of floating-point arithmetic operations required, making the hardware implementation more manageable.
3Measurement precision
If complex floating-point arithmetic is used for intersection testing, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary computations of ray parameters, primitive bounding volumes, and transformation matrices before the actual intersection testing. By pre-computing these values with high precision and storing them in optimized data structures, the patent enables faster intersection tests that require fewer floating-point operations during the critical rendering path, thus improving productivity while maintaining precision.
Solution Approach 2:
The patent segments intersection testing into a fast coarse culling phase using pre-computed bounding volumes and a slower detailed intersection phase using full precision arithmetic. This segmentation allows the system to quickly eliminate non-intersecting rays without paying the full precision cost, thereby improving overall rendering throughput while maintaining measurement precision for actual intersections.
Data Source
AI summary
Intersection testing in a ray tracing system is performed for a ray with respect to a primitive. An intersection attribute value is determined for a primary sample of the ray relating to an intersection between the ray and the primitive in a ray coordinate system. The ray coordinate system has two non-parallel axes that are both transverse to the direction of the ray, and an origin of the ray coordinate system is on the ray. For one or both of the two non-parallel axes of the ray coordinate system, data is determined indicating a change to the intersection attributes in a direction parallel to that axis. The intersection between the ray and the primitive is processed using the determined value of the intersection attributes for the primary sample of the ray and the determined data indicating a change to the intersection attributes in the directions parallel to the two non-parallel axes.