Ray-Box Intersection Testing Using Scaled Ray Components
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Solution Overview
Problem
Existing ray tracing systems face inefficiencies in performing intersection tests due to the large number of computations required, particularly when using acceleration structures, which can be improved by optimizing hardware implementations for intersection testing.
Innovation Solution
A method and module for determining whether a ray intersects a three-dimensional axis-aligned box by using scaled ray components and cross-multiplication values to efficiently identify intersection points without computing distances, implemented in dedicated hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional intersection testing methods are used in ray tracing systems, then comprehensive intersection detection can be achieved, but computational latency and power consumption increase significantly
Solution Approach 1:
The patent segments the intersection testing process into two distinct phases: a fast rejection phase using scaled ray components and cross-multiplication values to quickly eliminate non-intersecting rays, and a detailed intersection calculation phase only for rays that pass the rejection test. This segmentation allows the system to maintain high detection accuracy while significantly reducing computational latency for the majority of rays that do not intersect the bounding box.
Solution Approach 2:
The patent replaces traditional floating-point distance computation mechanisms with an alternative mathematical approach using scaled ray components and cross-multiplication values. This substitution eliminates the need for computationally expensive square root operations and distance calculations, achieving the same intersection detection goal with significantly reduced computational latency and power consumption.
2Measurement precision
If traditional intersection testing methods are used, then accurate intersection points can be determined, but power consumption increases
Solution Approach 1:
The patent substitutes traditional floating-point arithmetic operations with integer-based cross-multiplication calculations. This replacement eliminates power-intensive operations such as square roots and divisions, maintaining intersection point accuracy through the mathematical equivalence of the cross-multiplication method while dramatically reducing power consumption in the ray tracing system.
Solution Approach 2:
The patent divides the computational workload into a low-power rejection stage using scaled components and a high-precision calculation stage only for intersecting rays. This segmentation ensures that power consumption is minimized for the majority of non-intersecting rays while maintaining accurate intersection point determination only when necessary.
3Reliability
If comprehensive intersection testing is performed for all rays, then all potential intersections are detected, but computational effort increases
Solution Approach 1:
The patent segments intersection testing into a rapid rejection phase using scaled ray components and cross-multiplication values, followed by detailed intersection processing only for rays that pass the rejection test. This ensures that all potential intersections are detected (maintaining reliability) while significantly reducing the computational effort required for the majority of rays that do not intersect the bounding box, thereby improving rendering speed.
Solution Approach 2:
The patent performs a simplified intersection test (cross-multiplication based) that is less computationally intensive than full intersection calculation, applying this partial action to all rays to quickly identify and eliminate non-intersecting cases. This allows the system to maintain complete intersection detection reliability while improving overall productivity by reducing the computational burden on non-intersecting rays.
Data Source
AI summary
A method and intersection testing module are provided in a ray tracing system for determining whether a ray intersects a 3D axis-aligned volume. The volume is defined by a front-facing plane and a back-facing plane for each of the dimensions of the three-dimensional axis-aligned volume. Scaled ray components are determined, wherein a third scaled ray component equals 1. A scaled minimum culling distance and a scaled maximum culling distance are determined. Determined cross-multiplication values are used to identify which of the front-facing planes intersects the ray furthest along the ray and identify which of the back-facing planes intersects the ray least far along the ray. It is determined whether the ray intersects the identified front-facing plane of the volume at a position that is no further along the ray than the position at which the ray intersects the identified back-facing plane.