Ray-Object Intersection Testing with Contained Region Culling
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Solution Overview
Problem
Existing ray tracing systems face inefficiencies in intersection testing, particularly when using acceleration structures, as they often require extensive computations to determine if a ray intersects with an object, especially in complex scenes with many primitives, and parallel traversal algorithms waste resources testing occluded nodes.
Innovation Solution
The method involves determining if a ray intersects with a bounding region of an object partitioning hierarchy, allowing for conservative hit testing without traversing to leaf nodes, thereby reducing the need for triangle tests and optimizing intersection testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional ray tracing systems use acceleration structures with hierarchical nodes to reduce intersection tests, then the number of intersection tests is reduced, but parallel traversal algorithms still waste resources testing occluded nodes
Solution Approach 1:
The patent applies preliminary action by introducing a contained region test that can be performed before traversing down the acceleration structure hierarchy. By testing whether a ray intersects the contained region of a node first, the system can determine early whether further traversal is necessary, preventing wasted computation on occluded nodes before they are tested
Solution Approach 2:
The contained region acts as an intermediary between the bounding region and the leaf nodes. This intermediate structure provides a conservative test that can eliminate entire subtrees of the acceleration structure without requiring full traversal, thereby reducing both the number of intersection tests and the computational resources wasted on occluded nodes
2Measurement precision
If the system traverses to leaf nodes to perform triangle tests for accurate intersection detection, then intersection testing accuracy is improved, but computational complexity and time increase significantly
Solution Approach 1:
The patent applies partial action by performing only the necessary contained region test when using conservative hit testing mode, rather than always traversing to leaf nodes for full triangle tests. This partial testing approach maintains sufficient accuracy for shadow ray determination while significantly reducing computational time
Solution Approach 2:
The patent segments the intersection testing process into two distinct phases: a conservative hit testing phase using contained regions for rapid determination, and an optional precise intersection phase using leaf node traversal. This segmentation allows the system to choose the appropriate level of precision based on the specific rendering requirements
Data Source
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AI summary
Object intersection testing in a ray tracing system. There is provided a method of determining, in a ray tracing system, whether a ray intersects an object of a scene, wherein the object is contained within a bounding region that is finite and forms part of an object partitioning hierarchy. The method comprising: determining that the ray intersects the bounding region; obtaining at least one contained region, wherein each at least one contained region is contained within, and smaller than, extents of a geometry defined by the object; determining that the ray intersects a contained region of the at least one contained region; and determining whether the ray intersects the object in dependence on at least determining that the ray intersects the contained region.