Ray Tracing Intersection Testing for Deterministic Shared-Edge Rendering
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Solution Overview
Problem
Existing ray tracing systems face issues with non-deterministic rendering due to equal intersection distances and rendering artefacts like 'Z fighting' and visible holes in meshes, particularly when dealing with shared edges and vertices, leading to perceptual quality degradation.
Innovation Solution
Implement a method for intersection testing in ray tracing systems that considers the orientation of primitives and uses a threshold to select the correct intersection based on orientation differences, ensuring non-redundant watertightness and reducing rendering artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intersection testing is used without orientation consideration, then the number of intersection tests is reduced through acceleration structures, but rendering becomes non-deterministic and produces artefacts like Z fighting and visible holes
Solution Approach 1:
The patent introduces a new parameter (orientation) to the intersection testing process. By considering the orientation of primitives in addition to intersection distance, the system can disambiguate between multiple intersections at the same distance, ensuring deterministic and accurate rendering results.
2Ease of manufacture
If primitives share edges and vertices, then geometric efficiency is improved, but equal intersection distances occur leading to non-deterministic rendering
Solution Approach 1:
The patent introduces asymmetry through orientation-based differentiation. Even though primitives share edges and vertices symmetrically, the orientation parameter creates an asymmetric distinction that allows the system to consistently determine which primitive should be rendered first, eliminating non-deterministic behavior.
3Device complexity
If intersection distance alone is used for selecting intersections, then the selection process is simple, but rendering artefacts like Z fighting occur
Solution Approach 1:
The patent introduces orientation as an intermediary parameter that mediates between intersection distance and final selection decision. This intermediary helps resolve ambiguities in the selection process and eliminates rendering artefacts without significantly increasing overall system complexity.
Data Source
AI summary
A method and an intersection testing module for performing intersection testing in a ray tracing system determines that a difference between an intersection distance at which a ray intersects a first primitive and an intersection distance at which the ray intersects a second primitive satisfies a comparison condition with respect to a threshold. It is determined that the orientations of the first and second primitives are different. The intersection of the ray with one of the first and second primitives is selected on the basis that the one of the first and second primitives has a particular orientation.