Ray Tracing Intersection Offsets for Watertight Primitive Selection

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Solution Overview

Problem

Existing ray tracing systems face issues with rendering artefacts due to non-deterministic rendering and errors in intersection selection, particularly when intersection distances are equal or when objects are represented with shared vertices, leading to visible holes or color inconsistencies.

Innovation Solution

Implement a method for intersection testing in ray tracing systems that uses offset intersection distances based on the orientation of primitives, comparing these offsets to select the correct intersection, ensuring non-redundant watertightness and reducing errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard intersection testing is used with shared vertices, then rendering performance is maintained, but rendering artefacts occur due to non-deterministic selection and visible holes

Engineering Contradiction:

Improverendering consistencyVSAvoidrendering artefacts

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies feedback by using the intersection distance information to determine the orientation of primitives and then using this orientation information to adjust the intersection distance comparison. This creates a feedback loop where the initial intersection test results feed back into the orientation determination, which then feeds back into the final intersection selection, ensuring consistent and deterministic results that eliminate rendering artefacts.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter used for intersection comparison from raw intersection distance to offset intersection distance. The offset is calculated based on the orientation of the primitive (front-facing or back-facing), which modifies the comparison parameter to resolve ambiguities in shared vertex intersections. This parameter transformation ensures that intersections at the same distance are resolved consistently, eliminating non-deterministic rendering behavior.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If intersection distances are compared directly, then computation is simple, but errors occur in selection when distances are equal or nearly equal

Engineering Contradiction:

Improveintersection selection accuracyVSAvoidintersection testing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the intersection distance parameter into an offset intersection distance parameter. The offset is derived from the primitive orientation (front-facing or back-facing status), which modifies the distance comparison to account for geometric ambiguities. This parameter transformation enhances measurement precision by ensuring that intersections at the same distance are differentiated based on their geometric orientation, eliminating selection errors.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent adds an additional dimension to the intersection comparison by incorporating orientation information into the distance comparison. Instead of comparing only scalar distances, the system compares offset distances that incorporate orientational data. This dimensional expansion resolves ambiguities in near-equal or equal distance intersections by introducing a new comparison criterion based on primitive orientation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Quantity of substance

If primitives share vertices to reduce geometry data, then memory usage decreases, but rendering artefacts appear due to ambiguous intersections

Engineering Contradiction:

Improvegeometry data volumeVSAvoidintersection determination reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses feedback from the intersection testing process to determine primitive orientation, which then feeds back into the intersection distance comparison. This feedback mechanism ensures that shared vertex intersections are resolved consistently by using the orientation information obtained during the intersection test itself to guide the final selection, maintaining reliability despite reduced geometry data.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the comparison parameter from raw intersection distance to offset intersection distance, where the offset is based on primitive orientation. This parameter transformation allows the system to handle shared vertex intersections reliably by using orientational information to disambiguate intersections at the same distance, maintaining rendering quality with reduced geometry data.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260065576A1Intersection Testing in a Ray Tracing System Using Offset Intersection Distances

Publication Date: 2026.03.05 IMAGINATION TECH LTD

AI summary

A method and an intersection testing module for performing intersection testing in a ray tracing system determines a first offset intersection distance which is equal to a sum of an intersection distance at which a ray intersects a first primitive and a first offset which is dependent upon the orientation of the first primitive. A second offset intersection distance is determined which is equal to a sum of an intersection distance at which the ray intersects a second primitive and a second offset which is dependent upon the orientation of the second primitive. The determined first and second offset intersection distances are compared to select the intersection of the ray with one of the first and second primitives.