Ray-Polygon Intersection Testing for Watertight Shared Edges
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Solution Overview
Problem
Existing ray tracing systems face challenges in efficiently performing intersection tests with convex polygons, particularly when dealing with shared vertices and edges, leading to rendering errors such as holes and non-deterministic color rendering due to redundant or missing intersection tests.
Innovation Solution
A method and module for intersection testing in a ray tracing system that projects convex polygon vertices onto axes orthogonal to the ray direction, using a vertex ordering scheme to determine intersection parameters, ensuring watertight and non-redundant results by analyzing the signs of these parameters, and employing a ray-coordinate system to optimize the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intersection testing methods are used for convex polygons with shared vertices, then rendering coverage is achieved, but rendering errors such as holes and non-deterministic color rendering occur due to redundant or missing intersection tests
Solution Approach 1:
The patent inverts the traditional approach by using a vertex ordering scheme that processes vertices in a consistent sequence (e.g., counter-clockwise) regardless of polygon definition order. This inversion of the processing logic ensures that shared vertices and edges are handled uniformly, eliminating rendering holes and non-deterministic behavior while maintaining computational efficiency through systematic parameter sign analysis.
2Reliability
If intersection tests are performed for all convex polygons including those with shared vertices, then complete scene coverage is achieved, but computational latency and power consumption increase due to redundant tests
Solution Approach 1:
The patent merges the handling of shared vertices and edges into a unified processing framework. By using a vertex ordering scheme and analyzing parameter signs systematically, the method combines multiple intersection tests into a coherent evaluation process that ensures complete scene coverage without performing redundant computations on shared geometric elements, thereby reducing computational latency and power consumption.
3Adaptability or versatility
If traditional vertex ordering based on polygon definition is used, then polygon-specific characteristics are preserved, but rendering consistency fails due to variations in vertex ordering affecting intersection results
Solution Approach 1:
The patent applies local quality by implementing a vertex ordering scheme that enforces consistent ordering (e.g., counter-clockwise) at the local level of each polygon's vertex processing. This local enforcement of ordering rules ensures that intersection parameter signs are determined consistently across all polygons, maintaining rendering determinism while preserving the flexibility of different polygon definitions through the systematic application of ordering criteria.
Data Source
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AI summary
There is provided a method and an intersection testing module in a ray tracing system for performing intersection testing for a ray with respect to a plurality of convex polygons. Each of the convex polygons is defined by an ordered set of vertices, wherein at least one of the vertices is a shared vertex which is used to define two or more of the convex polygons. The vertices of the convex polygons are projected onto a pair of axes orthogonal to the ray direction, wherein the origin of the pair of axes corresponds with the ray origin. A vertex ordering scheme defines an ordering of the projected vertices which is independent of the ordering of the vertices in the ordered sets of vertices defining the convex polygons. For each of the convex polygons, for each edge of the convex polygon defined by two of the projected vertices, a parameter indicative of which side of the edge the ray passes on is determined, wherein if the ray is determined to intersect a point on the edge then the parameter is determined based upon whether the ordering, defined by the vertex ordering scheme, of the projected vertices defining the edge matches the ordering of the vertices in the ordered set of vertices defining the convex polygon. It is determined whether the ray intersects the convex polygon based on the parameters determined for the edges of the convex polygon.