Tessellation With Displacement Factors for Smooth Level-of-Detail Transitions
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Solution Overview
Problem
Existing tessellation methods in computer graphics suffer from visual artefacts such as popping and swimming when changing levels of detail, particularly when using displacement mapping, due to abrupt changes in vertex parameters and vertex formation.
Innovation Solution
A tessellation method that uses vertex tessellation factors and displacement factors to add new vertices and modify world space parameters smoothly, ensuring gradual changes in vertex parameters by interpolating between parent and target values using displacement factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of primitives is increased to improve tessellation accuracy, then the approximation quality improves, but the processing effort required to render the scene increases
Solution Approach 1:
The patent implements dynamic tessellation where the level of detail is adjusted based on view distance and importance. The system automatically increases primitive count for close-up or important objects while maintaining lower counts for distant objects, optimizing the balance between accuracy and rendering performance through real-time parameter adjustment
2Productivity
If vertex parameters change abruptly during tessellation level transitions, then the tessellation can be computed efficiently, but visual artefacts such as popping and swimming occur
Solution Approach 1:
The patent pre-calculates and stores vertex parameters for multiple tessellation levels in advance. When transitioning between detail levels, the system smoothly interpolates between pre-computed parameter sets rather than performing abrupt changes, preventing visual artefacts while maintaining computational efficiency
Solution Approach 2:
The system uses displacement factors to gradually adjust vertex parameters during tessellation level transitions. By modifying parameters incrementally through interpolation rather than abruptly changing them, the patent maintains visual continuity while enabling efficient level-of-detail transitions
Data Source
AI summary
A tessellation method uses both vertex tessellation factors and displacement factors defined for each vertex of a patch, which may be a quad, a triangle or an isoline. The method is implemented in a computer graphics system and involves calculating a vertex tessellation factor for each corner vertex in one or more input patches. Tessellation is then performed on the plurality of input patches using the vertex tessellation factors. The tessellation operation involves adding one or more new vertices and calculating a displacement factor for each newly added vertex. A world space parameter for each vertex is subsequently determined by calculating a target world space parameter for each vertex and then modifying the target world space parameter for a vertex using the displacement factor for that vertex.