Perspective Corrected Tessellation via Parameter Space Warping
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Solution Overview
Problem
Conventional tessellation in 3D graphics systems results in uneven screen-space sampling due to uniform world-space sampling, leading to unproductive workloads and degraded image quality, especially when perspective foreshortening occurs.
Innovation Solution
A method that modifies parameters to account for perspective foreshortening by computing near and far target step sizes for each edge of a geometric object, formulating a warp function, and blending warped barycentric parameters to produce sample vertices in screen-space, ensuring more efficient computational effort and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform world-space sampling is used for tessellation, then the tessellation process is simple and consistent, but the screen-space sampling becomes uneven leading to degraded image quality and unproductive workload
Solution Approach 1:
The patent transforms uniform world-space sampling parameters into non-uniform screen-space sampling parameters by applying perspective correction calculations. The system computes adjusted step sizes and barycentric parameters that compensate for perspective foreshortening, converting the sampling distribution to achieve uniform screen-space coverage while maintaining a simple tessellation process.
2Productivity
If uniform world-space sampling is used, then computational workload is evenly distributed, but severe foreshortening produces very dense tessellation at depth and very sparse tessellation close to viewer
Solution Approach 1:
The patent applies different sampling densities to different regions of the geometric object based on their screen-space importance. By calculating perspective correction factors for each sample point, the system creates locally adapted sampling densities that ensure consistent detail quality across the entire rendered image, with denser sampling automatically applied where perspective foreshortening would otherwise cause sparsity.
3Manufacturing precision
If perspective correction is applied to achieve uniform screen-space sampling, then image quality improves, but computational complexity increases
Solution Approach 1:
The patent performs perspective correction calculations during the tessellation phase itself, rather than as a separate post-processing step. By computing the corrected barycentric parameters and step sizes upfront during mesh generation, the system achieves uniform screen-space sampling without adding complexity to the subsequent rendering pipeline.
Data Source
AI summary
One embodiment of the present invention sets forth a technique for warping uniformly generated barycentric parameters to compensate for perspective foreshortening during tessellation of a geometric object. Near and far step sizes are computed for each edge of the geometric object. A warp equation is associated with each edge. Coefficients for each warp equation are computed from near and far step size for a corresponding edge. Uniformly generated barycentric parameters for each edge comprise an input variable for each corresponding warp equation. Warp equation outputs for edges of the geometric object are blended together using a linear blend function to generate vertices comprising geometric tessellation samples from the geometric object.