Solving aliasing from shading with selective shader supersampling

• Aliasing from shading, especially specular highlights on sharp features, is unsolved.
• We give a detailed analysis on the origin of this type of aliasing.
• We can predict if aliasing from shading occurs in object space.
• Key is the idea to perform selective supersampling in object space.
• We will implement three algorithms able to antialias the described artifact.

Existing GPU antialiasing techniques, such as MSAA or MLAA, focus on reducing aliasing artifacts along silhouette boundaries or edges in image space. However, they neglect aliasing from shading in case of high-frequency geometric detail. This may lead to a shading aliasing artifact that resembles Bailey's Bead Phenomenon—the degradation of continuous specular highlights to a string of pearls. These types of artifacts are particularly striking for high-quality surfaces. So far, the only way of removing aliasing from shading is by globally supersampling the entire image with a large number of samples. However, globally supersampling the image is slow and significantly increases bandwidth consumption. We propose three adaptive approaches that locally supersample triangles only where necessary on the GPU. Thereby, we efficiently remove artifacts from shading while aliasing along silhouettes is reduced by efficient hardware MSAA.

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