Unsquared roughness of some shaders #50355

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opened 2017-01-02 01:28:02 +01:00 by Vilko Lafliksyon · 4 comments

After several discussions with concerned individuals and confirmation from Brecht on the Cycles mailing list, it appears that the roughness on the refractive, glass and glossy shaders are unsquared, the opposite of expected behavior for roughness on such shaders. This cannot be changed for backwards compatibility, but the manual states nothing about this and there's been much speculation and confusion about the issue, a lot of people thinking it was an issue with color management when in fact, it is not. So I suggest that it be specified in the paragraphs pertaining to the roughness of those shaders that the values are unsquared, and that for expected result, if using anything else than an image on which the values have already been squared, the input should be passed through a math node to square it.

The mailing list discussion is attached as a text file if you need more details.

cycles-roughness.txt

After several discussions with concerned individuals and confirmation from Brecht on the Cycles mailing list, it appears that the roughness on the refractive, glass and glossy shaders are unsquared, the opposite of expected behavior for roughness on such shaders. This cannot be changed for backwards compatibility, but the manual states nothing about this and there's been much speculation and confusion about the issue, a lot of people thinking it was an issue with color management when in fact, it is not. So I suggest that it be specified in the paragraphs pertaining to the roughness of those shaders that the values are unsquared, and that for expected result, if using anything else than an image on which the values have already been squared, the input should be passed through a math node to square it. The mailing list discussion is attached as a text file if you need more details. [cycles-roughness.txt](https://archive.blender.org/developer/F425894/cycles-roughness.txt)

Changed status to: 'Open'

Changed status to: 'Open'

Added subscriber: @Eranekao

Added subscriber: @Eranekao
Aaron Carlisle self-assigned this 2017-01-02 01:51:10 +01:00

This issue was referenced by 3267

This issue was referenced by 3267
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Changed status from 'Open' to: 'Resolved'

Changed status from 'Open' to: 'Resolved'
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Reference: blender/blender-manual#50355
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