Black pixel artifacts in Karma (Random Walk SSS)
13202 33 3- Werner Ziemerink
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- jsmack
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Either switch to uniform sampling, or set variance to 0 (for interactive renders). Variance sampling is still broken, or at least is completely unacceptable in image quality.
I somewhat disagree with the notion that pixel samples can be non-uniform, it always leads to artifacts. VRay with adaptive dmc always has weird holes in the dark areas because the adaptive sampling didn't use enough samples. Karma is even worse, where the holes are always pure black pixels on any shaded areas.
I somewhat disagree with the notion that pixel samples can be non-uniform, it always leads to artifacts. VRay with adaptive dmc always has weird holes in the dark areas because the adaptive sampling didn't use enough samples. Karma is even worse, where the holes are always pure black pixels on any shaded areas.
- Werner Ziemerink
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- Werner Ziemerink
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- blackpixel
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- jason_iversen
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Looks good - is that using the new random-walk SSS?
And yes, we're looking forward (anxious) for a fix to the variance issue too.
And yes, we're looking forward (anxious) for a fix to the variance issue too.
Jason Iversen, Technology Supervisor & FX Pipeline/R+D Lead @ Weta FX
also, http://www.odforce.net [www.odforce.net]
also, http://www.odforce.net [www.odforce.net]
- Werner Ziemerink
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- Siavash Tehrani
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- Werner Ziemerink
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- Werner Ziemerink
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- Werner Ziemerink
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- jsmack
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With uniform sampling, I think everything takes about the same amount of time. Did you notice that the albedo of the random walk sss seemed low? It also seemed like the mfp was much lower in appearance than with the old diffusion based sss. The resulting color seemed pretty far removed from the color parameter, as well as the sss color seeming to have a very different effect than with the other models. Is this just the nature of the algorithm?
- dlee
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dlee
Do you have scale applied to the object? Currently there seems to be a bug with random walk where it can behave erratically with scaling which might account for larger differences (this will be addressed shortly).
I do, in fact. The shell was modeled in mm or something so I scaled it down by 0.01.
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- Werner Ziemerink
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Anyone seeing crashes with husk renders containing the random walk? When I render with 256 samples, they go for several minutes and then it exits as if it's done, but no image is output. I assume it crashed because the time elapsed is too low for it to have reached 256 samples. It doesn't seem to have trouble with 16 samples, or interactively. If I render at a low enough resolution it will output, but anything such as 960x540 or above does not.
https://www.dropbox.com/s/y1xfqdef5i1pt8g/random_sss.zip?dl=0 [www.dropbox.com]
https://www.dropbox.com/s/y1xfqdef5i1pt8g/random_sss.zip?dl=0 [www.dropbox.com]
- Werner Ziemerink
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