[Soc-2016-dev] Weekly Report #04, Cycles Denoising

[Sergey Sharybin]

Didn't read in all details, but seems a very nice progress :)

Would it be too much/crazy to ask showing some render/denoise results? ;)

On Sun, Jun 19, 2016 at 6:22 PM, Lukas Stockner <lukas.stockner at freenet.de>
wrote:

> Hi!
>
> This week, I finished the basic denoising code. It took a bit longer than
> expected, there were a bunch of annoying issues in the numerical code like
> swapped indices etc. I'm pretty sure there's still a bug somewhere in there
> since some corners get completely over-blurred, but that shouldn't be so
> hard to find.
> For many scenes, though, it already works pretty fine - here's an example
> of the Classroom benchmark scene, rendered at 300spp and denoised:
> http://www.pasteall.org/pic/104326 (Annoyingly, though, I forgot to save
> the noisy version as well and didn't want to delay the already pretty late
> report by 2h to render it again, so there's no direct comparison).
> The biggest problem in that scene (and many others) are the shadow edges
> that are completely gone, so I tried a little trick inspired by the paper I
> linked in report #2 - instead of just using x and y as screen position
> features, using x, y, x^2, y^2 and x*y (essentially, the second-order
> taylor expansion in screen space) produces much better shadows, as you can
> see here: http://www.pasteall.org/pic/104327
> However, you may also notice that the out-of-focus desk in the lower right
> corner has a lot of artifacts now - that's why an adaptive picking of the
> taylor order, as described in the paper, is needed to use the higher order
> fits properly. Therefore, I've just left the second-order fitting as a
> (disabled) option in kernel_types.h for now.
>
> Also, I did some non-denoising related Cycles stuff again:
> - Updated the multiscattering microfacet patch
> - Created a patch that allows to use custom properties of Objects in the
> Attribute node in Cycles for per-object shader customization (D2057)
> - Bisected and fixed a bug in the recent nodes refactor (T48657)
>
> So, next week I'll first clean up some smaller issues:
> - GPU denoising isn't implemented yet (the kernel code is the same, but
> the wrapper code has to be added).
> - As mentioned above, a bug is overblurring some edges.
> - The new SVD code doesn't work yet.
> - It might be possible to skip the SVD altogether and use a
> eigendecomposition instead, since the matrix is Gramian and therefore
> symmetric, which means that the eigendecomposition exists and is equal to
> the SVD (up to the signs of the columns, which don't really matter here
> anyways).
> - Border rendering is broken.
> - Some scenes (like the Classroom) don't show the feature passes.
> - The filter strength option doesn't do anything yet.
>
> Next to that, I'll try to improve results for some corner cases like
> shadow edges and strong reflections on glass.
>
> So, that's my 4th report. You can already try out the denoiser, but it's
> not working 100% correct yet. So, in case it's already working well for a
> scene - great! And if it isn't, it hopefully will do so next week ;)
>
> Lukas
>
>
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>
>


-- 
With best regards, Sergey Sharybin
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