Denoising produces black pixels around specular bright areas

[daniel2SH2D]

Hello!

After rendering an animation sequence, denoising the renders with anything but the gentlest almost invisible settings using the Noice denoiser results in what look like black NaNs / black pixels around specular highlights.

I've set the log to 'debug' and there are no warnings other than that I'm calculting a lot of rays and might want to lower some sample settings!

Any idea or experience with the denoiser getting freaked out by, say, the Arnold physical sky? Or why am I getting black pixels when denoising?

Many thanks

Daniel

[thiago.ize]

I'm not sure why that could be happening. A guess is that maybe the image you're trying to denoise has infinite or near infinite values, which is more likely if this is a 16-bit float (half float) exr? You can use the oiiotool that comes with arnold to see if the values are really high. You run it from the command line using: oiiotool --stats your_image.exr
Here's what it looks like for me with a good image, which shows no nans, infs, and the largest value is 17.171875:

$ arnold/bin/oiiotool --stats Hall.exr

Hall.exr : 3584 x 1792, 3 channel, half openexr
Stats Min: 0.001424 0.000858 0.000474 (float)
Stats Max: 13.546875 16.046875 17.171875 (float)
Stats Avg: 0.283467 0.193333 0.125732 (float)
Stats StdDev: 0.400484 0.388182 0.351394 (float)
Stats NanCount: 0 0 0
Stats InfCount: 0 0 0
Stats FiniteCount: 6422528 6422528 6422528
Constant: No

[maxtarpini]

You ain't sure why that _could_ happen ? Jeez, must be a 'senior moment' 🙂

Hint : geometry against the 6EV white background is really difficult to render.. with or without a denoiser.. dark pixel blocks are denoiser artifacts, jagged edges are a filtering artifact... as you see they both happens only against the super bright background.

[maxtarpini]

Reduce the denoiser window so the denoiser won't have to filter against high freq spikes and low freq stuff.