NAN pixels with extreme values creating bright lens flares

[Alex_M]

I've got a scene which has an extremely bright pixel that I'm not sure where it comes from. It creates an extremely bright lens flare when I turn on the lens effects. When I put my cursor on it, it says "nan" instead of reading a float value. What is this and how do I get rid of it?

[milva.perkovich]

Hi,

Could you send the scene to milva.perkovich@chaosgroup.com so we can take a look?

Best regards,
Milva

[Alex_M]

Hi, Milva. I've just sent you an email containing download link for the scene.

[^Lele^]

"NaN" means "Not a Number".
I.e. the value in that pixel is out of bounds of the precision on offer, or due to incompatibilities or bugs (say, odd normal map...), it's literally not representable as a color.

There are cheap ways in post to deal with this, but it's generally much better to find the source of the issue in the scene to be rendered.

[Alex_M]

I think I found the culprit! The glass material on the sliding door had Fog Bias amount of -10. I set it to 0 and the bright pixel was gone.

[^Lele^]

aaaah, great find!
Please do send the offending bits to support!
EDIT nevermind me. never saw your previous post.

[milva.perkovich]

Hi Alex,

Thank you for the scene and the information, they were very useful for the problem identification.
This bug is now logged in our internal bug-tracking system (VMAX-10305).
In addition: enabling "Calculate Denoiser" option resolves the problem with the overbright Lens Effects. You can use this as a workaround in case you want to keep the Fog bias values unchanged.

Best regards,
Milva

[Alex_M]

Thanks, Milva.