V-ray Next 4.30.02 - Extreme "dancing" white pixels on any material at a distance with glossy reflections

[Vizioen]

Thanks for the research and reply Lele, fingers crossed for a working solution in the future.

[kosso_olli]

You are conflating different issues.

a) Teapots file: hide the sun disc.
Do so, the flickering is gone.

I am sorry, but I can not reproduce your results. Please open the attached file and play both frames in Chaos Player. There is still flickering going on, sorry.
Yes, it reduced by a considerable amount, but it is far from gone. There are still flickering highlights in every row of teapots!

https://transfer.px2.de/_4AQ1RQNRgdI4YR

[^Lele^]

Thanks for the research and reply Lele, fingers crossed for a working solution in the future.

I've tried both Corona and Arnold, and they both behave exactly the same.

Corona:

Arnold:

The only way to have the issue disappear, currently, is to fix the noise pattern and render to below noise visibility (this is the same 3 frame gif as the rest.):

[kosso_olli]

EDIT: Nevermind, the post is right there before Lele's last reply

[kosso_olli]

^Lele^ Did you have a chance to look at the two EXR's I uploaded in a previous post?

[^Lele^]

Yes, have you read my post above? That's the fix, as of now.
Any -potential- further build would only suppress samples of this kind, not sample them better.

[Joelaff]

I figured you just toss or clamp samples outside some threshold of standard deviation.

I am sure there are more intelligent approaches, like adding new samples in the cases outside the threshold, or blending in the smoothed light cache solution for such pixels, though maybe such methods are simply too slow.

I hadn’t seen this newer technique. Fascinating problem, really…

https://diglib.eg.org/bitstream/hand...96/121-132.pdf

[kosso_olli]

Yes, have you read my post above? That's the fix, as of now.
Any -potential- further build would only suppress samples of this kind, not sample them better.

Sorry, which post do you mean?
The two EXR's in that file already had the sun disc hidden. It works for some of the teapots, but not all of them.
Locking the noise pattern and setting a low noise threshold did not help either.

[^Lele^]

Sorry, which post do you mean?
The two EXR's in that file already had the sun disc hidden. It works for some of the teapots, but not all of them.
Locking the noise pattern and setting a low noise threshold did not help either.

I can't fathom what you did: it works perfectly fine for me (3 frame gif below + max 2024 scene.).

[kosso_olli]

I can't fathom what you did: it works perfectly fine for me (3 frame gif below + max 2024 scene.).

Lele, it seems there is some misunderstanding.

In the teapot file from post #59 the camera is moving.
In your file you uploaded in your last post, it is not. We know how to render consecutive frames with static camera without getting randomly placed highlights by now. The solution was proposed by Joelaff in post '33 by deactivating locked noise pattern:

I wonder if Lock Noise Pattern would at least keep them consistent.

His solution was confirmed by me in post #34, with an exception:

Just had to check this, because I did not think of it: Indeed it does!

EDIT: It does only work if the camera is static. As soon as it moved, you get randomly placed hightlights again.

So, I opened the scene you uploaded today, animated the camera ever so slightly, and voila: Dancing highlights (i just set metalness back to 0, sun disc is disabled of couse):




If you could take a close look at that scene again to find a working solution, that would be great. For over a month now, I am not able to produce a sequence that is looking clean. I'm seriously running out of ideas. File is attached. Thank you so much!

teapots_olli_01.zip

[^Lele^]

They are not randomly placed at all, they are well time-correlated.
The angle gets just too shallow from one frame to the next, the sun is partially hit, the highlight drowned by the samples that missed it.

This is the same issue as the OP, for which the only possible fix is to kill those paths.
The issue however is unsolved as of yet (and while it's actively researched, there is no ETA yet.), so zero the sun's contribution to speculars, and you'll be fine (your highlights will come from the sky, and the sun's halo.).

[Joelaff]

so zero the sun's contribution to speculars, and you'll be fine (your highlights will come from the sky, and the sun's halo.).

Not sure that is sufficient in a lot of cases. However, you can augment the highlights as I stated before, with an additional VRayLight disc setup to mimic the sun's position (and without setting the Directionality too high), making this light as large as you can without sacrificing the look (bigger will flicker less and render faster).

[^Lele^]

Not sure that is sufficient in a lot of cases.

I haven't found one where it doesn't remove the glints.

However, you can augment the highlights as I stated before, with an additional VRayLight disc setup to mimic the sun's position (and without setting the Directionality too high), making this light as large as you can without sacrificing the look (bigger will flicker less and render faster).

Indeed, studio work is generally a better option than using the sun directly, just like it often is IRL.
Your approach is also a wee bit better than simply making the sun disk bigger, as that would impact shadows and sky as well.

[Joelaff]

I haven't found one where it doesn't remove the glints.

Oh, sorry by "sufficient" I meant capable of maintaining the desired "look" of being in the sunlight, while simultaneously ameliorating the flickering.

Indeed, studio work is generally a better option than using the sun directly, just like it often is IRL.
Your approach is also a wee bit better than simply making the sun disk bigger, as that would impact shadows and sky as well.

Also, making the VRaySun bigger (I am assuming this is what you meant) still keeps full directionality/parallel rays. These are more accurate, but matter very little in the speculars, and lead to more flickering (hence my suggestion NOT to set a high directionality.

Of course as kosso_olli keeps saying, we shouldn't have to do any of this. It should "just work."

[^Lele^]

Oh, sorry by "sufficient" I meant capable of maintaining the desired "look" of being in the sunlight, while simultaneously ameliorating the flickering.

Eh, yes, ofc the sund disk's glints will be gone.
We could also call them tiny speculars, and then we wouldn't be fidgeting with nomenclature, ahah

Also, making the VRaySun bigger (I am assuming this is what you meant) still keeps full directionality/parallel rays. These are more accurate, but matter very little in the speculars, and lead to more flickering (hence my suggestion NOT to set a high directionality.

Making the v-ray sun bigger makes the shadows softer, and ofc the reflection of the disk is bigger too.
However, the kind of sizes one would need to make the sun disk easy to sample would also make the render awfully slow (besides being utterly unrealistic.).
This is why the procedural sky allows for a custom sun node: plausible values aren't always friendly.

Of course as kosso_olli keeps saying, we shouldn't have to do any of this. It should "just work."

As mentioned, the current "state of the art" is suppression (f.e. Corona): so your highlights are going to be gone, which is highly problematic a behaviour in itself.
If you know something the V-Ray, Arnold, Corona and Renderman Devs don't about sampling a sun disk more reliably, please get in touch: there's serious money to be made.

Here's how big a sun disk is (while being in the several millions float for intensity).