Reflection Flickering

[grievecr225]

I'm having some trouble with flickering in glossy reflections.This is 3 frames of an animation where the camera is panning across. I have theses wine bottles that have reflection and refraction in the glass material. Nothing I do eliminates it.I have the max samples jacked up to 60 and the min shade rate at 196. It improves is but does not eliminate it. I have ruled out the GI. I'm stumped. Has anyone run into this and successfully fixed it?
Thanks in advance.

[^Lele^]

Too wide a target to hit.
Can you share (offending parts of) a scene, so we can look at it?

[grievecr225]

Unfortunately I can't share the scene. The problem is mostly with the bottles of wine. It's not a material issue or geometry issue either. I've confirmed that. It's a noise issue. Locking the noise pattern Improves the solution. But still doesn't completely fix it.

[Joelaff]

When you say you ruled out GI, how so? You completely turned off GI and you still have the issue?

First thought would of course be using light cache GI for glossy rays. You can test this a few ways, but switching to brute force+brute force is the simplest test. Render a few frames and see if it goes away.

With light cache make sure you are using the animation preset. (Vray5). Try increasing the retrace threshold. Please post if any of these work.

Other general things would be increased MIN samples to 2-8. Try using the Soften image filter with a radius of 1.98 up to as soft as you want (generally under 4). This makes beautiful highlights on fine details and a much more true camera look. It is of course Softer and some people don’t like that.

[grievecr225]

GI is completely turned off. What sample are you referring to? Progressive Image Sampler? I have that set to 1-60 and it's still doing it.I'll try the filter see if that helps.

[Joelaff]

GI is completely turned off. What sample are you referring to? Progressive Image Sampler? I have that set to 1-60 and it's still doing it.I'll try the filter see if that helps.

LOL. Well, that rules out GI alright!

Yes, Min subdivs. for the progressive sampler. (or the bucket sampler). That can make a big difference with small highlights. It makes a much bigger difference than the Image Filter will.

[M.Max]

Changing from default "adaptive light" to "light tree" under Global Switches might be a way to fix this.
At least It did for this video.
https://vimeo.com/341757656
The link for the version that have flickring is in the description.

[grievecr225]

Already have it on light tree

[fixeighted]

Just a thought - could it be some coplanar faces stuff going on?
EDIT: I see you have already checked the geometry, so maybe not.
EDIT: I see what you mean I think - those tiny highlights on the bottles that look like they are fireflies? Maybe a lightsource that is bigger/softer would help?

[grievecr225]

So taking the noise threshold down to 0 eliminates it. but render times are through the roof. There has to be a way to eliminate it and have reasonable render times.

[^Lele^]

What's the setting for the glass in front of the bottles? Does it cast shadows?
Also, am i seeing ringing around highlights? Are you using a sharpening filter?

[grievecr225]

it casts shadows and I'm using the VRayLancosFilter.

[^Lele^]

Right.
It may help turning off shadow casting (from the standard max geo properties, to be sure.).
Speculars behind glass are technically made up of caustic rays, so they are inherently harder to calculate.
Make them small, use few *min* AA rays, and you may end up missing them.

My suggestion for render settings is to go back to defaults (very important!), and then just raise minimum aa to something like 3 or 4 (i.e. 9 or 16 *camera* rays are cast per pixel, regardless of adaptivity.).
MSR will need to stay low as the defaults because you will need many camera rays, more than secondary ones, in this case, to "find" the specular.
Setting it to a high value will force V-Ray to take a load of time evaluating it per each camera pixel, while still -as you saw- unable to find it each time.
After the first camera ray, and so many secondaries, the adaptive algo will think it's found what it should, and start adapting to it.
But if the single camera ray didn't find the highlight, you're not going to find it easily thereafter.

TL;DR: Try setting it to no shadow casting. Reset to defaults, set min aa to 3 or 4, see if that helps.

[^Lele^]

Also, leave GI on, the LC will help with rendertimes and finding highlights.
Set it to animation preset, and render away.

[grievecr225]

I think I got it. ended up with MSR: 6, PIS: Min 10 max 30. I'll report back if it doesn't work. Thanks for all the help!