Animation Shimmer - Most likely cause?

[Morne]

Hi guys

I have an animation that is shimmering heavily, but most noticebly on grass, trees etc (any forestpack obect)


Now I do realise my settings are pretty low, but we just want to see what single setting can have the biggest impact on getting better results, yet still keep the lower render times (yeah I know, countering my own statement!)

So for AA I have 2,24
Noise 0.1 (in an ideal world we'd set this to 0.05 or 0.03)
Denoiser, default, denoising per frame at render time (since we're outputting to tga for this one!)

So suggestions.....
Raise min to 3 or 4
or Lower Noise
or ditch Denoiser?

EDIT (Extra info):
Scene is lit with VRaySun and VRaySky shadow bias 0.2
I've also increased the Secondary rays bias to 0.001, just in case there's any coplaner faces (which there shouldn't be, but you never know)

[Morne]

I wonder if simply switching to Quadratic AA will help, instead of default Lancozfilter.....

[^Lele^]

You're on the right track.
Perhaps raise min AA to "pad" the render for the fine details.
Ultimately, look at the SampleRate RE to figure out if you are hitting the noise threshold (oftentimes, with high ones, the max aa will not come into play, by a margin.), or if the sampler stops mostly around the low AA subdivs.

[Buck]

I wonder if simply switching to Quadratic AA will help, instead of default Lancozfilter.....

I think some variations of lanczos filters have a bit of sharpening to the filter, so that could be the problem. I don't know specifically about V-Ray's implementation of lanczos.

[^Lele^]

I think some variations of lanczos filters have a bit of sharpening to the filter, so that could be the problem. I don't know specifically about V-Ray's implementation of lanczos.

The one implemented in V-Ray lacks the negative component, so it doesn't sharpen.
It's very quick, and fairly sharp, so definitely won't blur.
Let's say it's as close as a per-pixel filtering, without the drawbacks.

Filters won't be of any help with thin geo, the issue with that is finding it first (particularly when a pixel is crowded with minute detail) and then to AA the data.
Shimmering in Morne's case looks like under sampling: the geo is found only some of the time, across an animated sequence, and hardly ever properly anti-aliased (as the noise threshold is very high.).

I stand to be corrected, ofc.

[Buck]

can you post a video of the issue? Even if it's just a crop of the grass, if you can't show the rest.