Jumping and jittering in animation

[ksgfx]

I continue to have jumping/jittery shadows in my animations. If you look at this animation (1.4mb) you'll notice the jumping especially around where the teeth meet the bone. As a side note you'll also notice a few bad frames (flashes) any idea what causes these?
http://demo.dentistryonline.com/nmdgraphics/skull.wmv

All of my materials are vray materials. I'm rendering with IR+QMC and Adaptive Subd on the AA. Here are my settings, everything else is default.



I also want to note that I have turned the IR up to High animation quality and still got the jumping shadows. As always any help is greatly appreciated. Thanks.

[jacksc02]

was it rendered from a saved irradiance map?

[ksgfx]

Yes I'm using VArcht's plugin so I can save off the irmap and then load them back in, avoiding the double time hit when rendering fields. Although now I'm going to go run a test and see if it makes a difference.

[natty]

you may find that your Interp samples are way to blurry .. put them back down to 20, also change your sample look up method.

[ksgfx]

Thanks Natty.
Any suggestion on best sample lookup for animation?

[natty]

try the Interp samples firsts ... then take it from there.

[sv]

could you lower the setting of the adaptive amount to about 0.5 or 0.6 or something. Would this have any noticable affect on the jittering?

[Morbid Angel]

quasi monte carlo my friends.
samples 25
end of story.

[paulison]

just to clarify...

under QMC sampler change Min Samples to 25?

this reduces grain and flickering when using QMC for secondard right?

[Morbid Angel]

no, I ment quasi monte carlo for primary and secondary gi bounces.
QMC sampler if using qmc aa is noise: 0.003, global subdiv multiplier 4.
aa filter mitchel natravali

but with quasi as gi I tend to use adaptive subdivision with 0/2, 0/3 as it smoothes the gi samples better.

[flipside]

QMC for first and second bounces takes ages to render.

I would adjust your ir map settings:
min/max=-3/-1
hsph=70
interp samples=20
blur GI=0
clr th=0.4

the lower hsph and higher clr th will make up for the increased time of using better min/max rate, so calculation time will be approx the same as your times now.

How are you lighting that skull? By using vraylights without the store with ir map option you can get pretty good results, without any need for GI (or the dome light could be good too)

[ksgfx]

I have tried the primary and secondary QMC route and wasn't impressed by the render times, plus I feel like I would have to start all over tweaking new settings.

Thanks flipside, I will run a test with those settings and see what I get. For lighting I'm using both v-ray hdri and two v-ray lights for a spot and backlight effect. If I turn off the hdri I don't seem to get quite as dynamic of lighting. I'm not familiar with the "store w/ ir map" control, but I checked and I don't have them on.

[flipside]

Ok it's a good thing in this case that you don't use the store with ir map option.

Hdri for lighting is always tricky, because you need higher ir map settings to make it splotch free. Now I see why you used 100 subdivs.

What you could do is scale down the hdri map a lot with hdr shop ar any other program capable of editing hdr maps. Scale it down to about 200px width and then apply a bit of gaussian blur too. This will speed up ir map calculation a lot, and you can get away with lower ir map settings. This makes the hdri lighting less detailed of course, but in your scene you won't notice it. By resizing and blurring the map, you get rid of the 'extreme' pixels in it (pixels with very bright values right next to pixels with very low brightness for example), which makes it easier for the ir map to create a noise free result.

here's an example (images with exact same ir map settings, only hdri map changed)

original map:


resized to 200px and gaussian blur of 4:



detail of the original hdri:


resized map: