small geometry detail flickering

[glyph]

hi - any tips on how to stop very small detail disappearing from one frame to the next?

I have some fence posts viewed from a high angle and the tops of the posts come and go

My AA is -1, 4
multipass, rand, threshold 0.05

if I go to AA 5 it still flickers and of course the render time goes up

Its a very big architectural site so has quite a lot of tiny detail and everything else is great...

ta MarkC

[natty]

Try Adaptive QMC AA ...

[ShaunDon]

Hey man.

I've had problems with this too -- even when I get the aliasing fine so edges look great and there's no visible flickering, things like down light rims (small profiles) will blink on and off.

My solution has been to increase our frame render size by 1/3. That really helped in our last render -- also allowed us to kill a lot of noise from exterior grass. Our compositor likes it also since it gives him more room to fudge things, and we sample the frames back down after he's done his work.

And while you effectively double your pixel count, it's a marginal increase in render time -- our exterior (granted one large building, a parking lot, and a huge grassy field and rolling hills -- not a lot of construction) was still only 3-5 minutes per frame. As much as 7 in closeup shots.

Good luck, man.

Shaun

[glyph]

Natty - thanks - not sure which setting to change but I tried QMC - 'adaptation by effect on final result'
and changed it from 1 to 0.5 but no difference

I don't think I should be changing the early termination settings, should I?
they are: amount 0.85, noise thresh 0.005 and min samples 16


btw I'm using vr 1.09

- Shaun your idea sounds woth trying- of course I'm the compositor, renderer, editor etc so I only have one person to satisfy!
; )

[dapeter]

I think what Natty's suggesting is to use an image sampler other than Adaptive SubD AA, and switching that to the Adaptive QMC AA (or, for that matter, fixed rate).

The problem is the iterative nature of the adaptive subdivision AA - because it is not necessarily sampling the same location the same way between frames, the antialiasing itself creates artifacts in the final image. You have to use either the fixed rate or the adaptive QMC, although you may have to up the levels to somewhere around Min=1 Max=10 (for the QMC image sampler - but this also depends on the settings in the QMC rollout). Or you could try the fixed rate image sampler.

There's a good discussion (with images) of both the QMC rollout settings and the image sampler options in the help file:

http://www.spot3d.com/vray/help/VRayHelp150beta/

[samuel_bubat]

hi there !

if you have very little details that flicker... and you allready have
high antialiasing settings it could be a gi problem. !!
For example:
If your gi settings are min/max -2/-1 and you have a camera moving away from an object with very little details sometimes the details will go below
-1 and no gi will be calculated wich can result in some sort of flickering.
I had this problem with an greeble scene where an object was rotating
in front of a camera. I even had to oversample the gi to -2/1 before the
flickering disapeared.

Maybe that helps !

[gilicom]

hi i had the same problem whan i usec -1/2 , after changing it to 0,2 didn't have it again...

[ShaunDon]

This is why I say render at a larger size. You're going to have to up your aliasing or GI settings to correct the problem if you render at your final resolution. I think you'll find that you can keep the same aliasing and GI settings you have if you simply increase the frame size, and the increase in render time will probably still be less than a higher aliasing or GI solution would need.

And regardless, anything rendered larger and sampled down looks better than a render straight out of the frame buffer.

We produce our animations at 720x360 (a 2:1 aspect ratio -- we like the feel of it and it makes for easy calculations), so the last animation I did was rendered at 1024x512. The only real drawback to doing that is that your frames are going to be a lot larger in terms of file size...

Shaun

[alkonst]

you will never be able to avoid little flickering using Vray Displacement for the grass. Even if you use FIXED RATE = 5 you will get this flickering. I do not know about Adaptive QMC

[samuel_bubat]

you will never be able to avoid little flickering using Vray Displacement for the grass. Even if you use FIXED RATE = 5 you will get this flickering. I do not know about Adaptive QMC

did you allready try the gi tips from above ?