good old flicker issue, please help!

#1

hi there,

i have this little scene with a short camera pan. as u can see theres flickering on the fume hood, the dark pillar on the left and a bit on the tabletop. here’s the movie file:

flicker example

i use FG only, no GI. i do think the problem is a material setting (or so i assume, not sure). i dont use any displacement or bump maps and use arch&design (mi) materials. i use fast (interpolate) reflection settings as when i dont theres grain all over the place. my fast glossy interprestation settings are: neighbouring points: 8 for reflective and 6 for refractive interpolation and i check “single sample from environment” for less grain as well.

my FG settings are: density 0.8, rays 250, interpolate 30. i save my FG map and read only at render. sampling quality is 4/4, changing that doesnt help me either…

im getting bit desperate as i’ve been doing LOADS of testing but cant get rid of that flicker. anybody got any ideas?
THX loads for time and help

s

ps: oh yeah, and im using MR daylight system with mrsky and mr sun plus mr sky portals for the widnows

#2

Try a FG density of 2.0, Rays 250 and interpolate to 150. If you loose fine shadow details, you can always render a separate ambient occlusion pass, and multiply it back on top of a GI pass to restore lost detail from interpolation.

#3

I think your problem is the interpolation. It is only intended for flat objects. And I would not use it in animation ever. I dont think you are having any lighting issues. Just the interpolated materials. You should check highlight and final gather only, and uncheck interpolate in your material, run a test animation, you will know for sure.

Regards,
Mike

#4

hi!

mike, u r right, it is caused by the interpolation. problem is if i turn that off the reflection gets REALLY grainy, not acceptable really, no matter how many glossy samples i use. also, theres some flickering on the table and pillar nonetheless. see here:

flicker 2

is it maybe advisable to “fake” the reflection? or any other ideas? really greatful for your help! thank you!

s

ps: how do people usually treat this problem? i seem to have flickering and or very visible grain in ANY reflective material i use…

#5

First, I noticed that the grain is not moving with the geometry. You should uncheck lock samples, and check jitter in the sample quality rollout. As for the grain, you could use a less intense env map. I sometimes use a tiff that I rendered of the mrSky. That way I am not getting samples hitting a VERY bright env map. I also think that some of the grain/noise is coming from your sky portals. What are the sample set to on them ?
When I am rendering alot of glossy surfaces I usually have to up the AA to 4/16.

Regards,
Mike

#6

thx a lot, all that helps a lot! getting good results with increasing sky portal samples to 32 and unchecking lock samples. just test rendering with 4/16 samples settings. will post result once done.

about changing the environment map settings: as im using daylight system, mr sky is used as background and when i try to use a custom bitmap it always renders out black. so i thought id make a sphere around scene, grey ambient/diffuse (for test reasons) and 100% self illumination and make it invisible to camera and uncheck cast/receive shadows. that should do the trick no? thing is, i dont really see any changes in the grainy reflection… ?

thx a lot, im learning big time here!

s

#7

hi,

here’s the new render:

example 3

flickering is gone, not entirely but good enough. the grain on the fume hood persists. what i tried is to put a different map in the environemnt slot in special purpose maps rollout, still no decrease in the grain unfortunately. would the mia_envblur shader help here maybe?

thank you, i am definitely getting somewhere here!

s

#8

ok, i think i found a way to reduce the noise. i limit the maximumi reflection distance in the advanced rendering option of the material so the far away stuff isnt reflected. this reduces the noise quite a bit. not completely but it seems almost satisfactory.

will rerender and post. s

#9

When using a custom bitmap with the daylight system, its just a matter of intensity. If it rendering black you will need to boost the output of the bitmap, mabey ALOT.

When using a dome around your scene you would not want it invisible to camera. Otherwise you will still get reflections of the mrSky.

Looking much better now. Another trick to reduce rendertimes is to set your max reflections on the material to 1, or mabey 2. Most times you cannot tell the difference.

Regards,
Mike

#10

i’ve almost got what i want but yeah, shorter rendertimes would be quite welcome :slight_smile:

“Another trick to reduce rendertimes is to set your max reflections on the material to 1, or mabey 2. Most times you cannot tell the difference.”

how do i do that? as far as i am informed i can only change it in the FG rollout (trace depth). can i also change it in the material itself? are you talking about max trace depth in advanced rendering options rollout?

thx! s

#11

In the advanced settings rollout on the A&D materal. There is a reflection limit.

Regards,
Mike

#12

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