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View Full Version : SSS & GI always flickers ?



crisblyth
11-29-2010, 01:43 PM
Hey all,

So, I've got this very cliche marble chess pieces & chessboard and I'm using SSS & GI (attempted FG and MC) and I always, always, no matter if a cache or put all the setting all the way up to 11, Still get flickering.

It seems that even if I just have SSS it flickers, even if I put it up to 1000% quality..

But I MUST be doing something wrong.

Does anyone have any info or knowledge on this ? cos this shouldn't be too hard. I've spent more time with the settings than on the work..

cheers,

crisb.

3DGFXStudios
11-29-2010, 02:23 PM
It doesn't have to flicker. Do you have radiosity turned on and if so what are the settings? How many samples are you using? What's the AA setting? Can you cache the GI? What SSS node are you using? What kind of material are you trying to create?

crisblyth
11-29-2010, 04:51 PM
Hey, thanks for the reply, here's my answers :)

-So, I've set my samples from anywhere from 500 to 1500, still flickers
-I've tried MC and FG
-I've put the AA setting to around 15
-I've tried cacheing the GI, but I feel that the SSS is the culprit
-I'm using the newest SSS node that ships with 9.6
- I'm trying to create a marble chess pieces that are backlit.

Any info (or marble shaders that don't flicker) would be appreciated,

thanks !
crisb.

ArtGoblin
11-29-2010, 05:35 PM
I've had similar problems when using SSS shaders in the past, is there any way for you to like apply the shader/surface settings to a sphere or something simple, and post that scene with all the same light setup ect. so people can take a look under your scene's hood and disect it? (by the way sounds like your AA settings are unnesisary high, and I don't think it's the likely cultprit)

bazsa73
11-30-2010, 01:25 AM
It flickers. SSS1 and SSS2 flicker because those are preprocess shaders.
The one which does not flicker is the omega shader from the legacy.
Use it with MC without interpolation.
But then again, you never know when it flickers or not and today's apps became
so unpredictable and overly elaborated that in the jungle of uncertaintity you just
never can be sure. Because there's always something which drives you crazy and
you end up wanting to do something very simple without computers.

3DGFXStudios
11-30-2010, 02:20 AM
If you are using the Sigma2 node you should leave the gamma 1.0. Any higher values will make it only worse. Quality should be good if you set it to 100. Transparency can also be 0. You don't need it to get a nice SSS effect. The most important value is the "Distance".
Make sure this value is high enough. You can set this value even higher than the size of your object

3DGFXStudios
11-30-2010, 02:28 AM
Here is a preview I did with the settings I described.

Shiny_Mike
11-30-2010, 04:16 AM
You might try using the Sigma2 and Final Gather, just set the GI to cache and uncheck Interpolated. Worked great for me a few days ago, no more flicker.

3DGFXStudios
11-30-2010, 04:17 AM
yes for sure uncheck Interpolated....

bazsa73
11-30-2010, 06:45 AM
Check this out,
SSS1 shader + photoreal motionblur + MonteCarlo full evaluation
For me it seems ok but "may beee" you want even less flicker

3DGFXStudios
11-30-2010, 06:51 AM
I would use a lot more radiosity rays. between 1500 and 3000 is a good value. and turn of motion blur if you don't need it

skywalker113
11-30-2010, 09:58 AM
Dome lights dont make any radiosity splotches. I often light a studio shot like this...

bazsa73
11-30-2010, 10:52 AM
I would use a lot more radiosity rays. between 1500 and 3000 is a good value. and turn of motion blur if you don't need it

yes right, I cranked it up but kept mblur

3DGFXStudios
11-30-2010, 11:55 AM
Dome lights dont make any radiosity splotches. I often light a studio shot like this...

with so many dome lights it's not going to render fast. you can use just one and end up with almost the same result. Dome lights are DOMES so the light will come from any direction except the floor. It's a bit like ambient occlusion. So you setup doesn't make any sense to me :)

imshadi
07-18-2013, 12:58 PM
I was wondering what was going wrong with sss / sss2 in a scene with Montecarlo GI that suddenly began to flicker. Turns out the flicker tends to disappear the higher the resolution of your render. If lightwave's SSS is anything like Mental Ray's. Lightwave creates a 3D Matrix in screen space where it stores light values and it does the blurring/blending that looks so cool. In MR you can find a special place where you could set the size of this matrix, and indeed the size determined the stability of the shading. LW seems to set this value without user intervention as proportional to the pixel size of you image. So, a higher resolution brings out a better result.

On LW 9.6 I used to set all the samples really low so that all my sampling depended on the number of motion blur passes that I chose and this used to take care of the SSS flicker, but right now it seems the matrix gets calculated only once. So more MB passes do nothing. Newtek's solution makes for faster rendering, but poorer quality and the lack of control / documentation just makes it harder to solve problems. I hope they resolve this situation in future manuals. For now I hope this contribution helps someone.

PS: Skin, Omega and other shaders do not look as cool for the Pixar kind of SSS that people usually look for. I used to like chanlum as a quick fake alternative but they haven't updated it to work with LW after 9.6.

Cheers!