View Full Version : will SSS ever get Flicker Free ???!!!

06 June 2007, 08:07 PM
hi ,
I am a blinn shader applied on the characters and i am using the built in SSS shader in the blinn .
basic scene setup :
1 area light with 64 samples
2 point lights with dmap shadows
1 direcctional light with no shadows
Fg with seconfary bounces on

the results : it flickers like hell

I have gone upto 1k samples and still it seems no use .
The miss_fast_skin shader wont flicker , but as you turn on the "use indirect illumination" option and it starts flicker as hell .
Is there a way to stop the blinn shader taking the fg into the SSS calculation .

or using SSS with FG in animation not a good choice .

06 June 2007, 09:44 PM
Attribute editor for the object, /mental ray, theres option for cast/recieve final gather. Cant tell for sure if it applies to the lightmap compution on the sss aswell. Should do thought..


06 June 2007, 06:29 PM
I am using SSS on the character's face and hands , and i want them to be effected the FG rays .
This time i went upto 2k and still no use .
Even if i take it out as a seperate pass , how can i stop the flickers . :(

06 June 2007, 09:28 AM
have you not considered compositing the two effects together? render a pass with the hands/face in a nice strong skin pose and then do a second render of a default lambert or similar material with the ambient/fg render effect then mix the two in your comping software?

just a thought

also - have you had a read of this - advanced final gather rendering:

06 June 2007, 04:26 PM
thanks for the reply ,
Yes i have tried to take out a seperate pass for the SSS , but still the SSS pass flickers by its self .

06 June 2007, 06:14 PM
which kind of Aerea light do u use? The "native" one within maya (wich need probably values you set), or the one coming with the MR tab in any light? (wich i would not recommend, to set it this high.. render will take hours, and - yaeh... you won´t have flickering at all) ..

So area lights can flicker.

FG is flickering as well. you need to go for a FG Map stored an disk. Set FG Map to "freez" after you took the map.
getting the map: set rebuild to "off" and render FG´points from the most important camera angles. then ste it to "freeze". This works only good, when no objects are moving. Those has to be composited.

Maya 8.5 works different.

06 June 2007, 07:16 PM
thanks for the reply Caypiranha

I am using mentalray's area light settings ( using the "use light shape" check box on and a 100 samples now )

I cannot use FG map or the freeze option as the character is involved in animation . Now i have seperated the character face pass but it still flickers . Applied usebackground shader to all other parts

1 mr area light with 100 samples (quadratic falloff )
IBL node to almost pure white .
0-2 samples
200 fg rays
min 10 max 100 radius
20 point interpolation

06 June 2007, 12:00 AM
Can u tell us more about the SSS setup please? Lightmap samples etc. If you said can SSS be flicker free is that mean the other objects in the scene was rendered fine???

06 June 2007, 03:09 PM
yes , everything else is rendering fine .

i have gone upto 2048 samples .

Another thing i found out that SSS is rendering fine with only lights enable , but as long as "use indirect illumination" option is turned off .
The flickering is being caused by the FG .
I removed my HDRI setup to a single colored IBL but still in didnt help . Will i have to go up to 3000 rays or something

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06 June 2007, 03:09 PM
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