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Old 08-20-2013, 08:33 AM   #1
Haikuka
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Claire
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Question SSS and colour bleed using the tony sculptor method

Hi there,

I'm writing a thesis on Subsurface Scattering and am doing a ton of research, one method I have found is done through connecting various fast_skin shaders through multiplyDivide nodes in maya in order to create an RGB colour bleed. It works well, however, I have encountered one problem, the degree of bleed seems to be dependent on the scale of the camera. Does anyone know why this is and possibly how I can fix it? I'm more interested in the why than a fix, however a fix would definatly be an added bonus

The forum that details how the original works is here: link to page

This is the shader network:

This is camera scale 1:

This is camera scale 11(closer to the effect I want):

Thank you for your help ^_^

Last edited by Haikuka : 08-20-2013 at 09:11 AM.
 
Old 08-22-2013, 05:00 AM   #2
pap87
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John Papafotiou
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Scaling the camera rarely goes well with shaders like sss. Best to just leave it at 1. As for the why, I have no idea, but I never touch it after coming to the same realisation as you.

Regarding your method for separating the rgb for colour bleeding in sss, I believe the new sss shader (I don't remember its name off the top of my head, I think it's misss_fast_shader_2x or something like that) does exactly that. It has 3 channels for rgb to the control the sss scattering radius. Best of all it would most likely render faster as it's all contained in 1 shader rather than 3. You may need maya 2013 though but I can't say for sure.
 
Old 08-22-2013, 08:52 AM   #3
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Quote:
Originally Posted by pap87
Scaling the camera rarely goes well with shaders like sss. Best to just leave it at 1. As for the why, I have no idea, but I never touch it after coming to the same realisation as you.

Regarding your method for separating the rgb for colour bleeding in sss, I believe the new sss shader (I don't remember its name off the top of my head, I think it's misss_fast_shader_2x or something like that) does exactly that. It has 3 channels for rgb to the control the sss scattering radius. Best of all it would most likely render faster as it's all contained in 1 shader rather than 3. You may need maya 2013 though but I can't say for sure.


I finally found out what the most likely reason is, the fast shaders all use lightmaps, which, to my understanding, calculates the depth of the subject by firing out rays. Scaling the camera makes those rays shorter, messing with the perceived scale of the model. Thatís what I've been able to deduce... it makes sense in a way, but makes me want to understand how lightmaps work more XD

Fortunately, I'm working on 2013 (yay ^_^), and I did see that shader. But its rather different that the other fast shaders, and I just canít work out how to use it. What controls what and where should everything be? I have tried to find documentation and tutorials on it, but everything I read is extraordinarily vague in the area of how to actually use it T_T If possible, could you point me in the right direction or give me some tips on how to use it? Even just a screen cap of your settings for it would be absolutely amazing!
 
Old 08-22-2013, 11:01 PM   #4
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These links should shed some light on how to use it.

Yeah it does look a lot different to the original sss shader but i think when you get the hang of it, you won't look back.

http://forums.cgsociety.org/showthread.php?t=1052423
http://forum.mentalimages.com/showt...n-sss2-by-doing
 
Old 08-22-2013, 11:01 PM   #5
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