CGTalk - cant get misss fast skin to work

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gohoppang

01-16-2008, 07:36 AM

I have been struggling with it for hours now. After endless googling and watching the gnomon tutorial on it over and over again, I am still in no where near finding out where I went wrong.
I thought I might have made a mistake hooking up all the nodes properly so I downloaded a script that automatically does it for me.
yet it still refuses to work!

It is working sort of like a blinn at the moment with no sss.
If anyone could point me in a direction as to where I might have gone wrong it would be much appreciated.

I have three lights pointing to the model at the moment. One keylight with decay and raytraceshadows, one front fill and one backlight. The last two does not have any decay or shadow casting turned on.

I am in a real jam. I think it might be something simple that i have overlooked.
Please help!
Thanks.

Bitter

01-16-2008, 07:59 AM

Would probably have to see the scene file to be sure. Lightmap connected? Scale correct? Subsurface areas have some weights? Looking at it where light would scatter?

Try turning weights for everything off except maybe the backscatter. . .and render. See if thin areas are red, if not, pump up the scatter weight and radius and see if it shows. If not, then something else might be wrong.

KamiNoNamida

01-16-2008, 02:09 PM

Yep, should really check out your scatter and scale values.
Maybe you could fine tune your shader via a simple object and light setup so that you know for sure where there sould be sss (maybe a simple box/sphere/etc with a very dim keylight and a good backlight ?)
Also if you could post some screens of your scene (with active grid in order to have an idea of the scale), shading network and sss parameters (that is, fast_skin + lightmap + mr texture, via the copy tab button you can get all 3 on 1 screen). Or eventually your scene file.
But as bitter said, pushing down the weights for epidermal and subdermal colors and pushing up tha back color weight and backscatter radius, with a hard light just behind, ou should at least see somehing.

gohoppang

01-16-2008, 09:06 PM

KamiNoNamida

01-17-2008, 01:51 AM

Thanks everyone for all your thoughts.
I've actually asked a friend to take a look and found out that the inverted normals were causing the problem.
He told me misss wont work unless all the normals are facing the right way.
I kicked myself for a while. lol
Good to know (though in the end it seems quite logical :s)
Although, you know, your normals probably have no reason to be facing the wrong way, ever :twisted:

:beer:

gohoppang

01-17-2008, 04:23 AM

Heya,
I modelled half of mycharacter, duplicated it, scaled it -1 in y and combined it.
Then I conformed my normals. I think it might have been in this step where I screwed it up.
I should have checked afterwards.
Anyways, I've definately leant my lesson.
Happy rendering! :)

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