Hasta La Motion!

I received all the layers for building a SSS composite on a character (tentacle from my other posts) and I was having an issue with the backscatter. First motion vector problems, now sss! In trying to better understand how skin works I came to the conclusion that my layer order should be.

Backscatter <merge(plus)> Subdermal <merge(plus)> Epidermal <merge(plus)> Specular <merge(plus)> Reflection <merge(multiply)> Ambient Occlusion.

I get a decent result with everything but the backscatter. It doesn’t seem to be doing much at all. When rendering inside of Maya the results look very good – but consequently something is happening when we render the SSS as layers for compositing. My questions are:

1) Are we approaching this the correct way with the type of layers? I believe we need a diffuse layer so I mentioned that to the 3D guy and he’s going to try to get that to me tomorrow.

2) I would think that the epidermal and subdermal need to have some sort of transparency map applied to them, but maybe I am wrong? They look awfully opaque so I was reducing their opacity inside of nuke.

3) Is there a specific way that nuke needs to handle the layers? Ie: Specific math to replicate the look from maya?

Please check out my script in the images below. The images that have backgrounds are renders from the Maya artist. You can clearly see the transparency in the suction cups of the tentacle – thats what I am losing in Nuke. You can also see a render of how the backscatter should interact with the epidermal. You can download 1 frame of each pass along with my nuke temp project here (if you want to play around):

http://nickguth.com/vfxtalk/RenderPasses.zip

If you guys have any thoughts or processes that would be greatly appreciated! We’re trying to nail out what render layers we need this weekend before we pound the render farm at school with 50+ shots. Thanks!

For those who are going to download the files to look at: Could you let me know if the passes look correct? I was thinking the fresnal pass looks kind of wrong, but I don’t really know for sure.

Cheers.