Monday, October 17, 2011

Work on the skin


For the second project we had to paint and texture the eye for my try I used a Blinn Shader and two piece of geometry, one for the eye ball and iris the other for the cornea. But the result was not satisfying the eye was looking milky and life less. At this point I let eye on the side the time to focus on the skin and try to come with another solution.

The first step before creating the skin Shader was to get a satisfying bump and displacement on the surface. I experiment few problems during the process especially with the folds in the ear and some horrible seems on the top of the head and the ears edge. To solve them I had to tweak my UV layout and find a way to export   the properly the map out of Zbrush. I used the morph target option in Zbrush to make sure I created a  displacement map and normal map that could match the displacement approximation in Maya. I prefer the normal map at end over a bump map because they don’t cast shadow but have effect on the specularity,  the displacement will take care of the shadow of the skin pores.    


































 It was time to work on the skin material. My first step was to link the bump and displacement to the skin the Mental Ray SSS fast Skin. Then, I turned everything  (diffuse, specularity, epidermal, subdermal) but back surface scattering off. When I was happy with the result I started to work on the subdermal layer, at this point my goal was to have something looking like red slime. The next step was the epidermal; I was looking for saturated skin look. The final step on the overall look of the skin material was to play with the diffuse intensity to get something looking as natural as possible. Using this method  helped me to understand what was going on and how the SSS fast Skin material behave.

It was now time to create the map for my skin shader. I started to paint her skin on Zbrush. I created the epidermal map first because I will use it as a base for the other map. This skin layer had to be paint looking slightly saturated to make sure I get the wanted final result. When I was done I export the map to Photoshop.  In this program I created the base for diffuse map by unsaturated the colors before to exported the new map back to Zbrush project it back on the mesh and tweak it. The same workflow was used to create the subdermal map but instead of unsaturated the epidermal map I saturated it and blurred it. Back in Zbrush I gave the map a more fleshy look by painting veins and noise.  I also paint a Back Scater Color map to have a better control of the effect of the light on the skin.

 




Back in Maya I was not happy with the look of the specularity. I found in a tutorial that it was possible to plug Shader nods to each other and made them share or override some of their attributes. I decide to plug SSS Fast Skin to Mia Material X by connecting its out value to the Mia Material X additional color. To control the specularity on the skin I paint 3 maps one for reflection, one for the roughness and one for the glossiness. 

I learned a big a lot about Mia Material with this website.

 


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