Skin

So, the skin has been a matter of balancing all texture into a shader it was surprisingly easy to setup. Quiet frankly, I was really impressed by the beauty of this Marmoset global illumination system.

Subsurface material came out better than I expected. Of course There are artifacts, depending by the subsurface simulation but, what the hell, it is really good!

I spent a lot of time painting the diffuse map of the face. I overlapped photos of the actor, together with photos of 3dsk website. I lost the count of time I spent trying to blend those photos (that is why having good references is so important, when it comes to the portrait of a so famous actor…)

After a pass of texturing in Mari. I extracted my diffuse in Photoshop, were I kept working on it, adding details, tweaking the overall color, according to the other channels an the way the shader was coming out.

Now, about the skin shader, there are different schools of thought about how to set it up properly.

In my opinion, what really gives the feeling of a good skin is the correct balancing of these channels:

glossiness, translucency, scatter, and fuzziness.

All the other channels were easy to set up and the diffuse was important just to make him resemblant to the actor but, in term of shader balancing, an easier texture, based on larger portions of colors would have worked well enough too.

I started applying the normal map extracted by zbrush and the diffuse (with the help of a detail normal map for the skin pores). Then I placed the reflection value to 0.4%, which is a good starting reflection value for the majority of materials in nature, metals excluded.

Even if skin is a complex material I have no reason to think that muscles, bones, blood, have a so much different index of specularity, and dirt, or sweat, on top of it, should not affect it neither.

Then I had to spend time tweaking the other textures.

Glossiness is the most important channel because it gives all those variations of grease, and oil that is common on all faces and all materials could have variations of glossiness, depending how polished is the surface of the material. It has nothing to do with the chemical property of the material itself and that is why, unlike the specularity, you cannot find an index of glossiness, or roughness online. Also, having a fixed value for the specular helps a lot when it comes to balancing your glossiness channel. You’ll be in time to add some specular variation later on, if necessary.

Tip of the nose, areas around the nostrils, and the forehead are more oily than the cheeks, chin and neck. Translucency simulates the light filtering through the thinner skin, showing that pure bloody red color. I created a maks, in Substance Painter, defining the areas where It should have been more evident: ear tips and sides, but also nose tip and nostrils borders.

I left some translucency in the cheeks as well, but at a lower level. This gave some warm tone according to the light. Scatter channel simulates what happens when lights get to a deeper level onto skin. Marmoset has a depth slider expressed in millimeters.

I set up mine at 1.5 mm (initially it was deeper, but I think, on this software, it’s too sensitive). Scatter texture simulates the color of the skin at the subdermal depth. Fuzziness defines how much the light gets diffused all over a furry surface. Faces, but skin in general, is covered by fur, but in some areas where beards does not grows, it much thinner and less evident.

Either way there’s a subtle layer of fur, and that affects the way you feel the skin material. It is an essential channel if you want to obtain a decent skin. It should not be underestimated. Last, I used the cavity and ambient occlusion maps to get some better result. You should not exaggerate with these ones because they often give your asset a dirty look. Like if it was covered of dust.

Shot

Wine has been a handful. Marmoset Toolbag is not able to render a proper refractive material, yet.

I was forced to find a way to mask some of the artifacts he was producing. In order to get a glass-refracting material, you have to scroll your shader to the bottom at the Transparency palette and set it to Refraction.

I searched for a physical index of refraction for the glass, online, but that was not the right approach with this software. A real refraction value depends on the thickness of the material, AND the material itself, but right now Marmoset, being a realtime render engine, can only make a simulation of refraction so, any physical value would give a weird result. I’m sure we’ll get there, though.

In the meantime you’ll have to find the value that works better for your asset. Anyway, here’s some trick to get a better result. First, when you model your refracting material, always rememeber to make a closed model, with a proper thickness. Also, after you finished your model, duplicate it and invert the normals of all your polygons. Then export both your models.

In Marmoset you will apply your refracting material to both your overlapping meshes, and, turning on and off the second model you’ll notice that there are much more interesting reflections on the final result. This is because Marmoset doesn’t have a proper Dualface material. You can deactivate the Cull Back Faces, of course but, exactly like for the hairs, this doesn’t gives the result you want.

Duplicating the model give better result, and offers more opportunities. In my flask, for example I had one material for the external mesh and one for the flipped-normals one. This way I was able to paint the shade of wine along the surface of the flask just inside the flask. With only one material this would have been impossible.

The same operation I did for the wine. What it gave me the feeling of a decent wine was the refractive texture I manually painted. Wine is not completely refractive. It is actually pretty opaque, so I turned to black the biggest part of the refractive map, leaving some grey tones along the border, and the surface.

I added some noise into the texture, so that it looks like more organic.

I used the Subsurface Scatter, again, for the diffusion. Now, you should know, when the Refraction is on, it doesn’t matters if the mask is completely black (non-refractive at all), some is still happening in the shader, and reflection comes out in a different way. Originally, I had a unique model for rings, glass, and flask, but I was forced to split them when I noticed the metal ring reacting to light in a weird way. As soon as I split the model this was suddenly fixed.