Hybrid texturing:

Now that our Uvs are laid out and we have extracted our Normal and Displacement maps, we can export the head mesh via the FBX file format and start compositing our Material in Substance Designer. In this video below, I show the first steps of creation where I import my model, extract some maps such as Ambient Occlusion and Curvature. Then I composite these maps with basic image operations such as coloring a grayscale images with the "Pick Gradient" feature in the "Gradient map" node and so on...

Now that we have the base color, I can start to add some details such as freckles or skin color variations.

Here, I simply used a Black&White noise that I edited with a "Levels" node by lowering the High entry key, then I scaled up the pattern with a "Transformation 2D" node. After having set up my noise texture, I can colorize it with a "Gradient map" node and finally blend it with my main texture using "Soft Light" in order to give some color variation to our skin and start to give some realistic skin imperfections to our Material.

I continued the same detailing process by adding some freckles. In this case, I used the "Fractal Sum Base" preset, colorized it with a brown/orange color and blended it with the "Darken" blending mode. In this case, I created a new SVG resource and painted the areas where my freckles are going to blend with the skin texture as a mask for the blend node.

At this stage, I am starting to bypass my graph in order to create all other outputs such as Specular, Epidermal, Subdermal maps and so on... This is where the non-linear approach of Substance becomes really handy, as I don't need to worry too much about each maps and modify them one by one when I want to add details or make some retake on the Diffuse texture: All of my material's maps will update at the same time.

I am now reaching the final stage of texturing where I hand paint the finest details. Here I created various Bitmap nodes in which I painted details such as beauty spots, three layers of make-up for the eyelid and lipstick.

For each creation stage, I create a bunch of parameters that will allow me further on to customize my texture directly within Maya during the Shading and Render setup. For example, I exposed intensity and color of the eyelid make-up and lip stick. I also exposed various node controls such as the blending amount for freckles or the hue, saturation and contrast of the base skin layer.

My material is now fully completed, the Substance material outputs nine texture maps: Overall Color, Normal, Specular, BackScatter, Diffuse, Epidermal, Subdermal, Reflectivity, Gloss and Roughness. All of these maps are linked together, and the parameters that I exposed in Substance Designer will affect the nine maps at the same time.

From SD, I selected my Substance package and published it as a Substance archive (*.sbsar file), and then went back to Maya.