I will be showing my workflow for adding skin and pore details to my characters using the wonderful maps at texturing.xyz. There are many different ways you could go about this process. My two main workflows are:
Applying the skin details through projection with MARI and sending the generated displacement back into ZBrush or Maya
Since there are already plenty of tutorials on the first workflow at http://texturing.xyz/pages/tutorials, I will be showing how I apply details directly in ZBrush using a personal sculpt I worked on of E. Honda from Street Fighter.
The first thing you want to do is consider how close up we will be seeing this character. This decision will ultimately affect your UV maps as well as your texture resolutions.
I knew ahead of time that I wanted to get fairly close up to the face of this character. This meant that I decided to dedicate a whole UV tile for just the characters face alone. I also had to determine the resolution that I would be rendering in in order to determine how large my maps were going to be. In the end I decided to use 4K x 4K texture maps.
ZBrush can only handle subtools that are under 100 million polygons. This was not enough resolution for me to get the details I wanted. I decided to separate the subtool into parts based on UV tile. To do this you have to:
Set your subtool to the lowest subdivision level
Go to Tool>Polygroups>Uv Groups (This will polygroup your mesh based on its UV tiles)
Then split the mesh by going to Tool>SubTool>Split>Groups Split
Now that our character has been divided into separate parts, we can proceed to subdivide each part into the required amount of polygons. Because I settled on using 4K maps, I have to subdivide the head to a resolution of somewhere around 16 million polygons in order to fully utilize the resolution space. The same thing goes for other parts of the body, unless of course you don’t mind having less resolution on those areas.
With all the prep work done, we can now go about sculpting. Using the standard brush, set your stroke style to DragRect. This stroke style lets you draw out single instances of an alpha directly on the surface of your mesh. Before you begin sculpting, make sure you create a new layer in zbrush. This way you can always erase any mistakes you made when placing the alphas. You can use as many layers as you want. I prefer to have a layer for all the TexturingXYZ alphas and another separate layer for hand sculpted pores and wrinkles.
I store a morph target before I begin sculpting. You can find this under Tool->Morph Target->StoreMT. Every TexturingXYZ alpha set comes with a JPG that shows you the corresponding position of each Alpha on the face. It looks like this:
I like to start of with the area under the eye. I set my alpha to Alpha 24, which corresponds to that particular area. I like to keep a shortcut of the folder where all the TexturingXYZ alphas are located in the ZBrush directory so I can always access them easily through LightBox.
This can typically be found under the install directory of ZBrush->ZAlphas. Always remember to set the Mid Value of your Alpha to 50, otherwise you will get an unwanted border where you drag out your alpha. This setting can be found under Alpha->Modify->MidValue. Next I simply drag out the alpha on the surface of the mesh, always keeping in mind that the direction the mouse drags is where the top edge of the Alpha will be placed.
I drag from the bottom of the eye up towards the brow. Getting the Alpha to be placed exactly where you want it to be may take some trial and error. If it’s not where you want it to be, just undo and re-place the alpha. Any areas on the mesh that the alphas was placed where I didn’t want it be placed, I paint away with the Morph brush (assuming you went ahead and stored a morph target before you began sculpting). If you forgot to store a morph target before placing the alpha, you can always:
Disable the layer the alpha was drawn in by pressing the eye symbol
Store a morph target
Re-enable the layer by pressing the “record” symbol
You can also store a morph target after placing an alpha so that when you paint away overlapping areas where another alpha has been placed. I repeat this process all throughout the face, always looking at the provided reference image to make sure I’m placing alphas in the correct location. I generally like to be heavy handed with the placement as it tends to get washed away by the SSS when it is rendered.
Be patient with the work and don’t rush it. Pay specific attention to the direction of the pores and always be looking at reference.