When you use Zbrush in modeling, you definitely will use “Zremesher” to help you poly automatically, which is far more convenient than other softwares like Maya, 3DMAX and so on.
Generally, After making a rough shape that you want, you will use Zremesher so that you can get a clean model to carve then. Here is what you will get.
Looks good, the mesh is even and the density is proper. But if you then continue to carve and then export the model to maya and rig it, you will find most of the plug can not support your way of mesh.
Most of the rig plugs acquire this kind of mesh. All of the lines should around the eye and actually it is because this round line is much better for expression than the one made by zremesher.
Also, the mesh around mouth should be like it so that the expression could be smooth and easy to control.
So, if it means that we cannot use Zremesher to grow the mesh for expression rig? not exactly, we still can use it!
There is a tool named Zremesher Guides! You just need to open the menu and type in Z and R, then you will active this tool and use it as a pen.
Now, You just need to use this pen to draw the round lines around your eyes and mouth. These lines you draw will be as a guide to affect the way how zremesher grow the lines.
As the button circled in the picture, it can decide the strength. Larger number means zremesher will follow your guide line much more tightly, Lower number means the other way.
Then, after choosing the right strength, you just need to click the zremesher button and finally you will get a nice mesh that is good for expression rig!