One of the most interesting features of ZBrush is that we can re-import an object even though we have already started to add details, no matter at which level of subdivisions we’re working. The advantage is that you can modify a mesh with your 3D package and update it with ZBrush even though you have already added details to it.

Zbrush has a variety of modifiers but it is sometimes easier to make these modifications in another package.

Example : I like the shape of the skull but I want to increase its volume. I can do that very quickly in Maya by applying a lattice modifier (FFD) and reimport the mesh in Zbrush. To achieve that you only need to export the model at subdivision level 1.

To make sure OBJ files are imported in Maya without altering the vertex table of the object you need to set Create Multiple Objects to false (default value is true).

If you don’t do that, the model will be totally exploded at higher subdivision levels.

Level 1 is exported to Maya, the lattice modifier (FFD) is applied to deform the model where I want to and it's imported back into Zbrush at level 1. Subdivisions are increased to level 5 and we can see that the modifications are updated.

We can only modify the mesh, change selection sets or UVs etc but we cannot add polygons or vertices to the mesh otherwise the morphing won’t work.

The details of Taho are now finished in Zbrush are we are ready to export to Maya to rework the mesh.

Why reworking the base mesh ?

Details added in ZBrush, although interesting, are not adapted for animations or advanced rendering and so on. The low poly mesh was not detailed enough around the eyes and it is not looking very good now. To go any further with this model, we need to rework the mesh based on the one created with Zbrush.

Face groups imported in Maya. With this model is not really necessary but it is just to show you how it works for a full body for instance if it had more than 500 000 polygons. To rebuild the mesh, I use the Make Live function of Maya which makes vertices snap to a surface (vertices are literally glued to the surface and can only move on it). The problem is that Make Live makes the object transparent. It’s not easy to see the volume we are recreating so after enabling this function I make a copy of the object which I use as a reference.

Another trick is to hide the layer containing the Make Live object as the function is still active even though the model is hidden and I can work with only one visible instance of Taho. The last trick is to scale down a little bit the reference object using the Move Component which moves the vertices along the normal vector. The new mesh is therefore always on top of the reference.

To rebuild the mesh, I start by creating new polygons based on the edge flow of the model. This can be compared to edge loops, the most important edges in a mesh for animation or textures for instance. Too bad Maya doesn’t allow us to add colour to these particular edges.