260 chapter 7 ■ Transpose, ZSphere Rigging, Retopology, and Mesh Extraction
- As you move each ZSphere joint, the vertices around it move relative to the position
of the ZSphere. This means that the shoulder sphere can potentially be assigned the
vertices of the chest and ribcage. This is a problem since it means the torso will deform
when the arms are moved. To resolve this, add ZSpheres for the ribcage. These spheres
will help capture the vertices of the chest and keep them from being assigned to the
joints of the arm, causing the torso to deform when the arms move (Figure 7.79). - Use the Move tool to shift the ZSpheres to fit inside the mesh from all sides (Figure 7.80).
You may need to adjust ZSphere placement as you test the rig. The relative placement of
the spheres to the mesh helps determine how the mesh bind is executed. If any part of the
bind is not working, simply click Bind again to turn it off and reposition your ZSpheres,
or add new ones where necessary to improve the bind.
There is an alternative method of adding ZSpheres to the rig. At the start of the process,
after you have clicked Select Mesh under the Rigging menu and loaded the model into
the ZSphere, turn off Transparency. Move the root ZSphere to the pelvis and start click-
ing to add ZSphere joints. This is a much faster method of laying out the skeleton, but
you will still need to move each joint into position from the side view. See the DVD for a
video of this process in use.- When the rig is completed you can test your bind by clicking the Bind button under
To ol → Rigging. When Bind is lit, the mesh will be linked to the ZSphere skeleton and
ready to pose. Before we start posing, let’s make sure our posed mesh will transfer to
the sculpted high-res subdivision levels. To do this, open the Tool → Adaptive Skin
menu and set the Density slider to the same number of subdivisions as the original
ZTool. Click the Preview button while holding the Shift key and your high-res preview
will appear. Make a small mark anywhere on the preview mesh with one of the sculpt-
ing brushes. This will cause ZBrush to remember your high-res preview and default
to it as you preview your posed mesh. Now use the Move and Rotate modes to pose
the ZSphere skeleton as you saw in Chapter 6 (Figure 7.81). Press the A key to preview
your mesh in high-res view with all the sculpted details applied (Figure 7.82).
Figure 7.79 Extra ZSpheres in the torso help maintain the
volume of the ribcage.
Figure 7.80 From the side view, move the ZSphere joints
into place.