88 chapter 3 ■ Designing a Character Bust
a polygon mesh created in a polygon modeling package—it does not carry multiple subdivi-
sion levels, layers, and other information. ZTools, on the other hand, are ZBrush models
that save polygons, multiple-subdivision levels, sculpted detail, subtools, color and texture
information, as well as alphas.
To load the model into ZBrush, choose Tool → Load Tool. This will open a file browser
dialog box. Browse to the Chapter 3 folder on the book’s DVD and select genericHead.ztl.
This will load the head ZTool file into ZBrush. There will be a new icon in the Tool palette rep-
resenting your imported model under User 3D meshes and 2.5D brushes.
By default, this new tool is already selected, so you can now draw it on the
canvas by left-clicking and dragging into the document window.
Enter Edit mode, and you are now ready to sculpt on the model.Before you can sculpt on the tool, it must be immediately placed in Edit
mode. If you were to stroke on the canvas again, it would only draw more
instances of the mesh on the canvas. As soon as the tool is drawn, enter
Edit mode by pressing the T key on your keyboard or by clicking the Edit
button at the top of the screen.Using Polygroups to Organize Your Mesh
When sculpting a character, it is beneficial to have the model organized
into easy-to-select parts to facilitate working on the ears or mouth
separately. I want to make sure that I can isolate the ears from the head
and manipulate the various parts of the ear without affecting the back
of the head. The same is true for the lips. Notice that if you try to move
the upper lip with the Move brush, often the lower lip will be moved too
since it is in close proximity and lies under the falloff of the Move brush.
Masking offers similar problems when you’re trying to paint a mask on
just one lip and not both.
Polygroups allow you to quickly and easily isolate parts of the model for sculpting.
Polygroups in ZBrush are simply selections of polygons that are tagged as being part of a
group. They are similar to selection sets in Maya. Polygroups are assigned a separate color.
In Figure 3.15 this stegosaurus has its parts polygrouped into different selections. The poly-
groups are visible when in Poly Frame mode. Enable
this mode by pressing Shift+F or selecting the PolyF
button on the Transform panel. The PolyF button
is also located on the right sidebar of the document
window.
Polygroups can help you organize parts of
your model into easy-to-access groups. Having
polygroups for the character’s ears makes it easy to
quickly show or hide the ear geometry to mask this
geo independently of the head. Any polygroup can be
isolated by Ctrl+Shift-clicking the group. This hides
all other polygroups. You can invert this selection
to show the hidden groups and hide the currently
active one by Ctrl+Shift-clicking and dragging aFigure 3.14 This solider was created
by Fabian Loing using some unique
masking techniques.
Figure 3.15 Model in Frame mode