154 chapter 4 ■ ZBrush for Detailing
- Now you need to fill the object with gray. Click Color → SysPalette to open the system
color picker. You want to select 50% gray for your base texture. Select the RGB value
128 128 128. This value is read by ZBrush as neutral and consequently there’s no
displacement. When you paint on this material with shades of white and black, it will
render as a bump for white and a recess for black. - With 50% gray as the active color, click Color → Fill Object. This sets the object base color
to a neutral gray. Any other shade you paint on top of this will read as sculpted detail. - Make sure the Bump Viewer material is the active material. Under the Transform
menu, turn off the Quick button to disable Quick Render mode. This mode can create
artifacts in the bump display.
You will now use the standard brush and some skin alphas to create sculpted detail
entirely with color and the Bump Viewer material. You can do this with standard polypaint-
ing, which will paint detail as crisp as the underlying polygon count will support. For many
applications, this approach works just fine. You can, however, utilize HD geometry to get
the absolute sharpest texture resolution from your resulting bump map. I will often paint
into HD when I know I need to extract multiple high-resolution texture maps from a single
ZTool. Follow these steps to paint bump detail onto the character: - From the Tool menu select the standard brush. Turn off ZAdd and turn on RGB.
Make sure that the M modifier is also off. Select a Freehand stroke and Alpha 42.
From the color picker, choose black. We’ll use RGB intensity to control how strong
our stroke appears instead of ZIntensity.
As you work, if you want to erase simply paint back in the same 50% gray color.
You can switch between the main and secondary color swatch selections with the V
hotkey. You can blend your color with the Smooth brush, but be sure to turn off ZAdd
while holding Shift. - Make sure you have no layers on the ZTool. Divide the model a few times with the
Divide HD button under Tool → HD Geometry. - Mouse over an area and press the A hotkey to preview HD mode. When the HD region
is active, start sketching in your texture for the front view (Figure 4.72). - If you want to fade or erase strokes, simply select the same 50% gray value and paint
over your previous strokes. Remember that you are painting color, not adding or sub-
tracting to the geometry. The Bump Viewer material is giving the impression of fine
details.
You can use the Bump Viewer material technique shown here with or without HD geom-
etry. The benefit of HD is that polypaint will be sharper the more underlying polygons
there are to support it. The denser the mesh, the higher resolution the final texture map
you extract can be. A single head divided into 1 billion polygons can support a texture
map of 500 million × 500 million pixels.You will notice that the strokes of color render on screen as sculpted strokes.
No geometry is being altered—this is entirely a rendering effect. The maps you cre-
ate from this process can be rendered in ZBrush, Maya, 3D Studio Max, XSI, or any
other 3D package that can use bump maps. Figure 4.73 shows the effect of the bump
map details as seen inside ZBrush. None of this detail is sculpted—it is all a result of
the painted bump map rendering on the Bump Viewer material in the viewport.