Cavity Masking

From ZBrush Info

Finely detailed surfaces in the real world often show a color difference between their raised areas and their lowered areas, whether through actual color differences, or because of ambient occlusion.

Consider the surface of a brick. We all know that a (stereotypical) brick is a sort of reddish-brown, but of course it isn't. Any brick that's been out in the weather for any length of time will accumulate dirt in its pits and grooves, and those areas will actually be dark gray or black. A texture map for the brick should reflect this.

ZBrush's new cavity masking feature makes it easy to accomplish this sort of painting (and some other similar effects, too). Put simply, cavity masking allows you to automatically mask out fine recesses (or fine high points) as you work, so that your work affects only the high points (or low points) of the model's surface.

Even better, ZBrush lets you work with cavity masking in two ways:

• In the first, you simply paint (using a 3D brush and the new Polypainting feature of ZBrush) with cavity masking for brushes turned on. Cavities are automatically calculated as your brush passes over the surface.
• In the second, you can mask your entire model, and then work with the masked model. This is the same as directly painting a mask onto a model and then sculpting or polypainting the surface of the model; the difference is that cavity masking gives masks that you could never produce by hand.

Let's see how all this works.

Using Cavity Masks with Brushes

ZBrush's new Brush Palette contains new controls related to cavity masking. Use CavityMask (which turns cavity masking on or off) and CavityInt (which controls the strength of the masking effect).

Left: High-resolution wrinkled mesh. Middle: Masking as produced using the cavity mask features. Only the low areas of the wrinkles are defined. Right: A quick polypainting stroke with cavity masking on (though the mask is not visible.) The stroke colors only the high areas of the skin. The mask prevents the grooves from being affected.

Adjust the CavityInt to increase or decrease the effect of the mask. A setting of about 80 to 90 tends to produce the best results.

Cavity Masking Controls

Cavity masking is a ZBrush 3 features that permits automatic masking of cavities (eg. wrinkles) or raised areas (such as scars). This makes it easy to exaggerate such features, paint different colors onto them (such as a mixed red for a scar), and in general quickly achieve other affects that couldn't otherwise be done in a reasonable amount of time. For full details, see the Cavity Masking page.