One of the more difficult tasks you can undertake in many of today's 3D apps is getting texture maps, shaders, bump maps, and displacement maps to come together on a complex piece of 3D geometry to form organic objects such as plants or animals.

Very often the process involves several trips between an image editing app, your modeler, and its rendering engine. The process also probably involves a steep learning curve, an expensive 3D card, and an interface that is better suited for rocket science than artistic expression.

The folks at Pixologic want to make 3D art more accessible to artists and designers by designing a WYSIWYG interface for 3D work that allows the user to paint, model, and texture with the stroke of a stylus pen.

Some parts of the program work like a paint program, while other parts work like a 3D modeling app. Sometimes it works a little like a 3D version of Kai's Power Goo-you can smudge, stretch, push, or pull in 3D. ZBrush's greatest feature, however, is its realtime rendering of textures, lights, and 3D surfaces.

Sound too good to be true? Making a complex endeavor like organic 3D modeling an intuitive process is a bit like mixing oil and water, so there are a few trade-offs, as you might expect.

ZBrush is therefore by nature a bit of a dichotomous app—it has tools that are specifically designed for painting, and those that exclusively perform 3D modeling. Pixologic refers to these two functions as Pixol painting and sculpting.

The catch is that you can always paint but you can only work on one 3D object in true 3D at a time. You can save your 3D objects in ZBrush's proprietary Tool format so they can be reused later or exchanged with other ZBrush users. You can also export them as DXF or OBJ files (OBJ also exports a UV coordinate-intact materials library file and a texture file).

But when you attempt to use one of ZBrush's pixol-based 2.5D paintbrushes, that instance of the 3D object is automatically "stamped" into the scene. Once that happens, you can't change its size, rotation, position, or texture attributes, nor can you save it as a 3D object. You can, however, use ZBrush's pixol technology to add, subtract, or cut into the Z-depth.

What's a pixol? A pixol is a pixel that represents RGB information and also contains depth and material information. So if you begin painting from a blank screen, your paint brush applies color and texture. If you continue painting over the same area repeatedly, you begin to build a mound (or hole) of pixols that gradually forms highlights and shadows.

ZBrush comes with a wide variety of pixol painting brushes. There is the usual airbrush, plus brushes for blurring, cloning, etc. You can also use 3D primitives as brushes. ZBrush also comes with a fiber brush for adding 3D hair-like strands and a snake hook brush for creating plant branches, vines, etc.

You can also paint (or "sculpt," to use ZBrush's term) in RGB and Z on 3D objects by using the paint brush in the Transform palette. The brush works in a similar fashion as the pixol paintbrushes in that you can "paint" any combination of color, additive depth, and subtractive depth, but you can also paint masks directly onto 3D primitives. ZBrush also has some powerful 3D modeling tools such as inflate, spherize, bend, etc. However, like its paint tools, ZBrush's 3D tools only allow you to work in true 3D with only one 3D object at a time.

Although ZBrush has some nifty 3D masking tools, it doesn't have the kind of selection and masking tools you would find in Photoshop or Painter, such as the magic wand or Bezier drawing tools. It also doesn't include an alpha channel when exporting to a Photoshop file.

It can export a depth-cued alpha channel, but that's useful in only a handful of situations. ZBrush lets you create up to 32 layers, but all of those layers are merged when exporting to a Photoshop file.

ZBrush is now up to 1.13, but its documentation is still in the beta stage. The interface described in 0.90 of the manual bears little resemblance to the interface that boots up-some features have been added, others have been moved, some have been consolidated, while others have been replaced.

Version 0.95 of the manual is a better representation of 1.13's interface, but you have to download each section of the manual as a separate PDF file. And even then some features are undocumented.

ZBrush makes 3D fun, and may be a useful tool for print, Web, and game designers. But for video and motion designers, its absence of animation tools and alpha channel support, and limited 3D modeling tools, makes it of limited value.

3D animators may like its unique approach to modeling, but may not like its single-object limitation, the high poly count objects, and small texture maps it exports to their favorite 3D app.

ZBrush's inability to export an alpha channel or multiple layers, and its antialiasing problems handicap it for Photoshop compositing work. It also lacks video-friendly tools such as title-safe and nonsquare pixels. Video designers may find ZBrush useful for the occasional project, but for most of their 3D needs, they'll still have to rely on a dedicated 3D app.

Matthew Caldwell is a promotions editor at the Shop At Home cable and satellite TV network in Nashville, TN.