AEC Tech News #98 (May 22, 2003)

21 May, 2003 By: Lachmi Khemlani

Overview of ZBrush

ZBrush is a unique painting tool that integrates both 2D and 3D effects in real-time, allowing you to paint an image with color, material, texture, and depth; push and pull your canvas; and even sculpt and texture 3D models. Like a 2D painting program, it allows pixel-by-pixel control of the image, yet it has a modeling and rendering engine like a 3D application. The target audience of ZBrush is anyone who needs to create 2D or 3D graphics, such as animators, computer artists, graphic designers, Web designers, and so on. ZBrush is available for both the Mac and Windows OS. ZBrush is not really an AEC application per se, and cannot fill in for dedicated conceptual building design tools such as Autodesk Architectural Studio, SketchUp, and Piranesi.

Architects, however, could potentially use it for conceptualizing innovative and intriguing building forms. ZBrush's synthesis of 2D and 3D functionalities allows 3D forms to be quickly and easily created and photo-realistically rendered, while avoiding the complexity of a regular 3D application. Priced at $399, the program is relatively inexpensive, and can serve as a good springboard for creative design ideas in any visual field.

The following section takes a look at Zbrush's key features that would be relevant to exploring conceptual building design ideas.

How It Works

The underlying technology of ZBrush is based on a different kind of pixel, called "pixol." Unlike a standard pixel that contains only the xy positions and RGB values, a pixol contains additional information such as depth, orientation, and material. Thus, a brush in ZBrush doesn't apply just color in the document window; it can include a texture instead of a color as well as a material, and has a depth value, in addition to the width and height values, that you can control. The Tool palette includes a variety of such 2.5D pixol-based brushes for achieving different 3D-like painting effects.

In addition, the Tool palette also includes several polygon-based 3D tools for creating a variety of primitive 3D objects such as cubes, spheres, cones, cylinders, rings, spirals, and helixes. Different modeling modes such as addition, subtraction, and cutting allow you to add to or subtract from the basic forms to create more complex objects. There are also an array of more sophisticated 3D tools for creating revolved objects out of a 2D profile, 3D terrains, 3D planes, 3D circles, polygon meshes, and so on. Transformation tools such as Move, Rotate, and Scale can be applied to modify an object immediately after it has been created; such transformations can be performed along a 2D plane as well as in 3D space. It is also possible to apply a row- or column-grid masking to, let's say, a cube object, and then extrude the unmasked areas (a process called "inflation" in ZBrush) to quickly simulate a building with openings. Another feature handy for architectural modeling is cubical skinning, which converts a 2D image into a 3D polygon-based object made up of tiny cubes. This object can be edited, applied texture and material, and exported into DXF or OBJ format.

Once a 3D object has been created and another tool is selected, the object ceases to be polygon-based and gets transformed to pixols, just like the shapes created with ZBrush's pixol-based brushes. Once it gets flattened out in this manner, it can no longer be moved, scaled, or rotated. However, it continues to have texture, material, and depth. Thus, you cannot use ZBrush exactly as you would use a regular 3D modeling application. The ZBrush document is also essentially 2D rather than 3D; thus, there is no concept of different views such as top, front, 3D perspective, and so on, as in a regular 3D application. 3D objects are automatically oriented based on where the cursor is located--if the cursor is over a 3D plane, the 3D object would be created in an orientation perpendicular to it.

Other ZBrush features that would be relevant to exploring conceptual building design ideas include a variety of sophisticated lighting and rendering tools. You can add four different types of lights to a scene--sun, point, spot, and glow--to illuminate it realistically. For each light, you can specify settings such as color, brightness, and falloff from center. Each light can be turned on or off as required; so can its ability to cast shadows. Since each pixol has depth, the scene gets automatically shaded based on the lighting configuration. Even though 3D objects get translated into pixols, they cast shadows just as they would in a full-blown 3D application. You can control how much ambient light is there in a scene, as well as specify global diffuse and specular light settings.

ZBrush has different rendering modes ranging from Fast to Best that allow you to control how much detail is rendered at a time. The Best Renderer mode shows all textures, materials, lights, and shading to a high degree of photo-realism. You can also add advanced rendering effects such as depth cue and fog, manipulate antialiasing settings, control environment reflection effects, and dynamically adjust brightness, contrast, and RGB levels. Several materials and textures come pre-loaded with the application; more can be loaded as required. Not only can you apply imported images as textures, you can also use simple painting techniques to create a texture within ZBrush itself that tiles seamlessly when wrapped around objects. Textures are automatically mapped correctly when applied to 3D objects.


Since this article was focused on the application of ZBrush to conceptual building design, it has only touched upon a fraction of what ZBrush can do. There are many more capabilities of ZBrush for its core target audience of artists and animators, which have to be seen to be believed. The interface is sleek and very innovative, with no menus at all. All tools are contained in palettes that can be expanded, collapsed, and even minimized as icons when not required. Packed with powerful features, the application seems a steal at $399. While not directly applicable to building design, you can certainly use it to explore creative ideas and have some fun in the process.

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