May 24, 2007

Unveiling the Art of Illusion

Author: Nathan Willis

Blender gets the lion's share of press among free 3-D modeling applications, but it is not the only player in the field. Art of Illusion (AOI) is a mature, GPL-licensed 3-D modeler with robust editing, animation, and rendering features, and it's a lot easier to use than Blender. If you haven't tried it, it's time you took a look at this recent SourceForge.net Product of the Month.

AOI requires a Java 1.4 (or newer) runtime environment, and the project recommends that you install Sun's Java Media Framework for optional support of additional animation formats. It can also use OpenGL rendering if your system supports it. The download page links to Linux, Mac OS X, and Windows builds, plus a platform-neutral package that should run on other flavors of Unix.

The latest Linux package is version 2.4.1, and weighs in at 7.4MB. Contained within is a .jar package and an installer script. You can install AOI anywhere on your system, including in your home directory -- a nice option for when you are testing it out initially. The installer creates KDE and GNOME menu entries in the form of .desktop files, and places a launcher shortcut on your desktop. It also creates an uninstaller in an appropriately-named subdirectory of the installation location.

Launch AOI and you will find another nicety under the Tools -> Scripts and Plugins Manager menu item: a GUI front end through which you can check for and install updates to AOI, and search for and install plugins and user-created scripts. Generally speaking, plugins bring new functionality to the app, while scripts automate functions already present. The line are blurry in AOI's context, though, as some scripts implement entirely new tools and object types.

Main features

So what exactly can AOI do? Here's a quick rundown (caution: list may be heavy on terminology). It can model objects with geometric, spline-based, and triangular-mesh-based definitions, and manipulate them with scripted behavior, boolean operations, skins, extrusion, and lathe turning. It can use image-mapped, procedural, and UV coordinate textures, procedural materials, and point, directional, and spot lighting.

Art of Illusion. Click to enlarge.

It can animate with keyframing, forward and inverse kinematics, skeletons, and animated textures. Finally, it can render with multiple cameras, using raster or raytracing, and apply filter effects, depth-of-field, antialiasing, caustics, subsurface scattering, and multiple global illumination algorithms.

Admittedly, the less experience you have with 3-D editing, the less that list will mean to you. Fortunately, the AOI Web site features a complete manual and an impressive set of tutorials to help you get up to speed. Such documentation is a high-priority feature for work and "production" apps; considerably more so than for media players and Internet tools.

The AOI manual strikes a good balance between explaining the nomenclature and exposing how to make use of it in the app. Few people will need the distinction between cylinders and cubes explained. But ample illustrations do help when explaining the difference between ambient occlusion and photon mapping. The AOI manual not only introduces both, it demonstrates them and shows the effects of the various parameters tunable within the app.

The tutorials will also prove useful to first-time AOI users. Some of the basic tutorials are several years old, but the app's interface has not changed enough to make them outdated. In most cases, the only differences are the addition of more options or parameters in features like texture and material creation.

Competition is good

Blender has several editing features that AOI does not, such as 3-D and vertex painting, softbody and fluid simulation, and NURBS. But don't be fooled into thinking that it's a one-sided battle. Take a look at CGSocietycomparison of 3-D modelers and you'll see that the two open source programs rank about the same in most categories. Both are a few features behind heavy-hitting (and expensive) proprietary packages like 3ds Max and Houdini, but they hold their own.

AOI beats Blender hands-down on the interface front. Despite improvements in recent versions, Blender still has a long way to go here. Since it is a Java app, AOI may not natively look as slick, but its object manipulation, texture, and materials tools demonstrate that features and usability are not mutually exclusive.

For example, all commands are accessible from the menus, which helps immensely when you don't remember a shortcut. The main window is always used for scene and object editing; when needed, complex but secondary tasks like procedural texture editing come up in their own windows, thus keeping the main interface uncluttered. The buttons, labels, menus, and text boxes are all standardized, meaning you don't have to guess whether a field is an editable parameter or an uneditable label.

You can get started quickly with Art of Illusion, even if you have no experience with 3-D modeling. AOI is not as simple as Google SketchUp, but it comes close on the basic construction and object manipulation fronts. More importantly, you are not limited to basic construction: powerful features are at your fingertip, on par with the best of the open source 3-D applications.

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