Animation Interface
Common actions, such as navigating and setting keys are easily accessed through keyboard commands (which now can be set to match those in your other favorite 3D applications), and MotionBuilder keeps commonly needed tools within arm’s reach, although this can result in a cluttered screen as windows multiply.

But MotionBuilder’s interface puts tools conveniently close to the surface, although many commands are in obscurely named pull-down menus on the various palettes, and there is a considerable learning curve in figuring out where functions live.

MotionBuilder’s animation interface is very intuitive, and can do many things that would be difficult to achieve in other applications. For example, setting keyframes is straightforward, but if you want to constrain a character’s feet to a bicycle’s pedals, a new feature in MotionBuilder 6 lets you quickly create handles, which constrain multiple IK effectors together. Set up a handle on the left pedal and left foot and, when you rotate the pedal’s crank, the pedal and feet automatically follow. It’s similarly easy to pin a character or prop’s joints in position, such as when a character grabs a chair to sit down. Another new feature in MotionBuilder 6 lets you create auxiliary pivot points for effectors or joints. This would let you animate a hand on a piano’s keys rocking back and forth between the tips of the thumb and little finger, while the character dances around; or to have a character’s feet roll, first from the heel then from the ball of its foot, as it walks.

A new feature in MotionBuilder 6 lets you create auxiliary pivot points for effectors or joints. It allows you to quickly define and animate multiple independent rotation points for any IK Control rig effector.

Speed to Screen
MotionBuilder is also exceptionally fast. From rigging a character to creating poses and keyframes, importing and attaching animation data, setting up multiple shot cameras in its non-linear timeline and to scrubbing through and playing back finished animations, it is remarkably efficient in getting animation done quickly. One of the keys to MotionBuilder’s success is its realtime display engine that lives up to its hype. With even a modest Open GL graphics card, you can load a fairly heavy 3D character mesh and a handful of props, and still manage to play your animations on the fly at 30 or 24 fps.

Part of this performance is owed to the fact that MotionBuilder’s rigs are fairly simple. They’re not busy calculating muscle deformations or the interaction of double IK/FK rigs, which are the norm in film work. MotionBuilder’s character rigs are more on par with those in a video game using simple smooth binding and a very limited number of influences between joints and skin vertices.

Rigging
To set up a character in MotionBuilder, you begin with the rig. MotionBuilder lets you set up a character rig from scratch, say if you’re working with a mesh imported from a 3D model library, but Alias recommends setting up a skeleton and skin weighting in your 3D modeling system before importing to MotionBuilder. If you have set up the joint chain on your character with a specific naming convention, MotionBuilder will automatically generate a complete IK/FK rig with a couple of mouse clicks, and create extra in-scene effectors for joints that aren’t part of the standard naming scheme. Skeletons that use non-standard naming can still be rigged in MotionBuilder, but you’ll have to manually assign each of your skeleton’s bones to one of MotionBuilder’s standard rigging outputs. Rigging alone can save hours or days of work on a single character, and can quickly justify the price of MotionBuilder.

Several all-purpose 3D animation systems, including Maya, 3ds max and XSI, have sophisticated tools for binding and weighting a character skin. MotionBuilder lets you select points and apply weights, but this is not nearly as elegant, fast or friendly as a 3D painting system that lets you visually paint weights where you want them. This is one place where MotionBuilder needs work. While I have no qualms about a highly specialized $1,000 or even $4,500 workhorse tool, I at least expect it to have a comprehensive toolset within its particular niche. Also, some of my favorite character modeling tools, such as Luxology’s modo and Nevercenter’s low-cost Silo, lack joint creation and skin weighting tools of their own, and models from commercial libraries are also typically not jointed or weighted, which means that eventually you’ll have to work with MotionBuilder’s stripped-down skinning features, whether you like it or not.

Once the rig is created, it becomes accessible through MotionBuilder’s standard selection widget that diagrams a human, or quadruped, with selection points at all the FK joints. You can also switch this panel to a view of the right and left hands or feet for working with finger joints or foot bones. The selection widget lets you select one or more joints to act on, which is important for setting keyframes, as well as when you want to paste in motion from other characters, from a library of motion clips or from motion capture data. You can choose to paste or attach data only to the selected joints, or to the entire body.