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MacUser Review April 2007

Issue: 23 9

Cheetah 3D from German developer Martin Wengenmayer just keeps getting better, and version 4 has taken the 3D community by surprise with its new features and overall polish. The first thing you'll see is the slicker new interface, with new icons designed by Cheetah guru Frank Beckmann.

Most of the improvements have been made in the area of animation, although other areas of the program have been tweaked as well. In Modelling, for instance, the Subdivision Surface algorithms have been rewritten to be multi-processor aware, making complex organic modelling smoother and more responsive on multi-processor Macs. This is an optimisation that even the big programs like Maya don't have.

Also improved is the Transform tool. This is now a single 'widget' containing the Move, Rotate and Scale operations in one tool. This generally works well in practice and is a big improvement over the separate Transform tools in previous versions. Another long-awaited feature is the ability to multiple-select objects in the Browser (contiguous and non-contiguous) and to group and ungroup the resulting selections. There's also a useful new Ruler tool, allowing live readouts of object dimensions.

On to animation. The first new featureis morph targets. A morph target (which is added to an object via a tag) simply represents a different state of the mesh of an object. So a character's face can have a 'base' expression from which you can derive other expressions (happy, sad, angry) from the base mesh using Cheetah 3D's modelling tools. Each new expression can then be saved as a morph target, allowing the mesh to blend seamlessly between the different expressions. You can also set the amount of the morph from 0-100% using sliders accessed via the Morph tag.

The biggest change in Cheetah 3D's animation system comes with the introduction of skeletal deformations.

You can now build an 'armature' of joints for a character simply by clicking and dragging out a set of 'bones'. Shift-clicking enables you to build non-contiguous bone chains. As you build your character, the bones are automatically correctly grouped in the object browser.

Once the skeleton is built, it needs to be attached to the mesh it will be deforming - that is, your character. This, like a lot of things in Cheetah, is accomplished by tags, in this case the Skeleton tag. Once attached to the mesh, the bone armature can be simply dragged and dropped onto the Skeleton tag's Properties window. This then binds the mesh to the armature. Now, when the bones are moved or rotated, the mesh will deform with it. Again, the new Transform widgets show their worth here.

Cheetah does a pretty good job of automatically setting up each bone's influence and fall-off, and this can be seen via the mesh weighting colours (red for 100% influence, yellow for 0%). However, you also have the option of fine-tuning bone influence by painting the mesh weights directly onto the surface using the Vertex Weight tool.

As it stands, your character is now ready for posing and animating, but you can further fine-tune the skeleton by the addition of IK (Inverse Kinematics) tags to particular joints, enabling them to affect joints further 'upstream'. This gives a more marionette-like control over the character.

Finally, you can apply Constraint tags to the joints to limit them to realistic ranges of movement. While it ships with an example walk file, it would be nice to see a fully rigged skeleton included as a base object type, to make this setup easier.

Cheetah 3D 4's animation control tools also incorporates a Pose Manager. You can take snapshots of individual skeleton configurations, or poses. These can then be set as keyframes along the Timeline, and Cheetah will smoothly tween between the poses. In this way, poses can be reused and shuffled, saving considerable time and effort. In a similar vein is the Take manager, which records a range of movements rather than a static pose (that is, a Take would be a movement delimited by a Pose at either end), although a Take could equally well apply to a camera's movement during a fly-through.

Although there has been a slight price rise to $129, this is more than offset by the greatly increased functionality in version 4. Users of version 3.x of Cheetah 3D can also upgrade for only $59.

By Tim Danaher, MacUser magazine

 

Modelling with Cheetah3D

Skeletal deformations in Cheetah3D

"The Subdivision Surface algorithms have been rewritten to be multi-processor aware, making complex organic modelling smoother and more responsive on multi-processor Macs. This is an optimisation that even the big programs like Maya don't have."