The above view of the hypergraph
shows a simple 3 bone IK chain. The dashed red line on the left
hand side indicates the bones that form the chain itself.
When you create an IK chain in Maya,
you will also create two additional nodes, an IkHandle and an
IkEffector. The effector is basically a transform that determines
the end position of the IkChain. The IkHandle represents the start
of the Ik chain and is also the parent transform of the Effector.
One common additional element you
may expect to find is a pole vector constraint. When an animator
sets up an Ik Chain in maya, it often has a tendancy to bend the
wrong way. To fix this, a locator node is usually used as a guide
to determine which direction the elbow should bend in.
note, a locator node is not
the only object that may be used. Often simple mesh shapes are
preferred by animators since different shaped controls can give
a visual aid as to what part of the model they control. It should
not really be of any concern since it is actually the transform
that is important for the Pole vector constraint. If however you
find a shape used as the contraining object, you should easily
be able to prevent the shape from being exported.
If your intention is to re-create
the animation using an Ik Rig and animation curve data, then be
very aware of the way in which your art team are rigging their
models. Often Ik chains are used along-side multiple point, orientation,
scale, parent and/or aim contraints. You should really handle
these contraints types if you want your Ik chains to animate exactly
as the animator intended.