Referencing files into other files is a powerful feature in Maya.
When incorporated into rigging it allows for a way more non-destructive workflow.
This post will just be an intro to references for the uninitiated.
But first, let's review importation. We need to be sure we understand that so we can appreciate how referencing is different. And then we'll look at some of cool shit you can do in a reference workflow.
So I have two files here. Scene A:
and Scene B:
Most people's first instinct is to pivot the clavicles from the top of the sternum, which is only sensible as that's where the clavicles pivot from in real life.
And
if you were rigging a really, honestly, realistically proportioned
human character with corrective systems emulating the muscles and such,
that would be right. But 9 times out of 10 that's not the case, even if
you might think it's the case.
Look at this character. Looks pretty accurate to reality, no? A reality in which people have time to work out, but still.
There's an amusing Simpsons gag I'm very fond of. I'm sure you know it -
Some local children are watching a member of a film crew paint a horse in cow-print. One of the children inquires,
"Sir, why don't you just use real cows?"
"Because cows don't look like cows in the movies - you gotta use horses",
comes the reply, matter-of-factly.
And for good measure, another of the children then asks,
"What do you do if you want something that looks like a horse?"
"Hm... usually we just tape a bunch of cats together."
Knowing how to properly place points of articulation in a rig is about knowing when to use a cow and when to use a horse painted to look like a cow. That is - when to mimic reality and when to spit in its face.
Another way of thinking about this is the difference between simulation and emulation.