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Yet Another Shoulder Rig


OdinsEye2k

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Well, I got some crazy ideas at the Southeast user's group meeting that I put together along with a couple tricks of my own.

 

Weight mover did a majority of the work - my tests with Thom were transfered directly to the main model.

 

There are three bones overlaying the 'bicep' position. The largest is the main control bone that drives the full shoulder. Next is the orient like bone (with Store Roll off - thanks guys, didn't even know that was there!), with the actual geometry bone as a child. That bone has a Roll Like to the controller. This is important because bone weights apply to all three dimensions - the bone structure is what does the decoupling so that I can use the whole arm for a Z twist while only using the shoulder for aiming.

 

My tricks were to add Expressions. Volume is conserved (as much as I could) in the armpit by adding an Expression to the arm pit fan (the dangling one by the pit) scale, so that the bone would stretch out as the bone rotated, preserving volume. Expressions also served to separate the axes of rotation on the fan.

 

I learned recently that my Quaternion/Euler conversion problem was actually not a real problem - Hash expressions convert automatically! The only trick is that when you click a channel to get a property (as in |..|Rotate.X), you have to get it from a Translate channel and replace "Translate" with "Rotate" - for some reason clicking the Rotate gives bad syntax.

 

If you got all that (or didn't), take a good look at:

 

http://www.prism.gatech.edu/~gtg724n/maintest.mov

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  • Hash Fellow

It looks generally good. I like the relative simplicity of it

 

My only reservation is that the joint where the upper arm rotates at the shoulder appears unnaturally located... too far out. Would this scheme still work if that joint were moved farther in?

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Like robcat stated, looks good in general, but the joint seems out of place. The other thing I noticed is at the end of the clip, when the arm moves down and forward slightly, it looks very unnatural, maybe cause by the joint placement. Can we see it from another angle with the arm forward?

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The only trick is that when you click a channel to get a property (as in |..|Rotate.X), you have to get it from a Translate channel and replace "Translate" with "Rotate" - for some reason clicking the Rotate gives bad syntax.

Oh my gosh! I thought I was the only one having that problem.

I've been living with that peculiarity for like 6months now!

thanks for sharing that!

 

Mike Fitz

www.3dartz.com

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Like robcat stated, looks good in general, but the joint seems out of place. The other thing I noticed is at the end of the clip, when the arm moves down and forward slightly, it looks very unnatural, maybe cause by the joint placement. Can we see it from another angle with the arm forward?

 

At first, I thought it was a render artifact (having all these weights makes the rendering - both final and shaded - act a little funny unless I reload the project), but I looked closer. For some reason, the expressions on the shoulder are popping at that moment. Strange, because they don't cross any kind of axes or singularity points or anything like that.

 

So close, kids, so close....

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Hey Bjorn, looks great, except now it looks like there is no Z rotation at all in the shoulder?

 

I think the shoulder to elbow twist needs to be dispersed along the bicep tricep region a little bit more....

 

Mike Fitz

www.3dartz.com

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Still hacking the popping problem.

 

I added a volume preservation fan on the shoulder (helps a little), but I just decided to smartskin it into roundness (could theoretically add more).

 

Also, I brought the joint in ever so slightly (just enough that his hands are naturally almost touching his hips - when I make the woman, her hips will violate this space).

 

For your help folks, you now get two movies of motion:

 

http://www.prism.gatech.edu/~gtg724n/maintest2.mov

 

http://www.prism.gatech.edu/~gtg724n/maintest3.mov

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Bjorn,

 

Looking good!!

 

Just curious about the location of the shoulder joint though.

It looks like it is too far out.

The shoulder ball socket rests under the point at which the Clavical ends.

(see attached)

 

Can we see a straight on shot with Bones?

page059.gif

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Hi Bjorn,

 

I fixed the problem you reported on AM:Reports of clicking on the X, Y or Z sub drivers of a rotate driver while editing an expression.

 

For your second problem involving a jump in the expression behavior. This is due to the automatic switching of the euler order which is used to decompose the rotation into 3 values. It is switching between YXZ order and XYZ order, on the fly, and causing the jump. In version 12, I have added a new property to the Bone called "Euler Order". Most users will never need to modify this, but for your expressions, you may want to change it from "Automatic" to "YXZ". That should remove the jump.

 

Thanks,

Bob

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Hi Bjorn,

 

I fixed the problem you reported on AM:Reports of clicking on the X, Y or Z sub drivers of a rotate driver while editing an expression.

 

For your second problem involving a jump in the expression behavior. This is due to the automatic switching of the euler order which is used to decompose the rotation into 3 values. It is switching between YXZ order and XYZ order, on the fly, and causing the jump. In version 12, I have added a new property to the Bone called "Euler Order". Most users will never need to modify this, but for your expressions, you may want to change it from "Automatic" to "YXZ". That should remove the jump.

 

Thanks,

Bob

THANK GOODNESS!:)

 

Mike Fitz

www.3dartz.com

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Most users will never need to modify this, but for your expressions, you may want to change it from "Automatic" to "YXZ". That should remove the jump.

 

Thanks,

Bob

 

OOOOOhhhh! Shiny! A new button just for me.

 

Bob - Thanks a million for that - I was actually about to ship a huge project with all of that data for you to look at.

 

And it explains why it was so darned hard for me to figure out what the heck was going on when I was trying to do the math by hand.

 

Sneaky, man. Sneaky. B)

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