View Full Version : Rigging Quadruped Scapulas

02-21-2010, 03:25 AM
I'm working on learning the rigging of quadrupeds, and i'm starting with a big cat- a tiger.
In looking at the reference photos and videos, the big cats have a scapula (shoulder blade) that moves around a whole lot.
The front leg, when weight is placed upon the leg, forces the scapula up. I also see that the scapula swings back and forth during a walk cycle. Almost like it is aiming at the paw most of the time.
So I'm wondering what the best setup for the scapula movement should be.

attached is a pic of my bone setup. Let me know if someone can give me some good advice to get me started.

also, here is a good video of a tiger walking:

tiger walk (http://www.bbcmotiongallery.com/Customer/SearchDetails.aspx?searchText=tiger&type=Simple&footage=AllClipsExceptEntertainment&itemId=44e2a3fd-c900-4f6d-9637-f3e195c5e4ef)

02-22-2010, 03:26 PM
first of all, I would remove the extra joint, it is not really needed. Rigging is mostly about faking what is there. You can achieve most of the motion from wieghting. The M bone structure is working against what you are attempting to achieve, as it is holding the wieght for the scapula in place. By removing the bone and have a more inverted V bone structure then weighting the scapula 25/75 front leg/spine you get a much cleaner effect in most cases, you can then accent the motion and deformation with an infulence object, but that should not be necessary.

02-22-2010, 06:06 PM
Thanks, David.
I played around with the 'M' setup, and also reasoned that there's no reason to have that extra bone at the spine intersection.
So what rigging approach can I take that will make the scapula follow these two rules:

1. go up and down along its X axis direction

2. swing in an aim-like constraint when the paw translates forward.

My guess is: an Single Chain solver IK handle on the scapula joint itself. this locks the length of that scapula's joint chain.
then, below that, a normal RP solver along the two joints that form the backwards elbow.

I'm quite used to the auto-scapula setup that can be used for bipeds with a scapula on the back side of the mesh. It uses a scapula joint that is aim-constrained at a locator , with another locator as an up-vector object. Could that setup be used as a parallell for quadruped scapula setup?


02-22-2010, 08:00 PM
The Great Dane rig on highend has a good setup invovling this, you might have a look at that and try and reverse engineer it. I did something similar on a dragon rig and it worked fine.....nothing about it is "auto" though, which I prefer, but you may be looking for more of an "auto" setup, which you could probably add to it if you wanted.

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