CGTalk - Rigging a human rib cage in 3DS Max

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ja4161

11-18-2011, 07:59 PM

Hi all,

I need some help with rigging a human rib cage in 3DS Max. The rib cage should flex some but not separate at the joints. Each rib is separate and should attach at their respective vertebrae at the spine as well as to the sternum at the front. I tried using bones with a spline IK solver attached to the vertebrae and to the sternum, then skinning the rib to the bone. The effect wasn't great. My immediate thought was to link each rib directly it's respective vertebrae and then to the sternum with the sternum linked to a dummy at center spine. The problem is that 3DS Max doesn't allow linking of two ends of a single object to separate parents... at least not that I know of. Any help anyone could give would be greatly appreciated.

FYI, I do not know maxscript so that probably won't help much.

Respectfully,

John

dunkelzahn

11-21-2011, 08:56 AM

Hey there,

yeah, anatomically correct rib cages are hard to rig. The problem is, that the whole rib construction behaves more like a wicker basket and less like a normal hierarchy of bones.

I did one several years ago in Maya and it was hell to animate. Just did a mockup test and I guess your best bet in Max would be to create the rib bones by having them extend from the spine on. Then create a chain of bones/dummies from the clavicula on to the sternum. Now you can use constraints like look at/orientation and position constraints to have to rib end bone be influenced by the sternum end bones. This will allow you to close the circle on your bones hierarchy.

Adding some sort of IK system to each of the rib bones should allow for easy flexing there, while having your sternum constraints to hold the whole construction together.

Have fun, sounds like an interesting project there.

Chris

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