Why recalculate bone roll angles?

I’m rigging a character with the new armature system and I was using the limit local axis option for a finger. But the bone axes are not lined up and down with the finger after I had recalculated the bone roll angles. Originally I was just going to limit the z-axis so the finger would not hyper-extend. But the bones aren’t lined up to do that.

My question is: what does recalculating the bone roll angles actually mean? What does it do? Is it necessary, or can I rotate the bones manually in edit mode so that their axes line up the way I want them to line up?

Thanks,
LGM

The only problems you might have are either when you copy and paste a flipped pose or after mirroring one side.

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Oh. Well, I don’t mirror bones when I rig, and I think I can survive without being able to copy and paste the flipped poses of his fingers.

Thanks, Fligh %, I’ll just go ahead now and rotate those finger bones.

I’m still curious, though, as to what recalculating the bone roll angles means.

LGM

It aligns the Z-Axii of all (calculated) bones. I suppose it doesn’t have to be the Z axis, depending on which view it was added, or maybe it’s always the same. Give Theeth a bell and you’ll get the exact answer.

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Thanks, will do.

LGM

IIRC, it tries to realign the Z axis of each bone with the Z axis of the armature object. It might do some fucky stuff like trying to minimize roll difference in a chain, but I’m not sure.

Martin

Okay thanks. I just applied rotation to the armature as an object and then recalculated the bone roll angles and they all jumped again. That’s neat to know. Looks like I can just rotate them to my purposes and it’ll be fine.

LGM