So I have been reading Tony Mullens book, and have been experimenting more with armatures. I wanted to use a bone to rotate an object. I notice that if I don’t use an armature, and keyframe, I get RotX/Y/Z, but if I rotate a bone and keyframe I get QuatX/Y/Z/W.
What are QuatX/Y/Z/W, and why are there 4 of them, even though I am doing a simple rotation in 1 axis?
I had actually seen that, but I was hoping for something really simple. I’m still a little confused, when I rotate the Z axis of the bone, no other motion, why does QuantW change?
I’m out of my depth here but I’ll try. When key rotations for a simple Object it needs only XYZ references relative to a) the Scene (Global Space) or b) to the Object Center (Local Space). When you rotate a Bone it needs it XYZ relative to the Armature Center pluss where the Tip is in Global Space. It needs this info for any other bone connected to that tip since it will be transposed (in Global space) by moving the keyed bone and, since IK Chains (and FK Transforms) use the Tip, the bone behind the keyed bone needs to know too.
That’s the way I think of it. If you want a definitive answer ask one of the Python gurus who write exporters who have to parse this to be read both sides, Ideasman and Bob_Holcome.
For the sake of my sanity, I am going to just accept this. Kind of like accepting that the surface of the sun is hot, without seeking the same kind of definitive proof I got from the stove top as a young boy.
My understanding is that quaternions are used to avoid the potential of Gimbal lock that can occur with Euler rotations. Beyond that I can’t even begin to explain how they work and I must admit that when it comes to directly editing the IPOs to tweak bone motions, I just try and test, try and test and see what results I get.
Since Blender uses Eulers for everything else, I can only assume that the complexity of armature calculations (as Fligh explained) makes quaternions a better option for bones.
http://blenderartists.org/forum/showthread.php?t=98182 Sorry for hijacking the thread - i just posted on the exact same thing. I’m new to animation with blender, and I’m a little confused why it uses quart rotations instead of Euler rotations for armatures… wouldn’t it be simpler to just use Euler rotations and work around gimble lock if it occurs? I can accept how quarternions help, but wouldn’t they’re so unintuitive… maybe i just need to do more animation, and i might learn how to use them better. Does anyone have a way that they use to work effectively with quaternions, it would help immensely.