I have an armature and a set of empties that line up with each endpoint of a bone by their relative positions, but not by their literal locations or overall scale.

the setup

The empties are animated in the way I would like the armature bones to move.

how the empties are set up

How can I map the relative positions of these empties to the bones' rotations? I'm using Blender 2.79.

desired result

(I do NOT want to just match the literal locations of the empties to each other by scaling them down or scaling up the bones, as pictured below.)

what i DON'T want to do

UPDATE! Thank you to batFINGER for letting me know about the Track To object constraint. Now I can do this:


(Yes, I did start with the tutorial from Remington Graphics on using a Kinect for motion tracking. He did not mention in his video how to assign the Motion Tracking data to an armature that isn't what he set up in his free .blend file, which is what I set out to do here. While he uses Stretch To constraints, I use Track To and Copy Rotation.)


Rotation constraints.

enter image description here

Going off the image in question, contend this can be done with two copy rotation pose bone constraints.

Add a copy rotation constraint from base pose bone targeting base emtpy. Check the offset property. Do for corresponding bone - empty pairs down the chain.

  • $\begingroup$ That's helpful, but it's not what I'm looking for. I've updated the gifs in my original post to more clearly show what I need- I should have specified the empties I'm using are not parented to each other and do not individually rotate. (The context is that the empties are motion tracking data.) $\endgroup$
    – wavetro
    Mar 31 '19 at 20:32
  • $\begingroup$ Doesn't surprise me. Can still be done same way by adding empties that track to another, and copy their rotation as above. $\endgroup$
    – batFINGER
    Apr 1 '19 at 7:42
  • $\begingroup$ How do I add these empties that track to another so I can extract that rotation data for the bones? $\endgroup$
    – wavetro
    Apr 2 '19 at 11:05
  • $\begingroup$ Whoops **adding constraints to empties .. Try adding a tracking constraint to the existing empties. eg 1 track to 2, 2 to 3. If its a 2D hinge recommend a fixed track constraint and locking a chosen axis to pivot on. $\endgroup$
    – batFINGER
    Apr 2 '19 at 11:37
  • $\begingroup$ YES! That worked, thank you! Feel free to update or post a new answer and I will mark it as correct $\endgroup$
    – wavetro
    Apr 2 '19 at 21:15

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