Would anyone mind helping me to get my joints working properly?

I’ve been at this literally all weekend. This is my first ever rig, and I feel like I’ve made a lot of progress, but the joints are giving me a major headache.

If I get my knees pointing forward properly, the mesh gets twisted where the legs meet the torso. If I fix the twisting by adjusting the pole angle, the knees point to the side when they bend. Same issues with the arms.

Any chance someone more skilled than me could take a look at my blend file and see what the deal is? .blend is attached (v2.71) Joints are intended to be human-like, despite it being some kind of frog-like character.

frog2.blend (649 KB)

Several things need attending to:

  • First, you still have X-axis mirror turned on. With any part of the armature selected, go back into Edit Mode and look in the Tools roll-out pane on the right of the 3D View. Find “Armature Options” and you’ll see it. In fact, it’s the only thing showing there. Uncheck it.
  • Second, while you’re still in Edit Mode, go to Armature Properties and in the Display section, turn on Axis. Take a look at your bones. Select any single bone to see which way the axis is pointing. In the legs (I didn’t take a look at the arms, but I’m sure the problem exists there, too) I found the Z-axis pointing in various directions. It doesn’t really matter if they point toward the front of back, but they should be consistent. Same with all the bones for the feet, either up or down, but consistently in the same direction. Take a look at this Blender Cookie tutorial; if memory serves, Kent covers this at least a bit.
  • Thirdly, after getting your z-axises (axi?) sorted out, click on your shin bones (and, in the arms, the forearm bones) and look at the pole angle and adjust it accordingly.
  • Fourthly, when you’re rigging a character in Blender, any joint you want to bend in a certain direction should have the bones set up so they’re already slightly bend in the direction you want then to go. I say slightly because it doesn’t take much, just enough to tell the IK solver your intentions.

For a much better understanding of rigging characters, I encourage you to get Nathan Vegdahl’s Humane Rigging. It’s not expensive and he’s not just an wizard with building rigs, he’s an amazing teacher, too.

Hope this helps.


PS: Don’t be discouraged that you’ve only got this far in one weekend. It took me almost a month to build my first rig from scratch. You’re actually doing really, really well.

Well RonTarrant explained while I was taking a look that you had a prob with bone roll (Ctrl R to correct) I also touched up a few other things so you can check against this file while working on yours to see how things can be set up in Ik chains and with copy rotation constraints so as to have a minimum of bones to work with. Here the IK targets can be rotated to pose the hands and feet and moved to pose the arms and legs.
Good Luck!


frog_IK.blend (1.12 MB)

Thanks so much guys. My frog is coming along much better now. Still not perfect but a huge improvement.