IK Pole Target gone wack :P

hey, i was hoping someone could take a look at my .blend, i can’t figure out this pole target (on the left arm).
i dunno if it’s an issue of hierarchy, bad ik constraint settings, or just that i modeled the arm wrong.
im guessing arms can be a little tricky with getting the shoulder and elbow and wrist to all have their own movements and still cooperate :eek: haha.
thanks alot if you can help!

–> here is the file (1.24mb)

Several issues, and atm I can’t give you a full solution for this particular rig. Some advice though:

  • put the subsurf modifier below the armature modifier. For faster AND better deformation.
  • elbow.L is on a strange place, it’s on top of the arm. The actual elbow of the arm points to the back. Elbow.L should be placed there
  • the bones aren’t rotated properly in edit mode. Use ‘Z-Axis Up’ (Ctrl+N) and Bone Roll (Ctrl+R) to rotate the bones correctly
  • with correct placed and rotated bones the Pole Angle (found in the IK constraint) needs a different rotation
  • armTarget.L is parented to the hand bone. Better not to do that

thanks so much for the advice.
i followed the check-list as best i could:

1 and 2 were easy enough

as for 3 i did it to all the bones and it screwed up the leg bones a bit. should i still apply that to all the bones in the rig and then go back and roll each one til it gets to how it should look?
what does the bone roll do? i’ve never adjusted it before.

4, i did that until the arm looked right straight out to the side, but then when i bend it no angle seems to be the right angle. :confused: i’m sure i’m just missing something

5, what do i parent it to then? doesn’t it have to be the child of something? right now it’s parented to that bone on top of the hand called “wholeHand.L” which is just a control that i had the elbow and the arm target parented to.

here is the updated file (as far as i could get)

As for 3, the roll angles are still off seen attached screenshot, notice how the axis of the bicep and forearm don’t match? They should match. In edit mode, select those bones and use ctrl-n to adjust them. Also, in edit mode, your arm is bent forwards at the elbow, see the second screenshot… Try adjusting the elbow joint so it is to the back of the character. Giving a bit of pre-bend to an ik chain is always a good practice. With my arms outstretched, I can’t position my hands so they are behind my elbows, can you?

Then setting the pole angle of the ik constraint to 180 seems to fix it…

Randy

Attachments



hey thanks randy, things seem to be working better now.

how’s this look? – tallguy39.blend

Lookin better…Here’s a quick tip - in the 3d window, very right hand side of the header, there are icons for copy pose/paste pose/paste flipped pose. If you pose the right side, arms and legs, with the pose bones selected, use copy pose, then paste flipped pose. If the flipped pose isn’t correct, it’s a bone roll issue, your bones are out of sync as far as the roll goes from left to right.

Randy

ok wait, so true or false: the z-axis of each bone should correspond to the way it should bend. now that i’m typing it that doesn’t sound right at all. randy you said they should match…ok.
well anyway it seems like the main problem is that i need the arms to be pre-bent a little.
also i’m having a little trouble with the knees now. this bone roll thing is driving me nuts haha.
one more thing, what’s the best way of getting the pose position to match the rest position? switching back and forth makes the bones with ik constraints adjust a little bit.
i’ll try to post an updated .blend soon.

OK, I’m actually rigging a character right now… When I rig a character, I check that poses can be copied and pasted using the ‘copy pose’ and ‘paste flipped pose’ tools blender has. I didn’t do that once, and had to correct the bone roll for most bones to get it to work, lesson learned. I’ve attached a screen shot showing the character, and all the bones from the shoulders down to the fingers, the z-axis is pointing upwards. On the legs, the z-axis is pointing forward. The feet can’t be seen, but I think the z-axis is pointing upwards. In armature edit mode, blender has a menu option to reset these for you, look in the armature menu in the 3d window.

IIRC, your last posted .blend worked, but yea, the bones weren’t pre-bent. In my screenshot you might notice a slight pre-bend in the arms and legs. The issue of the bones changing position from edit mode to pose mode isn’t really much of a big deal, as long as they are not moving much.

But yea, post up a .blend and I’ll look at it…
Randy

Attachments


thanks for all your help randy (and nice character…do you have a blog/website?)
I’m pretty psyched because it seems to be finally looking good again.
I’ll try to fix the bone rolls like you said. and yea its gonna be some more tedious work cuz then i have to adjust the custom shapes :rolleyes:
but its getting fun again, i have mostly just the hands and face left now:
http://jasonrayner.com/tallguy44.blend

I looked at your .blend - the arms appear ok, but I’m wondering about the track to constraint on the armtarget bones. Normally I just create a small bone to be the target for the IK and use a custom shape for it. I did notice on the legs you set the pole target angle at 70 so the character stands a bit bow legged. You could simply set that angle to 90 and move the taget bones outward to make it bow legged. In the armature menu in pose mode, there is an option to apply current pose as rest pose. Or you could set the pole target to 90 and in edit mode, move the knee targets out so it stands bow legged. I like to keep everything square and at right angles as far as pole targets and stuff like that goes.

I did take a look at the feet somewhat…didn’t get too into it, but your foot controllers have their bone rolls screwed up. Just grab one foot controller and move the foot upwards and forwards, then copy the pose, and paste the flipped pose. The other foot moves upwards and backwards.

If I may ask, how did you build this rig? Did you build it using x-axis mirror or did you construct one side, copy it and mirror it to create the other side?

Anyhow, yea I think you got a good grip on what is going on, you just gotta get in there and do it. I can’t think of anyway better to learn than by doing…

Randy

i must have missed your reply somehow:

im pretty sure i built the majority of the rig with the x-axis mirror, but the legs i definitely copied and flipped. thanks for all your tips though, i’ll start working through those. so far i’ve just been dealing with what i got cause its doing what i want it to so far. but getting it done the proper way will probably keep things clean in the long run.

i’m not sure what you mean about the arm targets…i was using a track to constraint to keep the bone shapes (bracelet-looking things) perpendicular to the arms. its only for aesthetic purposes, doesn’t serve any practical role in the rig.

also the arms still aren’t quite right…i currently have the pole angles at 0° for the left arm and 180° for the right, and they act differently when bent even though they look the same in rest mode. i will have to post another .blend soon.