I'm trying to rig the wing of a bird (I'm following the piero training course of the CG Cookie) and a strange behaviour is happened when I added a new constraint to the bone called "CTRL_armPole". It seems that the whole wing is broken. I add two videos,the first one is a little piece of the tutorial that I'm following,and the second one is what happens to me :
1: little piece of the tutorial
how can I fix this situation ? thanks.
change the pole angle in the IK constraint to have it pointing toward the pole target, you have to eyeball it.
Quadripedal Rigging: Twisted limbs
The reason why the person in the tutorial didnt need to do it was probably because their bones had a different role angle (select bone in edit mode Ctrl R and rotate it) or the bones have a different rotation mode (select bone in pose mode, go to properties editor->bone->transform->rotation mode)
This is because pole angles aren't always created properly in blender. There is a setting in the IK constraint that allows setting this pole angle manually, specifically for cases such as this. You can find that here:
This effect is common when building IK chains. You can see that with even a very simple chain here:
Realign the chain with the pole angle, like this:
In your case, it looks like your pole angle will be 90 or -90 degrees. There are numerous ways to get the correct angle for this setting, but the easiest is during chain creation. I always make my IK chains coplanar and always on the cardinal axes (global X, Y, Z) from an orthographic view. This keeps every bone on the same plane with proper roll angles and the pole angle will always be some multiple of 90 degrees.
There are more technical ways to find the pole angle, for example this script, but these are more targeted at technical artists.
You can find more information on this answer.
