I have this recurring issue where I will follow a rigging tutorial but when it gets to the IK part I find that my characters always seem to end up with knees that bend backwards. I’ve tried rotating the bone and then changing the pole position on the IK constraint to get things working properly, but now whenever I go into pose mode the knees are bent and there doesn’t seem to be any way to fix this. Any ideas?
Supply a link to your blend file so someone more knowledgable can review what you have done wrong ?
but now whenever I go into pose mode the knees are bent
Pole Angle is set in Pose mode under IK constraint. Are you setting the Pole Angle there?
Appreciate the replies
@Richard Marklew: Yeah, I probably should have thought to include the blend initially, but by the time I remembered this thread was gone awaiting mod approval. The blend file can be downloaded here: https://drive.google.com/file/d/0B99Q5VcmvSP6WXlqQS02VEJadmM/view?usp=sharing
@ridix: Yes, that’s where I’ve been going, but to fix the problem I seem to need to rotate the lower leg bone and then change the pole angle to compensate, but doing that introduces the knees bending issue.
Legs needs to be redone. Mainly all you have to do is delete the lower leg (Leg bone) and stretch the thigh to the head of the foot bone. Subdivide the thigh so you have two bones for the legs. Rename bones according of axis of course. Reset your IK’s after all this.
Your IK’s will be hard to animate/pose at the moment. The foot is not being controlled by the IK and will be hazardous down the line. Duplicate the foot bone and remove that newly bone’s parent and set it to root. This will be your new IK bone. Now have the foot bone copy rotations to the IK bone with constraints. The foot should now rotate when you rotate the IK at the same time. What you might have to do is make newly Knee bones. Delete knees and extrude a bone from between the thigh and leg bone. Remove the current parent just as before and parent the newly made knees to FootIK or root. Adjust the pole angle in the IK constraint. Of course always rename bones according to axis after making new bones.
Thank you for the detailed reply, though I’m having a difficult time following. If it wasn’t obvious already, I have very little rigging experience. I was constructing the rig just as the tutorial instructed, maybe I should use a different tutorial if it wasn’t right. Also, it was having me extrude bones rather than subdivide and reposition, is one option generally superior? As it stands I’ve deleted the legs below the knee as well as the IK and knee bones.
Is the bone setup I had right at least? Should I reconstruct that the same way? What do you mean by having the foot bone copy rotations with constraints? When you say duplicate the foot bone for a new IK bone. do I keep it in the same position or do I move it to make it easy to get to for posing? Also you’re suggesting I do knees differently, these are just bones extruded from between the bones of the thigh and leg, not separate from the body like the ones I have currently?
This is the tutorial I’m using by the way, not sure if it’s any good, but I’ve tried others in the past and I always give up when I inevitably run into problems like this
Oh sorry, I would recommend a foot IK tutorial from VscorpianC’s youtube tutorial [https://www.youtube.com/watch?v=CHdp7Os8l5Y]. I’ll send a few rigs you can look at. Basic leg, Basic IK, and VscorpianC’s foot rig. I still think you should go with VscorpianC’s foot roll tutorial so you have a better understanding on how it works. It is kind of long but it will help.
IKleg rigs.blend (482 KB)
Great, thanks. Going through all her rigging videos now, very comprehensive. If by the end I can up up with a rig that works as well as the setup in that blend file you posted it will all be worth the time spent. Tempting to just borrow that leg directly, but probably more informative if I learn how to build it myself.