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FK/IK Switch causes an unwanted rotation to feet

PostPosted: Wed May 22, 2019 4:41 pm
by olivier.royo
When I switch all to Ik and move up the root bone the foot just rotate 180 degrees. what is ma problem? blender version is 2.79b I m on a mac, makeHmuan exchange version 0.3
the screenshot is front view , human is facing

Re: FK/IK Switch causes an unwanted rotation to feet

PostPosted: Fri May 24, 2019 1:44 pm
by MargaretToigo
It does that when you move the root bone up in IK. But when you move the root bone down or back, the human will squat or sit.

Screen Shot 2019-05-24 at 9.30.24 AM.png
Squat


Screen Shot 2019-05-24 at 9.30.44 AM.png
Sit



Now, if you move the root bone up only a little, the human will sort of stand on their toes...

Screen Shot 2019-05-24 at 9.31.13 AM.png
Tiptoes


But if you move the root bone up too far on the Z axis, you get distortion...

Screen Shot 2019-05-24 at 9.31.25 AM.png
Distortion


This is the nature of reverse foot rigs, which are good for some applications and not so good for others.

I have found that IK is better for posing humans for still shots, but that FK is better for animation, especially mocap. Of course, it all comes down to personal preference, so your mileage may vary, as they say.

The cool thing about the switchable rig is that you can choose which one works best for whatever you're doing at any given moment.

Re: FK/IK Switch causes an unwanted rotation to feet

PostPosted: Fri May 24, 2019 5:17 pm
by Aranuvir
You can solve your issue, at least partially, by rotating the foot.rev and toe.rev bones. But the solution has its limits, as Margaret explained very well.