I have a problem with the arms of the animation between the frames with my run cycle:
It does the same thing between frames 27 and 30. What is happening? What can I do to fix this? What can I do to prevent this from happening again? Please answer these 3 questions.
It’s hard to tell without seeing the graph editor or the actual movement. My first guess is that you are using quaternions and the W on one keyframe negative and then switches to positive or maybe the other way around.
Another guess, is you are using Euler XYZ and you are experiencing the effect of Gimbal Lock. This is the BANE of animators. Yes even in Maya. You can see the Gimbal by going into pose mode(Ctrl+Tab toggles) then changing Transform Orientation to Gimbal(press Comma->Gimbal). Then select the bone. Gimbal lock is caused by 2 axis getting close and even matching up together.(Full Gimbal Lock) The Euler order of operations effects the Gimbal. Best way to explain it is First axis is child of second axis and both first and second axis is child of the third axis. So in XYZ. X can rotate without problem. Y rotation effects X rotation and the closer Y gets to 90, -90, 270, or -270 degrees the closer you get to full Gimbal lock. Z rotation effect both x and y. Full Gimbal lock sound worse than it is. This just mean that both the first and third axis now cause the same rotation because they are aligned. In other transform orientations(Global, Local, normal, etc.) This just mean that when you do a rotation Blender will rotate multiple axis to get to the rotation point set. This doesn’t always create a smooth flow between the 2 position. This usually means having to do the rotation in different way or adding additional keyframes in-between to correct the rotation flow.
*Edit
Here is a video that helps explain it. He is using Maya, but the video still Applies: https://www.youtube.com/watch?v=XCh-yEkHPMo
I watched the video and according what he said, I could easily fix this using the graph editor. The question is, as you might of have expected, how do I what he did in it in Blender?
As far as I know there isn’t a simple fix in blender. The way I handle it is to add corrective keyframes to fix it. This is why quaternions is so common in character rigs.
