Loc Y values are switched in ipo editor. Why?

Hello. I have the following problem when trying to animate a human armature:

  • at frame 1 I have the body standing up and I keyframe the torso location
  • at frame 10 I move the body down and keyframe the new torso location

When I go to IPO editor I see the changes made in Loc Y. In frame 1 I should have a higher value of Y than the value of Y in frame 10 since the body is moving from an Up position to a lower one. But the curve is reversed: in frame 1 is at a lower point and goes up to frame 10.

Why is this happening and how can I fix it?

If I animate a simple object - a ball/box going up-down, the ipo curve is as it should be: Up when the ball is up and Down when the ball is down.

The Z axis is for vertical movement… not Y.

Yes, I know. That’s another thing that confused me since I constrained the movement in Z axis when doing my up and down movement but no Loc Z curve appeared in IPO editor, just that reversed one for Y Loc.

your bone is upside down

you may be able to fix it by going into edit more and changing the bone roll 180 degrees
but it will depend on how the rig is set up

wanna post a blend?

Thank you waylow, I believe that was the problem so I’ll try to fix it as you explained. I’ve attached the blend file anyway.


LocYproblem.blend (359 KB)

bone roll won’t fix the “biped” rig
because of the axis it’s on - if you roll the bone the tip (local y) is still pointing down

the bone tip points down towards the ground so the legs follow properly when it rotates back and forward and side to side

you would need to add a new bone that points horizontal (with the z axis facing up if you want it to relate to the world coordinates)
then parent the hips to this

but I wouldn’t worry about fixing this rig - as long as you know why positive Y moves it down you should be right

(take a look at Mancandy to see a more complicated spine set up)


LocYfixed.blend (353 KB)