Rotation Z Channel Loop Creating Odd Motion Blur

I need help with something I haven’t seen before. I am tracking a camera that spins 3 times in 360 degrees. When I track and stabilize, any object that I add motion blur to will have a glitch once every rotation. I checked my animation channel and I can see that it coincides with a loop. I have tried dragging those keyframes down to line up in a contiguous fashion. That doesn’t seem to work. Any workarounds for this?

Translating the keys on Y so the curve is smooth should work, with the curve ending at negative 360 vs zero. You should be able to grab the second segment and translate it -180 on the Y and grab the third segment and translate it -360 on the Y to get a single smooth curve.

But you say that doesn’t work. What happens?


I feel like I’ve gotten this from a matchmover once, whoever was smarter than me and was helping me fix it called it a gimbal lock issue. Translating the keyframes fixed it up.

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Is this an axis rotation or camera?

So when I translate the keyframes in Y, the layer will flipflop to the opposite side. Keyframes look right, but the image mirrors over to the other side of the screen. I feel like I’m doing something really dumb here, but can’t understand what exactly.
test guy GIF

axis only

perhaps you can add an axis above with several constant keyframes that counters the rotation at the cycle points, or counters the flip if you translate the rotation keyframes

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I tried a counter axis, which corrects the position, but still shows weird motion blur on those frames.

Found a fix. When I copy the rotation to a new axis, translate the keyframes in Y, then add several keyframes to the parent axis to counter the motion shift, I get weird motion blur. However, if I reset the parented counter motion back to nothing, then the motion shift goes away. Weird, right?

Trying to reproduce just to make sure I’m not crazy.

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OK. I get it now. There was negative scale introduced in the original tracking. Not sure how I missed it, but there it is. So, negating multiple negatives makes for weird animation. Translating keyframes in Y was the right answer – I just need to make sure no other counter motion is being introduced. Thanks for all the help!