Cineversity

Hi

I was in the middle of making an align to spline for a pivot object and then needed to stretch the walk or run to match the timing.  I noticed as I did this the legs flip out, but only on baked or compound clips.  I have no choice to compound or bake the clip as when I used loops I cant cut the clip up, here is my worlk flow.

1: Bring in a walk on spot animation
2: make a motion clip
3: loop it 5 times
4: Need to do cuts later on so must either bake it, or compound the clip so no loops are needed
5: I stretch out the baked clip and the limbs go crazy

Now while I can just loop the single clip and get the timing right then bake it, and then do the slicing I wonder if this is a bug.

Question is, can you produce this, is it a bug, and is there a better workflow.

Thanks, Dan

Post #10 has the solution.

Hi Dan,

This is not a problem of the Motion System.

In the given animation data you will find several areas where the rotation does a flip. See screen capture. This jump is normally not visible, but it might be with motion blur enabled. In short, it does it between the frames and so it seems normally invisible. If you stretch you animation, then it is no longer a jump from one to the next frame, it becomes then a transition or more precisely a standard interpolation over time.

Note that sometimes this is used (AFAIK) to avoid an Euler Flip. So, to just fix it (the Euler Problem), it has perhaps introduce a new problem.)

(The icon I used to show (screen capture) only one track is called “Show All Tracks”)

To move a group of keyframes in the F-Curve Timeline up an down, select the wanted keys, and in teh attribute manager use the “x-360” for example to subtract 360º to all selected.

I have captured a little clip (one minute) and here is as well the file back: (It is not backed again.)
https://www.amazon.com/clouddrive/share/N6m8iZqPXzIxCBC7XdtHfOdIa7UG1yEEu9teYMjSBro

All the best

Hi

Thanks for replying so fast, and finding the issues. 

Correct me if im wrong, are you saying that these bad keys where already there on the original animation but you wouldnt notice them when played back at normal speed, but making the clip slow allowed them to be seen, and that this has nothing to do with the motion system as in its not causing this when baking down clips?

When I take a snap shot of the original un-baked clip I see a smooth curve, when I look at the screen shot after its baked in the loops its got the issues that you highlited how to fix.  Does this not show that it is in fact the motion systems Baking that is introducing the problem?

https://i.imgur.com/GMKxA6N.png

PS: As in the image below you can see its these keys framed in red that need to be moved up, they didnt need to be moved, but the baking did rotate these 180 degrees.

https://i.imgur.com/be0aPnm.png

Thanks, Dan

Dan,

I have tried to get my “fix” (all keyframes in question X-360, or the other keyframes X+360, which will be the way to get to your source files) as normal keyframes and turn them again into a Motion Clip. I do not get the problem then. Edit: I will explore this more.

My best wishes

In the file I gave you, the clip named running is the original, a single run loop.  Looking at the keys for the legs they are fine.

Add a few loops to it and either bake the clip or use (convert motion clip to motion source), and the resulting clip has the legs flipping 180 degrees every 10 frames.  I will also give you the original animation file before it was even converted to a motion clip, however I can see that the issue is only there once the baking or convert to motion clip source is done.  i found earlier when I compounded, baked, or converted to new motion source the whole animation from multiple layers, the animation is a mess, arms and legs flipping.

PS: looking at the original fbx clip before converting to motion clip the legs are fine just as they are once converted to motion clip.  It is for sure the baked, or converted to new motion source that rotates these -180 degrees which makes these clips of no use for time stretching.

Thanks.

Thanks, Dan, for the FBX file.

Here is a screen capture of opening the FBX and turn it into a Motion Clip.
https://www.amazon.com/clouddrive/share/qkmzihVSMsZpYydz3u89IeVF43AFwV1VgMCHtfetq3M

(The only change that I have made to the FBX is to add your name to it, otherwise I would not know after a day what that files was, I get hundreds of files each moth. Naming is crucial.)

I can’t reproduce the problem. All looks fine here. I assume your are on the latest build of R19, right?
…

All the best

Thanks but you have confirmed what I have already found and mentioned.  The motion clip has not got the error until you apply a few loops and convert motion clip to motion source by right clicking on it, or bake it from the Motion System menu.

The resulting new clip has the error.

Dan

Watch this video.  Your see how baking the clips always produces the issue, and sometimes the Convert To Motion Source does have the same issue.

https://youtu.be/28xahiiVo3s

Thanks for the clip, Dan.

Have you tried to switch from Automatic to HPB?

Which made me explore if the Spline-interpolation with zero length handles were the problem. They didn’t cause it.

The next exploration was, what would happen if I select the keys that receive the problems during baking, and use the x-360 for the value. Now they sit in the lower part of the F-Curve. Any kind of baking doesn’t result anymore in problems. My conclusion, the baking obviously limits the value to 180º. However, a test with a 720º rotation didn’t got “staircased” to a “-180º to 180º ” range. No idea what it caused.

Since checking each hierarchy file for a problem, stretching the clip to a longer time, loop it, bake it and reduce time instead of expanding it worked here.

I can’t see any problems with the loop, the animation data seems to work as loop.

All the best

Thank you for investigating this, glad with your extended knowledge you could see it on a deeper level, and for now provided a workaround.

Thanks, Dan

Dan, have you tried the HPB setting?

The Motion System: Attribute Manager> Tag> Rotation Settings: “Auto/HPB/Quarternions”—Auto settings is after all my explorations the one that cause it.

The Quarternions try to get the shortest way (simplified said) and that might cause the flip. Your workflow of stretching and baking was the first to my knowledge that showed the problem, or even produced a problem.

So, if that problem shows up, choose the HPB.

The manual states Quarternions shouldn’t be used if the distance of two key frames is greater than 180º. Which is NOT the case here! So, makes me wonder what happens, and it confirms your question. All information I was able to gather indicate, that the problem you describe above is not intended.

I have created a file with three versions of your source file. Auto / HPB and Quarternions. Based on the procedure you want to use. The Loop (BTW) is not causing it.

Screen capture and file:
https://www.amazon.com/clouddrive/share/hCCHfxjupd5vTG44M0ijA7wMzYEMEnV80eJLNMRUg8p

I hope that helps to get your project in the way you like it.

All the best

P.S.: The problem is now reported.