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Prevent skewing with bone rotation

Posted: Sat Aug 05, 2017 2:27 pm
by isby
Hi guys,

I've been at this for a while. I have a character rig that I've hooked onto mocap and all is well: I have a hip, a chest, two elbows and two fists tracked and I'm getting an interesting result as I track target bones to the mocap tracking.
However, there is one point that' busting my b****... Whenever a shape gets rotated, it also gets skewered. It's very time consuming to fix it manually, almost completely removing the benefits of the mocap.
So let me illustrate the problem.
Image
This is the 0 position.

Once I rotate it, the face get elongated.
Image

Is there a way to keep the original ratios?

Re: Prevent skewing with bone rotation

Posted: Sat Aug 05, 2017 7:24 pm
by synthsin75
It looks like you have a flattened targeted pin bone in the first image: https://drive.google.com/open?id=0B_Wv8 ... 0s0X1VLOGs

That would seem to indicate that you have the bone layer or one of it's parent layers rotated on the x-axis. That would cause the skewing when rotated.

Re: Prevent skewing with bone rotation

Posted: Sat Aug 05, 2017 8:57 pm
by isby
Hm, thank you. How would I check that? u

Re: Prevent skewing with bone rotation

Posted: Sat Aug 05, 2017 9:18 pm
by synthsin75
With the Rotate Layer XY tool selected, select through the layers and make sure the X rotation is zero.

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:25 am
by isby
Unfortunately, no. I've tried all the layers and they're all set at 0. I thought for a moment this was happening because I was using points but I insertedan image andgot the same result. It's the 2d rotation created by bones that messes it up

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:33 am
by synthsin75
isby wrote:Unfortunately, no. I've tried all the layers and they're all set at 0. I thought for a moment this was happening because I was using points but I insertedan image andgot the same result. It's the 2d rotation created by bones that messes it up
That doesn't explain why your pin bone is squashed. Maybe your camera is tilted.

Might be easier to diagnose if I could see the file.

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:42 am
by isby
Squashed as in just a circle? It's because when creating the tracking bones, I don't drag the bone out, I just click on the canvas, and get an orb. I was just checking it in Orbit view and it seems to be a 3d orb

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:45 am
by isby

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:50 am
by isby
Aaaah, I get what you're asking me now. I've gotten so used to it that I forgot it was squashed in that direction. It's sqashed because I've squashed the entire layer vertically when doing video tracking. Let me see if fixing that has any effect.

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:52 am
by isby
No, it doesn't fix my original problem, the character just get elongated.

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 6:58 am
by isby
OK; your comment made me start watching the bones rather than the points.
So I think my proper question here is why does the head bone on image 2 get stretched compared to the original position, i.e. can I prevent it from doing that when in rotation?

Re: Prevent skewing with bone rotation

Posted: Sun Aug 06, 2017 7:29 am
by synthsin75
That squashed layer is your problem.

As a general rule, I never do layer transforms while designing characters. Only while animating them. You can end up with problems like you're having, trouble matching stroke widths, etc..

Your first problem sounds like your mocap reference doesn't fit your character's desired proportions.