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More joint limit observations/odditiies
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More joint limit observations/odditiies // Bugs
Post by Igor K Handel // Aug 3, 2008, 8:32am
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Igor K Handel
Total Posts: 411
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Theres something very odd going on in the joint limits tool. It's difficult to quite pin it down.
The gist of it is that if I expand my limits in say the x axis, firstly the bone won't always pop back to the position it started in. Secondly even resetting the changed limits still sometimes leaves the bone now at a weird angle, and it wont reset back.. even with a ctrl Z for undo. And thirdly the circular ring that represents the plane that is 90 degrees to all the limits (hard to describe lol) um its the circular handle used to rotate the direction of ALL the limits as a whole. Phew... after altering limits it often moves to an apparently unrelated angle to all of the other limits. Once it happens there appears no way either in the stack panel numbers or the visual drag handles, in 3D to get it sorted out. This behaviour is also present in the twist axis as well, and again the bone cannot be returned to it's initial position through undo, or changing the limits back to their start values.
It's like someone needs to tighten the bolt that holds the centre of this tools axis in place lol :confused: (looks for lock nut)
See my prev posts example vids for some visuals of what I am trying to get across.
Yours
IK |
Post by Electric Jim // Aug 7, 2008, 6:46am
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Electric Jim
Total Posts: 98
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I've definitely encountered the problem of not having the bone snap back in place after sweeping out rotation limits. I saw this frequently in tS7.51, but much less so (if at all) in tS7.6. It was precisely because of this that I got in the habit of using the numeric fields in the stack panel to set the rotation limits, rather than dragging the widget in the 3D window. (Much less intuitive, but at least the bone wouldn't end up being rotated from where I wanted it to be.) At least for me, when I saw the problem a CTRL-Z Undo (or two) would get the bone back in position.
One thing that sometimes seemed to have an impact is this: If you have already swept out a rotation span, then want to change that span afterward: When you click on the edge that you want to change, start out by dragging it slightly in the direction opposite to the one you want, then reverse direction and drag it in the desired direction. (So if you want to drag it clockwise, start out dragging it counter-clockwise for a bit, then switch and drag it clockwise.) I don't know why, but this sometimes seemed to have better luck at getting the bone to snap back, afterward.
Regarding the orientation of what I'll call the "little overall axial rotation ring thingy (loarrt)": I think an example of what you're talking about is shown in the accompanying pic of my character's wrist bones, with the way the "loarrt" is at an angle relative to the forearm bone...? I don't know of a way to control this, either. I get the impression that it orients itself based on the relative angles of the bones on either side of the joint. (Just to eliminate a point of potential complication in the future along these lines, I've been thinking that perhaps I'll add an unused set of mirrored thumb bones on the other side of the hand, keeping it symmetrical and -- presumably -- making the "loarrt" stay straight.)
I wish I could offer something more useful. :o |
Post by RichLevy // Aug 7, 2008, 8:18am
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RichLevy
Total Posts: 1140
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I haven't tested this in 7.6 but in 7.51 you needed to move the joint rotation widget (for the arc), either to the right first, than move your limit to the left (possibly the reverse of what I described). If you do it in the reverse, you would move the orientation of the arc swing.
Again I have not tested this behavior in TS7.6 yet so I do not know if this was resolved in the new release.
I'm not sure if that was of any use.
Rich |
Post by Jack Edwards // Aug 7, 2008, 8:54am
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Jack Edwards
Total Posts: 4062
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Yeah, it doesn't snap back until after the limit is set in the opposite direction as well. And default pose won't set it to a pose that's outside the joint limits. So you'll probably need to set up a new default pose after the joint limits are set.
One thing that can help is to select the joint with the shape skeleton tool, set it to object coordinate system, then rotate it so that the axis are lined up the way you need them for FK, before assigning the IK limits. |
Post by Igor K Handel // Aug 7, 2008, 10:03pm
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Igor K Handel
Total Posts: 411
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Thanks for the replys guys
Jim.... Your Loarrt made me laugh.. Not the easiest thingy to describe:D I really hope its possible to avoid your extra thumb scenario, not exactly ideal.
Rich.. Cheers for the counter rotate suggestion, which seems to have the favoured vote as Jim mentioned it too. I will try that see if it helps.
Jack.. Thanks for the suggestions. Yeh I tried your alignment idea a couple of days back as I did wonder if it had any bearing on the problem. Jury is out as the non centering problem still happens, but maybe not as often though. Just something odd and hard to pin down overall.. have yet to find any logic as to why it does it sometimes and not others.
Cheers
IK |
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