Help needed on posing.


(kostyabkg) #1

Hello, I am using an old model from Dedalo-3D web-site. And I need to pose fingers several times. But unfortunately when I do this several times (bend/unbend) this is what happens:
Before
http://www.geocities.com/kostyabkg/1.jpg
After
http://www.geocities.com/kostyabkg/2.jpg

I understand why it happens, but trying to figure out how to prevent for that to happen. Of course I can adjust it every time back to their original position, but this is not an acceptable solution for me, and it takes lots of time as well.

One solution would be using DoF (Degree of Freedom), but unfortunately this works only with IK chain, and i don’t need that. Another solution would be probably to lock the rotation of the bone around itself, but how to do it?
Does anybody have any suggestions?

Thank you!
Kostya.


(Fligh) #2

but unfortunately this works only with IK chain, and i don’t need that.

Well, an IK-Chain is always going to be the easiest way of posing fingers.

If you are not using an IK-Chain on that twisted finger then you’ll have to post the .blend and (IMPORTANT) an explanation of how you pose it or we’ll never be able to help.

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(kostyabkg) #3

I am sorry for taking so long to write an answer: university, studies…

As I mentioned I have a human model from Dedalo-3D site. I rig it and skin it as it’s described in their short manual using their GUI. Then I rotate the model, bend any finger, rotate the model again, adjust the bending, until this finger looks naturaly bent.

Then I unbend finger and this is when it starts looking that twisted. The reason is because, when I adjust finger I rotate the model and bend the finger multiple times, and this is when I twist the second bone counting from the tip and the tip around their joints. Yes, it’s possible to fix it with some additional work, but how do I prevent it from happening?

.BLEND file is:
http://www.geocities.com/kostyabkg/test2.zip , can be opened only with 2.40. If anybody knows how to open it with Blender 2.37a, let me know, please.


(Fligh) #4

That’s just an absolute mess. Nothing I did (clear transforms etc) can fix it. So, you are going to have to start over, which is not so bad because this armature is not good for hands the way it is setup now.

What you need to do is make the bones in each finger an IK-Chain that has a target bone. Goto edit mode and put your 3D cursor in front of the thumb on the right hand and add a Bone. Name it “Thumb_target.R”. Then goto pose mode and Shft-select the bone at the end of the thumb (the one with the nail on) and Ctrl-I >> Add IK Constraint >> Use Selected Bone for Target.

Now, when you select Thumb_target.R in Pose mode you will be able to close and open the thumb. Do the same for the four other fingers and you won’t have to mess with the finger bones again, just their targets.

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(kostyabkg) #5

Thank you, Fligh %!

Yes, it seems to be the best way to do it. I tried add an IK solver constraint to the tip bone - same mess. In addition to what you suggested I added a null bone to the tip bone of the chain by extruding it and only then an IK solver. Works well!

What do you mean, when you say:

this armature is not good for hands the way it is setup now.

Which way should I setup the armature, so that it would work better?


(Fligh) #6

I meant that the fingers don’t have IK constraints and targets, you have to put them in yourself. But you found that out yourself.

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(kostyabkg) #7

Fligh %, you were more right from the beginning: your approach without null bones works better, than the one with them.

However, there is a little question I have about DoF: how do I control the direction of those limit circles in the space? As far as I understand their direction is defined by XYZ axes, that are are drawn on the tip of the bone, if you toggle them on, of course.

But how do I change those axes, so that they would be aligned exactly the way I want them to be aligned? Say I want red circle (X) to be aligned along the chain of the bones and blue circle (Z) - to lay exactly in the plane where the chain of bones is laying. In this way it is so much easier to set up the limits.


(Fligh) #8

This is where the English language becomes useless.

It makes no difference which view you add a chain, these are the default Axii-Limits drawn in full. The way that I read your question that is exactly what you want. So you will have to draw what you mean.

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http://img.photobucket.com/albums/v625/fligh/BoneAxis.jpg


(kostyabkg) #9

I am sorry, but it seems like I wasn’t clear enough. Take a look at this picture:

http://www.geocities.com/kostyabkg/3.jpg

This is the view from above the palm, but note how the red circle is not perpendicular to me, and accordingly blue circle doesn’t lay in the plane where the whole chain of bones is laying. Therefore, because human fingers can bend only in one plane I would simply need to disable 2 DoF and leave just one, which I would be able to adjust this remaining 1 DoF according to my needs (0 to 90 degrees, for instance).

But because those circles aren’t positioned exactly in the plane where the actual finger bends/doesn’t bend, I need to draw something like this:
http://www.geocities.com/kostyabkg/4.jpg

thus creating an area to limit, and finger limited by an area behaves much wilder rather than if it would be limited just by 1 DoF and the rest would be simply locked (and this is what I would like to have)

I hope this will make things a little more clear.

I tried rotating the bone around its’ axis in Pose mode and edit mode, it doesn’t seem to help. Therefore I am curious how Blender computes XYZ arrows (axes) at the bone tip? Because as far as I understand this is exactly what I want to change.

Thank you for you patience, Fligh %!


(Fligh) #10

In edit mode use Ctrl-N to recalculate Roll Angle. You can see it in edit mode in the Transform Properties (N) tab.

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