View Full Version : Make Joint Chain Woes

11-24-2008, 11:28 AM
Hello all,

Well I'm having a love/hate relationship with the new joint system in v9.5. I think it's wonderful and when I work with it - 13x - and it does that same thing each time = Arrrrrgh. I'm probably missing something...

OK, watched the William Vaughn vids on the subject - Thank you so much as always (He really is a great dude). Do a dry run through the excercises with only a null representing the character and it's a thing of true beauty.

-Then I try it on my character, the joint chain is parented to the Root bone of the rig (PelvisBase), I move the leg chain joints into position (I've parented the chain before and after moving the joints with the same result). See screenshot 1.
-Make the top joint 'Unaffected by IK of desc...'
-Select the Ankle & Knee Joints only.
-Apply 'Make joint Chain'.
-The Goal ends up right on the ankle spot - beauty!
-Here's the Arrgh - the Knee and Ankle joints shift positively on the X Axis. See screenshot 2.
-The foot rig suffers.

I'm getting my rigging chops going and it's an uphill battle.

This happens each time, I've been at it all weekend and my frustration is really mounting. I wonder if it has to do with me moving the joints prior to the tool application? The way this character is, I could probably live with it, but it throws off my reverse foot rig (ala William Vaughn as well).

If anyone has a pearl or thought, I'd appreciate it.

11-24-2008, 12:04 PM
I am having a similar problem - I think - with joints and IK. Funny thing is when I did the reverse foot tutorial, the first time. It worked. Every other time I tried it in another scene the goal keeps popping out at extreme poses causing the rig to stretch or collapse. What particular issues are you having with the foot rig?

I am wondering if they are related. Not sure what I am doing wrong. But I did not get a response in the Beta forum. If you upload your scene I'd like to take a look. Here's three scenes showing the good one I made and two others that failed. I have no idea what I did wrong.

If nothing else maybe you can take a look and see if it seems related to what you see happening.

11-25-2008, 05:28 AM
Thanks for the reply Surrealist. I looked at your scenes and they look like they are all rigged the same. It's probably a switch or something on the buggered ones. I got my game on as far as modeling, but IMHO, Rigging is what I am focusing on right now 'cause it's still a little 'dark art' to me ^_^.

I have been successful a few times doing Proton's tut. I noticed that if the rig's done in one axis it's fine, but when I moved joints off axis, the joints move off base the Make Joint Chain is used. I guess the new tools have to be tweaked a little on Newtek's end. (I just got an idea - back in a few...)
I (may) have to go back to Jonny Gordon's book for now. I really want to get this guy done so I can get my reel going. (I blew last weekend and last night trying 13 different ways of getting it right - self-teaching/learning is hard and frustrating work) Good luck man.

11-25-2008, 05:56 AM
Found a work around... This is kinda the tail wagging the dog, but it worked.

- I remodeled the legs so that the new joint chain would run in a straight line on the Y axis (I'm using weight maps anyways for Bone Influence).
- I added a new Null Object, parented by the PelvisBase Bone.
- Moved the Null directly over the leg so the new joint chain will be on the Y axis.
- Ran my Joint chain down ala Proton vids.
- Selected the 'Knee' and 'Ankle' joints, ran the Make Joint Chain tool.
- ...wait for it...
- Prima! It worked.
- Save Scene Increment (do not pass Go, do not collect $200).
- Let's try the rest at lunch...

Dale Carnegie training indicated that I'm an extrovert ^_^.

11-25-2008, 06:10 AM
Just a little PS and a screenshot.

Note: the Joints DID MOVE a little, but I'm happy with the result and it's workable ")

11-25-2008, 07:12 AM
Well that is interesting. Thanks for taking a look at the scenes. Can you upload a scene minus character? I'd like to have a look see.

11-25-2008, 09:20 AM
Here ya go. Good Luck on figuring yours out. I figure if you keep the chain in 1 plane, the tool will work w/o too much scattering of the joints. If this works, I plan to redo the arms as well...

FYI: I posted same on Spinquad and Splinegod said I (we) aren't the only ones in this boat...

11-26-2008, 03:21 AM
OK, I'll take a look. But also, have you thought about just building the Joint chain by hand and see if you get the same result? In the manual it says something about it working only on one plane so I think it is the correct way to go.

It does seem as if joints are a little buggy with a few things that are not quite working. It may be what we are up against. I think that they are a very powerful new way to rig and animate in LW and it works completely differently than Z axis bones but it does seem as if some things are not quite right yet. I'll take a look at your stuff.

But as a side note as a result of this IK problem and a some things I read in the manual about targeting and use of the new constraints as well as my own experiments I am actually moving away from IK entirely. I am thinking that IK is really a limited solution that joints give a much better answer to in many ways if you are willing to think out of the box with your rig it is actually much more flexible and intuitive to use than IK if you set it up right. Currently I am experimenting with a rig using this concept.

Here is that section in the manual regarding constraints:

A “Same as Item” controller has been added to the Motion Panel controller options popup list for Controllers and Limits. The channels controlled by this option will have the same values as the corresponding channels of the set item. The stiffness value can be used to interpolate. The one for position has the option to use the world coordinates of the position item (instead of local). The calculations currently assume that X, Y, and Z are controlled, so the result may not be optimal if not all three position channels are “Same as Item” controlled.
Pole Item
A new “pole item” has been added to the motion panel, to be used in combination with the new “Align to Pole” motion controller setting in the Controllers and Limits Tab.
It is similar to the target item, and typically used in combination with it. It sets the angle controlled by “Align to Pole” so that it points towards the pole. Typical usage is to set heading and pitch to a target, and bank to a pole. That way the item’s Z axis will point at the target, and the pole controls the banking around the resulting Z direction.
This can then for example be used as the base of an IK chain as a pole vector. Set the heading and pitch to target the goal of the chain, and the bank to align to a pole item.
You are already familiar with one way of defining orientation: specify heading/pitch/bank values. These three values are sufficient to define any orientation. Another way is to define a target which the item should point at (giving a heading and pitch), and a pole vector to fix the bank angle so that the item’s up vector is in the general direction of the pole.
Notice the complete lack of mention of IK in the previous paragraph. Target + pole can be used in any situation where you may want to set orientation based on direction towards other items.

11-26-2008, 05:43 AM
Hey Surrealist,

If you didn't know about the vids that Proton put together for joints (along with many others for previous rigging strategies), here's a link...


I added the latest ones from the NT forum. Although I believe these were put together in the OpenBeta and some functionality is on it's way and not here yet..well v95 at least.

Be sure to look at the 'Intro to Pole' vid.

BTW: When I try to make the reverse foot rig AND THEN parent the Ankle null to the Foot null, I crash LW every time. I'm not an expert by no means, so I have to take another step back and see what I'm doing wrong..

I guess I'm gonna just have to can the new technology and go back to the tries and true KISS method of the old era masters.

11-26-2008, 06:29 AM
And actually as I am looking at your problem again. It seems as if what is happening is that when the joints get oriented to the goal they shift. Is that correct? If so, I think you could correct it by turning off IK and snapping the joint in place again and creating a keyframe. Just a guess. Something I had happen with targeting and that was the solution for me.

As for the scene that one you uploaded looks OK, the joints seem to be all connected. So was that the good scene? Or is there something I missed?

11-26-2008, 06:32 AM
BTW yes. I was very aware of those videos. That is what got me started in this and then looking at the manual and doing a bunch of tests on rigging and then on joints. Sequence of actions my be a problem. That is something I thought of.

Well, I guess this open beta material and unfortunately there does not seem to be any interest as I have not gotten any responses.

I think I will send my scenes in as a fog report.

PS: Re canning the new technology. I think the main thing is that it is a different way of rigging and it may be that an entire new approach - one that may even lead away from IK - is needed. Thing is these joints don't need to be constrained to a location like you have them in IK and that is part of the power of working with them.