Two hands hold the same object

[contrast]

I know how to use point and aim constraints to cause a hand to pick up an object, but does anyone have experience with rigging a character swinging an ax where they used both hands on the ax? Any suggestions? I am racking my brain trying to figure out a solution. Thanks in advance.

[mtmckinley]

I would imagine you'd have two points(locators, perhaps) on the axe that the IK handle of the arms constrain to.

[JTMajor]

Contrast, your suggestion works for custom rigs but I can't seem to get it to work for a HumanIK rig. I can get one hand to hold an object and the object follows along as expected.

But I cannot for the life of me figure out how to get the other hand to automatically stay attached to the object or follow it. :mad:

I've tried parent, point, orientation, etc., constraints using locators, the IK effector itself (wrist) and a few other things. It seems the HumanIK programming keeps a firm hold on the effectors and won't let anything other than the software drive them.

My HumanIK rig is properly setup and its definition locked. Using Maya 2013.

Does anyone know a way to make this work?

Thanks in advance!

[daverave]

Try grouping the thing that you want to hold then do a point constrain to that group..............dave

[JTMajor]

Thanks, do you mean point constrain the wrist's effector to the object to be held?

[daverave]

Yes I think that will work..........dave

[JTMajor]

Thanks for the input, Dave, but that did not do the trick.

Man, this is frustrating. I am trying to avoid keyframing the second hand for the huge scene I am setting up.

I don't know why this isn't a built-in feature of Maya.

Is there a setting in the HIK panel that will allow Maya to let HIK release control of the effector? I've looked but can't find the magic button anywhere.....

[daverave]

How have you got the first hand to hold the object................dave

[JTMajor]

Oh yes, no problem there. That part works fine. It's trying to get the other hand to follow the first hand and object that's stumping me. I did group the object before trying it.

I also tried parenting the object to the second hand's hand bone then parenting the object to the first hand but that didn't work either.

It seems I am going to have to resort to keyframing the second hand.

Thanks for your help, seems there is a 10 hour delay between us as I am in Colorado.

[JTMajor]

I can send you the scene if you want to give it a go. It would be later today before I could, however.

[daverave]

I can send you the scene if you want to give it a go. It would be later today before I could, however.

Im using maya 2009 and cannot open some newer maya files but you could give it a try:)...........dave

[JTMajor]

I do appreciate it but know 2013 files are not compatible with 2009.

[daverave]

When I said group you can group another group to add more constrains to a object, have a look at some suspension tutorial just replace your gun for the wheel...........dave

[JTMajor]

Thanks Dave, I get the part about adding groups for constraints. I use that method quite often.

The real problem seems to be the HIK software itself. I don't know what it takes to get HIK to release its control over the left wrist effector. It doesn't seem to want to let anything else drive it, such as a constraint.

[daverave]

Try point constrain at the end of the ik handle with maintain offset selected, if that does not work could you post a screen grab.................dave

[KyleButler]

I'm doing something similar and was having a hard time.
After a lot of tweaking and some forum posts, I came to this method, which won't work 100% of the times but should give you a decent result.
- Download Zv parent master.
-Select the axe, then one of the hands, let's the say the right hand, and use the Zv constraint;
-Create an ik handle from the shoulder to the wrist of the other arm(left).
-In the attribute editor, set the ik solver to hiksolver, otherwise your elbow will probably be upside down.
-Parent constrain the ik handle to the axe.
-Orient constrain the left hand to the axe.

It will take some tweaking, but it is a good starting point.

[JTMajor]

Beautiful idea, I will give it a go. Thanks!

[JTMajor]

Thanks again for the input and sorry it took me so long to reply.

I tried what you suggested but did not have success. Maybe I need clarification on your directions. When you said to "Orient constrain the left hand to the axe" did you mean constrain the left hand skeleton to the axe? That's what I tried. I guess that's the only way to do it since you can't constrain the HIK effectors.

The left arm did not follow the axe (golf club in this case). The only result was that the skin of the left hand did change orientation, but the hand skeleton did not.

I think I'm screwed on this one!

[JTMajor]

I did just have some success. I changed the IK solver for the IK handle to ikSCsolver and the hand did follow along. However, everything downstream of the hand (all the finger bones) stay put while the hand, wrist and upper arm follow along.

I may try to add IK handles between the hand and each of the 5 fingers and parent them to the "axe" as well to see if that will allow them to follow along as well.