Biped and multiple objects

Dim · Dec 2010

Hey guys,

I'm using biped in Max to animate a character, and in the scene, he picks up two different objects at different times, with the same hand. The method I'm using to pick up the objects is to use a planted key on the hand, IK binding it to the object. This works great for the first one, but as soon as I pick up the second object, it overwrites the object it's being bound to for all previous keys.

I've searched around and couldn't find anything substantial, but I can't possibly have been the only one to come across this issue, so there must be a way to do it. Any help?

edit: this is the best description of the issue I have, but without a good solution.
http://area.autodesk.com/forum/autodesk-3ds-max/animation/multiple-ik-objects-for-bipeds-hands-and-feet/

sprunghunt · Dec 2010

every time I have had to do this I've just done it by having two objects and by hiding the one attached to the hand until it gets picked up and vice versa

Dim · Dec 2010

Thanks sprunghunt, that was my fallback plan, but it would be a lot easier if Max would just let each key have a different object.

Mark Dygert · Dec 2010

Yea this is a part of biped that is kind of murky, but there is a easy fix. You can get around it by attaching the hand(s) to dummy objects then attachment constrain those dummy objects to the world then various things you want to pick up.

In that thread they had all the right pieces but haven't assembled them correctly.

Hands attach to dummies, dummies are attachment constrained to the world and various objects.

When you animate you'll move the dummies to the object and activate the attachment constraint so they follow it, then animate the hand IK from 0-1 so it snaps to and follows the dummies. At that point you're no longer animating the hands but the object.

This can get a little messy at times as animating the hand IK is dependent on the objects position to connect and disconnect at specific places, if you re-animate the object they attach too, its easy to fubar those positions and cause a bit of a headache, so it takes some getting used to.

You can do the same thing with the head look-at too. Have it look at a dummy that animates around the scene and is placed next to the objects you want to look at, instead of trying to use the objects themselves.

Dim · Dec 2010

Thanks Mark!

That's a really helpful description, and I wish these sorts of answers were a little easier to find. Having already done most of the animation, is your solution something I can do retroactively?

Thanks again

Mark Dygert · Dec 2010

I would have to look at the animation and see how it was animated to say yes or no. It is possible, I've done it, but its a testy system to work with from scratch and doesn't get any easier when you put it in place later.

I would do it in chunks in different .max files and assemble the final chunks of baked out, key per frame animation in a final scene for rendering.

1) You do the first grab. Save the scene as grab1.max
Save out (Biped menu > Save .bip file), call it grab1.bip set it to key per frame to bake in the IK.

2) Clear the animation (keyframing tools > clear animation)
Load grab1.bip into your biped, save the scene to grab2.max
Retarget your IK do your second grab.
Save out a grab2.bip file with only the new non key per frame section of grab2.max

Following the same process in #2 for each grab.

When you get all of the grabs done load the .bip files into motion mixer, mix them down and apply that to the biped for final rendering. If you need to make changes go back to the non key per frame grab1-2-3.max files do your changes and save it out, mix it down and call it good.

One more bit of advice that helps smooth out weird little IK problems and other misc problems, is to put your biped in figure mode select the biped pieces, hold alt and right click, choose set skin pose. This goes a long way in fixing a lot of little crazy problems that pop up with biped, I can get into specifics if you want but if not its probably a good idea to build into your routine before animating.

Dim · Dec 2010

Thanks again Mark. I ended up splitting it into two scene files, it seems to be the only thing that worked. The dummy object thing didn't work very well especially because the character alternates between a two handed object, and a one handed one.

I appreciate the help

Mark Dygert · Dec 2010

Ahh two handed, I think that would create a bit of a looping issue, if both IK dummy objects target the same thing. In cases like that, you position attachment constrain another dummy to the surface of the pickup object where the 2nd hand will make contact and target that.

It can get pretty messy especially if you're adding these systems in after its been animated, I think you did the right thing by breaking it up. Technically that is how biped was designed to work and is probably the most stable. It sucks that is can preform like every other rig out there but has some doing it.

Glad its working one way or another!

Dim · Dec 2010

Here's the actual animation, using the cutting video together method. You should be able to see the issue there. This is also the first time I've animated a biped, so some feedback would be lovely, though this is definitely the wrong forum

http://vimeo.com/17540196

Biped and multiple objects

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