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pete
09-29-2002, 03:41 AM
Hi everybody!

I've been working with this Bones/IK setup for a character for a while now with the hope that I could completely remove myself from having to use CStudio. Daniel Lara's rigs were espesially helpfull and inspiring! (thanks man you rule) and Max 5's revamped Track View makes it that much easier to access the keys of your rig that it is a joy to animate...
Except...
The one thing that is stopping me from finishing the whole rig is..............(dramatic pause)............the wrist.
If anyone has a good solution for the twist problem with a characters wrist could you pleeeeeassseee post it here....
I desperatly want to kiss CStudio goodbye and I can smell the scent of victory in the air..

Thanks

- Pete -

goosh
09-29-2002, 03:50 AM
What's your problem with the wrist?

Goosh

pete
09-29-2002, 02:24 PM
well it goes like this.......(i hope I can explain this properly, I couldn't seem to add an image to this post)........

When the the hand twists it's area of influence goes almost right up to the elbow (because of the twisting of two bones in a real arm) but when you rotate the hand down or up or from side to side you only want it to affect the skin in the area of the wrist....
This is where the problem lies.......sag...

"Skin" modifier in max works by you saying - I want this bone to affect this area. So I really need it to work in a way that when the hand bone twists, there is a bone near the elbow that stays still and one near the wrist that inherits the twist of the hand but no more. But I'm sure there would have to be other ways as people would have come up with this problem before..

Thanks for the reply, I hope it's all a little more clear now.

KiboOst
09-29-2002, 03:08 PM
Don't really know this specific problem, but I think you could add some bones and link them right to achieve this, no ?

Kib

-dc-
09-29-2002, 03:22 PM
one way to defeat this is by creating Ulna and Radius Joints with IK handles for each. You'll need to create an extra joint between your arm root joint, the elbow and the end.
so instead of:
arm root>arm mid>arm end
try
arm root>arm mid>arm turn>arm end

Make ik from Arm root to arm turn, and parent that to whatever is going to be translating the hand.
Parent the Ulna and Radius Joints to your elbow joint.
Make a locator and snap it to the end of the ulna joints, and point constrain the ulna IK to it. Then parent the ulna IK and locator to whatever controls your wrist rotation.
Parent the radius IK to the same thing.

Now when you rotate the arm turn joint, your wrist should rotate, and your hand should follow, the radius should rotate around the ulna.

I use maya, so I'm not sure if that's helpful to you, but I'm assuming it's the same concept either way.
You can also use a lattice around that area with to help smooth out the deformations in the wrist.

regards,

Joe

derelict
09-29-2002, 03:53 PM
Hi,

If that is it, you can control the envolope properties groupings. There are many parameters in these grouping like squash, relativity and absolute and the radius thingy. Later you can manipulate the falloff for the weight (which is what you want). Safe another file from your existing mesh and try it. Set the area of effect as you please... Oh, the falloff is in the envelope.

Set the visibility on during manipulations (Slow and sinual falloff might be your cup of tea)

If you want more control you can asign a gizmo to add more control through asigning and locking vertices to it. It is at the Joint Angle which is a deformer.

Ps: You can set the colouring for easier area asignment.

PPS: Gods! i assuming you're using MAX? The above is MAX. :)

jschleifer
09-29-2002, 08:31 PM
The radius and ulna technique work very well for systems that can handle volume.. (i.e. if you've got a muscle system, it's awesome. :) )however, if your skinning solution doesn't deal with volume well, then you may want to try another technique..

What I like to do in Maya is create a multiple joint structure where I've got the following:

shoulder-->elbow-->wrist

This structure has ik on it and is what I use for animating. Below that is a structure which is used for skinning, it looks like this:

skin_shoulder-->up_shoulder-->mid_shoulder-->low_shoulder-->skin_elbow-->up_forearm-->mid_forearm-->low_forearm-->skin_wrist

Anyway, you then take the shoulder.rotateX (or the one that twists around the bone) attribute and spread it down along the up_shoulder.rx, mid_shoulder.rx, and low_shoulder.rx. Take the ry and rz attributes and connect them from shoulder to skin_shoulder.

Do the same with the wrist, taking it's rotation and spreading that back up the forearm.

hope that helps! :)

pete
10-01-2002, 02:58 AM
Thanks for all the help on this, I'm tring out some of those methods now..

Once I've finnished it I could try to attatch it's max file to this thread if anyones intersted but I've been having trouble adding images to posts..

nimajneb
10-01-2002, 04:42 PM
"Skin" modifier in max works by you saying - I want this bone to affect this area. So I really need it to work in a way that when the hand bone twists, there is a bone near the elbow that stays still and one near the wrist that inherits the twist of the hand but no more. But I'm sure there would have to be other ways as people would have come up with this problem before..


Have you worked through the Character Rigging Tutorials for MAX 5? Micheal Comet uses a series of wrist twist bones to deal with this issue I think, in that tutorial.

LFShade
10-02-2002, 05:00 AM
I'm not sure what setup is used in that tutorial, but I put a decent one together based on one of Lara's setups. Here's a link to the Max file.

wrist twist example (http://www.cgtalk.com/attachment.php?postid=89829)

pete
10-02-2002, 06:59 AM
Wow, thanks for the file, I've just checked your arm rig out and it seems pretty nice. The finger helpers look as though they'd be pretty handy too. I'll check it out in a bit more detail after work..

Oh and I'll also try to post up the versions that we come up with soon.

TheDevil[DK]
10-04-2002, 05:46 AM
http://www.cgtalk.com/showthread.php?s=&threadid=15142&highlight=twist

pete
10-04-2002, 08:53 AM
hi there devil,
Thanks for the post about the wrist problem we are having.
I have tried several different methods now but all of them seem to have inherant problems of there own.
We have alomost settled on this weird "look at" method but its a bit screwy. So did you eventually decide to sit on one method that you liked?

TheDevil[DK]
10-04-2002, 02:03 PM
I still use the 2-4 boned twist... but I'm a little bussy with some different projects, so I'm going to look at it again when I get some freetime...


Here... is some elbow stuff with bones (3dsmax5):
http://www.cgtalk.com/showthread.php?s=&threadid=21525&highlight=elbow

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