SimplyMaya Forums

Welcome to the forum, feel free to ask questions here.

Home / forum / Animation / Animation / Getting IK to work in reverse...
Register FAQ Members List Calendar Mark Forums Read

New Thread
 
Thread Tools
Old 25-11-2002, 04:23 AM   #1
dkouts
Registered User
 
dkouts's Avatar
 
Join Date: Oct 2002
Location: Australia
Posts: 46
Thanks: 0
Thanked 0 Times in 0 Posts
Question Getting IK to work in reverse...

Consider a simple leg joint chain :

*Hip

*Knee

+Ankle

OK, you can grab the ankle IK handle and drag the leg into a pose,
but suppose you wanted to grab the characters hips and push him
down (as if preparing to jump) how do you make the ankles hold
their position, on the 'floor' and have the knees bend logically as
when moving the ankle IK handle up?

Effectively animating with IK, but from the top down?
Whenever Ive laid down a quick IK chain in Houdini, I was always
able to just grab the 'top' of the IK chain and have it work as I described.

But maybe theres an extra step in Maya that Im missing?

Dan
dkouts is offline   Reply With Quote
Old 25-11-2002, 05:03 AM   #2
mtmckinley
The Maya Mountain
 
mtmckinley's Avatar
 
Join Date: Aug 2002
Location: Seattle, WA
Posts: 8,245
Thanks: 1
Thanked 25 Times in 25 Posts
Default

It works for me, but it might be because of the way I create a foot structure for animation purposes. I've attached an image of what I do in this thread:

http://forum.simplymaya.com/showthre...?threadid=2034
__________________
-Mike
www.mtmckinley.net
The Maya Toolbelt
mtmckinley is offline   Reply With Quote
Old 25-11-2002, 06:11 AM   #3
dkouts
Registered User
 
dkouts's Avatar
 
Join Date: Oct 2002
Location: Australia
Posts: 46
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Thanks for the reply, Mike. nice image!

So taking my simple rig as an example -

hip,
knee,
ankle,
connect with IK handle...

would you EXPECT the hips to be able to drive the knee rotation
with no more parenting / IK tooling than that?

Are you able to replicate that effect just quickly in a side view, for example?

Dan
dkouts is offline   Reply With Quote
Old 25-11-2002, 02:49 PM   #4
Kurt
Registered User
 
Kurt's Avatar
 
Join Date: May 2002
Location: Niagara Falls, Canada
Posts: 5,298
Thanks: 0
Thanked 64 Times in 64 Posts
Default

dkouts, Mike builds a great skelly!!! his setup is pretty much the same as I do.

Skeletons can be a pain in the butt, the nodes are set up and parented diffrent ways depending on what your little guy will be performing.

Most of the time just selecting the root joint, is all you need to get the character to bend at the knee's (like getting ready for a jump) while the foot stays planted.

What node are you selecting in the hypergraph? Did you put your IK nodes into the same chain as the rest of the skelly?

If you did that might be the problem right there, most of the time if the character is just going to be runing and walking about, the ik nodes can stay out, If you want to jump and tumble you have to make a new node buy grouping the Root joint to itself, then parenting the IK's to the new node you made.

It sounds like the node your picking in your chain might have been grouped with the root and ik's together which will select the whole skeleton together making a node that highlites all the joints and moves all the joints at once.

If you do have the iks parented to your root joint try unparenting them. Once you have done that select your root joint again and group it to itself, call it (Flip) or something along that line and add the iks to that node. Now if that was what the problem was select the root joint only, you should be able to get the up/down action your looking for while the feet stay planted. Then if you select the new node you made called flip that should select the whole skelly and you should be able to flip him if you wanted him to jump head over heels.

Its a bit hard to say what the problem is with out seeing the way you set-up the skelly=)

Hope that helps, they can be tricky


Kurt
__________________
I am enough of an artist to draw freely upon my imagination, knowledge is limited, imagination encircles the world. (Albert Einstein)

http://kurtboutilier.cgsociety.org/

Last edited by Kurt : 25-11-2002 at 03:04 PM.
Kurt is offline   Reply With Quote
Old 25-11-2002, 11:04 PM   #5
dkouts
Registered User
 
dkouts's Avatar
 
Join Date: Oct 2002
Location: Australia
Posts: 46
Thanks: 0
Thanked 0 Times in 0 Posts
Thumbs up Thats got it!

Kurt, you are my new best friend!
I was grabbing the root joint in the outliner, but there was no group node parenting it. I have gotten it to work thanks to your description.

And Mike, thanks for your reply too.

I will be telling every Maya user who asks me about web resources to check out Simply Maya - I get more results from the guys in this community than the Alias Wavefront Official E-Support website.

Hope I can contribute more when I get more experienced.

And Mike, Ive checked out your tutorial site too - very helpful as well.

Dan:banana:
dkouts is offline   Reply With Quote
Old 25-11-2002, 11:12 PM   #6
Kurt
Registered User
 
Kurt's Avatar
 
Join Date: May 2002
Location: Niagara Falls, Canada
Posts: 5,298
Thanks: 0
Thanked 64 Times in 64 Posts
Default

Glad I can help bud=)
__________________
I am enough of an artist to draw freely upon my imagination, knowledge is limited, imagination encircles the world. (Albert Einstein)

http://kurtboutilier.cgsociety.org/
Kurt is offline   Reply With Quote
Old 25-11-2002, 11:21 PM   #7
mtmckinley
The Maya Mountain
 
mtmckinley's Avatar
 
Join Date: Aug 2002
Location: Seattle, WA
Posts: 8,245
Thanks: 1
Thanked 25 Times in 25 Posts
Default

glad to help.
__________________
-Mike
www.mtmckinley.net
The Maya Toolbelt
mtmckinley is offline   Reply With Quote
Old 30-11-2002, 05:28 PM   #8
DukerX
Subscriber
 
DukerX's Avatar
 
Join Date: Nov 2002
Location: Sandnes, Norway
Posts: 99
Thanks: 0
Thanked 0 Times in 0 Posts
Default "Sticky" IK handle

You could also make the IK handle "sticky" in the properties editor.
That would make the IK handle stay in place when you move the hip around, and animate the legs according to the movement if the hip.
__________________
-DX-
DukerX is offline   Reply With Quote
Old 02-12-2002, 01:51 PM   #9
dkouts
Registered User
 
dkouts's Avatar
 
Join Date: Oct 2002
Location: Australia
Posts: 46
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Thanks Duker. Is 'sticky' a Maya tool, or are you using that word just to imply locking the feet down?

: - )

Dan
dkouts is offline   Reply With Quote
Old 02-12-2002, 03:38 PM   #10
kbrown
Moderator
 
kbrown's Avatar
 
Join Date: Sep 2002
Location: London, UK
Posts: 3,198
Thanks: 0
Thanked 8 Times in 8 Posts
Default

If you key the feet translations and then move the root joint, the feet will stay locked down.
__________________
Kari
- My Website
- My IMDB

Do a lot, Fail a lot and Learn a lot!
kbrown is offline   Reply With Quote
New Thread

« Previous Thread | Next Thread »

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Thumbnails in WIP & Finished Work Miss_Nova Site News & Announcements 11 09-12-2010 05:22 AM
Character animation-Finished work maheshsubbiah Finished Work 7 05-12-2010 04:04 AM
Saw II work mtmckinley Finished Work 8 16-11-2010 12:33 PM

1 Month

$34

Month-to-month billing
$34/month
Unlimited access to all videos
Project files to download
Easy to cancel at anytime
 
 

3 months

$87

Billing every 3 months
$29/month
Unlimited access to all videos
Project files to download
Easy to cancel at anytime
Save $5 per month or $15 in total compared to monthly billing with this package.

12 months

$288

Billing every 12 months
$24/month
Unlimited access to all videos
Project files to download
Easy to cancel at anytime
Save $10 per month or $120 in total compared to monthly billing with this package.

Your plan will automatically renew. You can cancel at any time via your PayPal account to avoid being charged again.

You can view the FAQ on our video plans here. You can contact us directly here. By clicking one of the buttons above, you agree to our Terms and Privacy Policy.