Beer glass scene creation
This course contains a little bit of everything with modeling, UVing, texturing and dynamics in Maya, as well as compositing multilayered EXR's in Photoshop.
# 1 21-04-2011 , 04:16 PM
elephantinc's Avatar
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Weird IK

I'm trying to animate a stick figure typing and Im using IK to animate the arms. It works fine for one arm but the other is doing some weird things in between keys (see video). Any idea what the cause is?

YouTube - Weird IK

# 2 21-04-2011 , 04:38 PM
LauriePriest's Avatar
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Looks like joint flipping, your joint orientations must be wrong, are you mirroring the joints, what settings are you using if you are?

Also how are you creating the joints. Do you just create them in side view and then use the insert key to adjust the position? if this is the case its likey you will get incorrect joint orientations, there are a few scripts out there that handle joint orientations for you while allowing you to easily modify joint positions/ Otherwise the safest way to edit your joints is to adjust the local translate x only to define the length of a bone and then use the joint orientations attributes in the attribute editor to change the orientation. Using the insert key to move joints just changes the translate position but doesnt update the orientations.

Its probably best to use the behaviour function of the mirror joints tool as it will keep the x axis along the joint, if you use the orientation function it will not keep the axis in line with the joints at all, it keeps the orientations as they where and just moves the joints.

Also use a polve vector constraint if you aren't already to keep the transforms in check .


FX supervisor - double negative
# 3 21-04-2011 , 05:25 PM
elephantinc's Avatar
Level 32 pachyderm
Join Date: Dec 2007
Location: England
Posts: 1,859

Looks like joint flipping, your joint orientations must be wrong, are you mirroring the joints, what settings are you using if you are?

Also how are you creating the joints. Do you just create them in side view and then use the insert key to adjust the position? if this is the case its likey you will get incorrect joint orientations, there are a few scripts out there that handle joint orientations for you while allowing you to easily modify joint positions/ Otherwise the safest way to edit your joints is to adjust the local translate x only to define the length of a bone and then use the joint orientations attributes in the attribute editor to change the orientation. Using the insert key to move joints just changes the translate position but doesnt update the orientations.

Its probably best to use the behaviour function of the mirror joints tool as it will keep the x axis along the joint, if you use the orientation function it will not keep the axis in line with the joints at all, it keeps the orientations as they where and just moves the joints.

Also use a polve vector constraint if you aren't already to keep the transforms in check .

I used behaviour to mirror them and I create the joints in the front view, the model was fairly two dimensional so I didn't have to move them.

Thanks for the help, I'll take a look at the orientations.

# 4 23-04-2011 , 09:16 PM
elephantinc's Avatar
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Join Date: Dec 2007
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Posts: 1,859
Worked a treat, thanks again. user added image

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