CGTalk - Weird bone rotation on elbow bend

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brentlowrie

01-08-2002, 11:52 AM

Hi All

I have a weird rotation thing happening with a number of my rigs. It has occurred in at least three different rigs, all created differently.

One arm will be fine but the other is not. As I animated the arm bending, elbow straight back, hand moving laterally toward shoulder (to test skin mod). As the arm animates, the upper arm and lower arm bones rotate in an odd way, the elbow first moving upp, then down then up again. The mesh twists as the arm moves. Again only in one arm.

I have been playing with the preferred angles in the Rotational Joint rollout but to no avail. Please help!:confused:

Iain McFadzen

01-08-2002, 08:28 PM

Which Max are you using? IK in Max3 and Max4 are completely different, so the right answer will depend on which one you are using.

Assuming you are using Max4 with HI solver (if you are using Max4 you chould be)...

Sounds like you aren't dealing with your swivel angles. If you select the IK chain (the lil' blue cross) and go into the motion panel you will find a control for swivel angle. This controls the rotation of the limb along the exis of the solver. You can use (and if necessary animate) the spinner value if you like, or you can create a dummy object and use it as a target.

Assuming you are using Max3...

You will need to adjust your joint limits, specifically for the shoulder joint. I can't be any more specific cos it's a long time since I used Max3.

brentlowrie

01-09-2002, 12:43 PM

Thanks for the reply.

I am using 4.26 and HI Solvers and have targets for the elbows. I have actually played with the swivel in the Motion panel and have achieved and acceptible result between all the tweaks. Just a lot of work to bring it to that point. I don't know why the one arm would wig out when the other was fine prior to my muckin' about.

Perhaps its my scale. I am using feet and inches as units and my characters are all between 4 and 6 feet tall. This seems small compared to other models I have downloaded from the web. How do you approach scale?

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