Biped IK rig flakey - parent constraints work 25% of the time

[Terrain-Lab]

I have a character rig imported from 3DSMax Biped. It has the end effectors which are opaque in the viewport, which I can't set to transparent, and can't see through to animate.  So I created curves to act as controller handles, parent-constrained the effectors to the curves, and turned off the effector visibility.  It works great - some of the time.

If I move a control object, the rig responds, but if I hit Undo, then the rig ignores any further movement of that control until I move another part of the rig.  Sometimes that will cause it to respond to the control again, but often it now has a new offset value from the control and the rig positions no longer match the control object positions.

If I key a control position, then change frames, it changes or loses the values I had just keyed.  I'm finding that the effectors are sometimes nicely obeying the constraints, and the rig simply ignores them.  In other cases, the control object is in one orientation, the effector in a totally different orientation, and the rig seems to have doubled the offset between the controller and the effector. (again, this happens only after I change frames and then come back to the edited frame)

I found that changing the "blending" values for the parent constraint to be "use input 2 only" makes the effectors quit ignoring movement of my control objects.  Now I can pose the rig nicely, keying all my controller positions.  But when I change frames and come back, the rig is all twisted up, even though most of the end effectors are right where they should be.

I've never dealt with this "blending" node before, and wonder if this is due to some higher-level controls fighting against me.  (for instance, I've never seen Reach Translation or Reach Rotation fields before this)

Any ideas??

Thanks!

[santd]

Hello,

Thank you for posting on The Area forums. I tried brining a Biped rig from 3ds Max into Maya and was not able to see the effector to see if it is possible to change the visibility of it or not. I used the send to function and it only seemed to have bring in the joints.

I'm thinking that in the long run it is going to be better to figure out a way to change the visibility than to get the contrain on the effectors to work.

Another option that I see is to do a direct parent instead of a parent constraint. The difficulty with this is that it could possibly affect the heirarchy of the effector.

If possible could you attach a Maya scene that displays the issue you are having with the effector. Then I can test this on my end.

Cheers,

[Terrain-Lab]

David, thanks for your help.

I don't know how our vendor got this from Max into Maya, but the rig uses FBIK and has a character set assigned.  

I was having trouble with the rig often not responding to the effector positions.  The Autodesk fbikguide.pdf for Maya 2012 on page 25 says that you cannot use Autokey with an FBIK rig.  It also says that in order to get the S keyboard shortcut to work for setting keys, you have to change the animation preferences. I just tried changing animation preferences for character sets to "key all attributes" and not just modified attributes.  On those frames where things are acting really funny, now going back and re-keying them seems to fix the issues.  

I was initially using geometry as controllers, with the effectors parent-constrained to that geometry, and having lots of trouble.  Then I read an Autodesk article saying that using constraints on FBIK effectors will break the rig.

Since I'm using 2014, I wondered if that issue still exists.  I'm finding that keying just one effector doesn't produce good results.  The entire dependency set has to be keyed for FBIK to work.  So as a result, using controller objects with constraints to drive the effectors won't work, because keying the controller object won't key all the dependencies in the FBIK rig.  So in short, the answer is that I can't use controller objects with FBIK.  I'll have to look into HumanIK when I can.

So I think I've gotten the intermittent response issue resolved.  Regarding the display of the effectors, I can change their displayed size and shape, but I can't find a way to make them display as wireframes or outlines.  If I could change them to have outlined display, I could see better to animate - but that's not as big a deal.

As is, I'm up and running, and the rig is now animating properly.

[santd]

Hello,

I appreciate the information and glad to hear you are up and running. The issue with contraining objects to effectors still stands. I have had times when an object such as a weapon would need to be parented to a writst effector so that it would stick when animating the hand. However, it is best to contrain it to the wrist joint as constraining to an effector will cause issues.

I may be confused on this part, but in Maya FBIK is HumanIK and in the attributes for it there are different option for keying. You can animate full parts like the entire arm or just controls hand elbow shoulder or the entire body. Working in different modes can cause issues because working in parts will key all controls on the arm; however in control mode it will only key the selected control.

In regards to the display of the effectors. I noticed the effectors I create have a "Look" option which allows you to multiple different options. Maybe one of the other options will make it easier for you to animate.

Cheers,