How to find PoleVector control's exact position before constrain

[highend3djojan-]

How can v find the PoleVector control's exact position in order to avoid issues like flipping later?

[joojaa]

The reason you move pole vectpr is to counter the flip. THing is theres GOING to be a flip somewhere so you better be able to move the pole to match suite.

So no its impossible to positioona pole vector so it can anver flip, uless offcourse theres some contraint to how much the joimnts can trun so it never reaches suich areas. But then you wouldt use a pole vector constraint.

[arunpillaii]

In Normal Orientation , for pole vector just snap the control to knee/Elbow and move , then add pole vector contraint. there is no movement for joints and the pole vetro will be fine. But if your joint having any rotations , some times when we apply pole vector it shows a movement or flipping . This time we need to  find where the exact position of control ? One simple way to find the Position is:

if leg/Arm joints are 'A' , 'B'  and 'C''

just create a polygon using create polygon tool by taking the position of A B and C

now we will get a plane with three vertexs

now take the pole vector control , contraint it with knee/Elbow joint with out maintain offset

delete constraint, so control will  be in exact knee/Elbow joint

now now apply a normal constraint from the above created polygon mesh to control

then the control will take a rotation

change move tool to object space. move the control to front as much as needed

delete the normal constraint

now apply pole vector constraint to that control..............it will be in correct position

[pdelappe]

Yes, this is a well-known flaw in Maya's IK systems. As I believe Arun mentions above, if all the joints in your
"chain" are co-planar then all joints will lie in the IK resolution plane (also known as the IK Reference Plane).
When you apply a polevec constraint using an object in that plane the joints will not rotate.
However, "But if your joint having any rotations", or more likely,if you have a chain consisting of more than
2 joints whose translations and rotations are NOT in the same plane, the joints WILL rotate when an upvec is
applied -- unless you place the control object precisely within the IK's resolution plane . This, of course,
is difficult to do with complex joint chains.

Arun, your method of finding the resolution plane is good. Finding the IK plane for more complex chains might
pose a problem for your method since it relies on the translations of the joints in the chain and not the IK's
resolution plane itself.

When you select an IK handle the Rotation Disc, Twist Indicator and Reference Plane Indicator become visible at the
first joint in the chain. I have always wondered if one could derive the plane from the Plane Indicator. That would
make placing pole vector controls easy.

Note that this problem did not exist for Softimage3D. If you applied an upvector control to an IK that was not in the
resolution plane the constraint was created with an offset which preserved the pose of the bones in the chain. With
XSI that functionality does not exist (as far as I know), but there is a way to see the plane in the viewport as a triangle.
You can place your constraint object very close to the apex of this triangle which will minimize the bone rotations created
when the Chain Up Vector is applied.

Anyone out there know a more precise way to place Chain UpVecs in XSI?

When you select an IK handle the Rotation Disc, Twist Indicator and Reference Plane indicator become visible at the

first joint in the chain. I have always wondered if one could derive the plane from the Plane Indicator. That would

make placing pole vecotr controls easy.

Note that this problem did not exist for Softimage3D. If you applied an upvector control to an IK that was not in the

resolution plane the constraint was created with an offset which preserved the pose of the bones in the chain. With

XSI that functionality does not exist (as far as I know), but there is a way to see the plane in the viewport as a triangle.

You can place your constraint object very close to the apex of this triangle which will minimize the bone rotations created

when the Chain Up Vector is applied.

Anyone out there know a more precise way to place Chain UpVecs in XSI?

[joojaa]

Oh deary deary me. This is not a bug its a well tought feature, a bit old tough so there are better ways nowdays).

I have always wondered if one could derive the plane from the Plane Indicator.

Yup. No problem whatsoever. Maya boracast the pole vector (even if ist not constrained) in the solver node (assuming your using a ik with a pole vector) you can calculate the plane form the broadcasted pole.