Lets create a simple knee setup. We are going to add the knee pole vector but also create a line from the knee to the knee anim.
This will help the animator know which knee anim goes to which knee. This is simple, and very helpful to the animator.
STEP 1: Create a curve
We are going to create a line from the knee to the anim. Lets start by creating a straight line..
Use the EP Curve tool, create -> EP curve tool. Make sure the curve degree is 1(linear) in the tool box.
This will create a linear curve. Just put the two points anywhere.
Rename the curve "left_knee_pointer_curve".
STEP 2: Create the clusters
Now we are going to create a cluster.
Clusters are useful, they are designed for easy selection of CV's and vertices.
They also make animating CV's vertices very easy.
Actually binding skin is a type of cluster.
In CV mode, select one of the CV's, go to animate menu set -> create deformer-> cluster.
Name the cluster "left_knee_pointer_start".
Create another cluster on the other side, name it "left_knee_pointer_end".
STEP 3: Constrain the Clusters
Now we will position the clusters.
Select the lowerLeg ik joint and then the start cluster.
Create a point constraint, constraint -> point -> options.
Make sure maintain offset is off.
Select the knee anim then the end cluster.
Then create another point constrain (g).
Now there should be a line from your knee to your anim.
STEP 4: Finish up the knee and foot details
Select the knee curve. Now if you template the curve the animator can't accidently select it.
Display -> object display -> template.
Group the clusters and the knee pointer curve together.
Rename the group, "left_knee_pointer_grp".
Group the pointer grp, the foot anim, and the knee anim together, rename the group, "left_leg_anim_grp".
Place the left_leg_anim_grp, under the anims_grp.
Last but not least create the poleVector constraint.
Select the knee anim then the left_leg_ik and create a pole vector constraint.
Hide the clusters, and the left_heel_piv.
STEP 4: Fix attrs
Select the foot anim.
Lock and hide the scales and visibility.
Select the attrs -> right click -> lock and hide selected.
Lock and hide the rotates, scales and visibility of the knee_anim.